血管內膜的進行性增厚是動脈粥樣硬化的重要標誌，並最終導致閉塞性血管病。血管內膜增生的一個主要因素是血管中膜的平滑肌細胞遷移至內膜層並增殖。大量研究證實，在動脈粥樣硬化的發生發展中，過量產生的活性氧簇（ROS）參與了血管壁的增厚。M型瞬時受體電位通道亞家族的成員TRPM2在血管平滑肌細胞中有表達，它能被ROS激活並對Ca²⁺通透，但其在血管平滑肌中的功能以及與心血管疾病的聯繫尚未見報道。 / 本論文著眼於探討TRPM2在鼠和人血管內膜增生中的作用。用血管外周套管法建立在體齧齒類動脈內膜增生模型。套管放置2周後，大鼠股動脈可見明顯的內膜增厚。免疫染色顯示新生內膜及其鄰近中膜區域內有大量增殖細胞核抗原陽性細胞，提示在增生的動脈中，細胞週期活動增強。動脈內膜和中膜内二氫乙錠螢光信號顯著增強，提示了ROS的過量生成。免疫染色和免疫印跡法均顯示，套管損傷導致TRPM2表達上調。免疫螢光雙標TRPM2與α-平滑肌肌動蛋白顯示內膜區域有大量TRPM2陽性的平滑肌細胞。與正常股動脈中膜平滑肌細胞相比，次黃嘌呤和黃嘌呤氧化酶在套管損傷的動脈來源的新生內膜平滑肌細胞中引起更大幅度的細胞內鈣離子濃度升高，而TRPM2抑制性抗體TM2E3預處理可消除這種差異。套管放置3周可引起小鼠頸動脈新生內膜形成，並伴隨著TRPM2表達上調。敲除TRPM2基因可顯著抑制內膜增生。取冠狀動脈搭橋術後殘餘的大隱靜脈，離體培養2周誘導內膜增生。免疫螢光雙標TRPM2與α-平滑肌肌動蛋白顯示新生內膜內含有大量TRPM2陽性的平滑肌細胞。TM2E3和另一TRPM2抑制劑2-氨乙氧基二苯酯硼酸處理均可有效降低內膜的增生。培養齧齒類主動脈平滑肌細胞，用劃痕試驗和MTT法檢測TRPM2阻斷劑和TRPM2基因敲除對過氧化氫誘導的細胞遷移和增殖的影響。結果顯示，暴露於過氧化氫48小時，細胞的遷移和增殖均明顯加快。TM2E3和2-氨乙氧基二苯酯硼酸處理有效抑制過氧化氫誘導的大鼠主動脈平滑肌細胞遷移和增殖；類似地，TRPM2基因敲除可顯著抑制過氧化氫誘導的小鼠主動脈平滑肌細胞遷移和增殖。 / 以上結果表明，血管內膜增生伴隨著TRPM2表達的上調；TRPM2參與了血管內膜增生以及血管平滑肌細胞的遷移、增殖；抑制TRPM2可能是對抗血管內膜增厚的潛在治療手段。 / A hallmark in atherosclerosis is progressive intimal thickening, which leads to occlusive vascular diseases. A causation of neointimal hyperplasia is the migration of medial smooth muscle cells (SMCs) to the intima where they proliferate. It is well recognized that excessive production of reactive oxide species (ROS) contributes to vascular wall thickening during arteriosclerotic development. TRPM2, a member of the melastatin-like transient receptor potential channel subfamily, is a Ca²⁺-permeable cation channel activated by ROS and is expressed in vascular smooth muscle cells (VSMCs). The functional properties of TRPM2 in vascular smooth muscle remain to be identified and an association between TRPM2 and cardiovascular diseases has not been reported. / In the present study, I investigated the involvement of TRPM2 in rodent and human neointimal hyperplasia. In vivo neointimal hyperplasia in rodent arteries was induced by perivascular cuff placement. After the cuff placement for 2 weeks, rat femoral arteries showed distinct intimal thickening. Immunostaining showed a great number of PCNA-positive proliferating cells in the neointima and its adjacent media region, indicating the enhanced cell cycle activity in the hyperplasic arteries. Dihydroethidium signal was markedly increased in the neointima and media of the cuffed arteries, suggesting that ROS is over-produced. Interestingly, both immunostaining and immunoblot showed that cuff-injury also led to an up-regulated expression of TRPM2. Double immunofluorescent labeling of TRPM2 and α-smooth muscle actin showed a large amount of TRPM2-positive SMCs in the neointimal region. Compared with the normal medial SMCs isolated from non-cuffed arteries, the neointimal SMCs from cuff-injured arteries displayed a greater [Ca²⁺] rise in response to hypoxanthine-xanthine oxidase, which was inhibited by pre-treatment with a TRPM2-specific blocking antibody TM2E3. In mouse carotid arteries, cuff placement for 3 weeks caused clear neointimal formation, accompanied by up-regulated expression of TRPM2. Trpm2 disruption dramatically reduced the neointimal growth. Human saphenous vein samples obtained during CABG surgery were organ-cultured for 2 weeks to allow growth of neointima. Double immunofluorescent labeling of TRPM2 and α-smooth muscle actin showed that the neointima contained numerous TRPM2-positive SMCs. Neointimal hyperplasia in the veins was effectively suppressed by in vitro treatment with TM2E3 or a chemical blocker 2-aminoethoxydiphenyl borate. Furthermore, the effect of TRPM2 blockers and Trpm2 disruption on hydrogen peroxide-induced migration and proliferation of cultured rodent aortic SMCs were evaluated by scratch wound healing assay and MTT assay, respectively. It was found that exposure to hydrogen peroxide for 48 hour substantially enhanced the migration and proliferation of rodent aortic SMCs. In rat aortic SMCs, both TM2E3 and 2-aminoethoxydiphenyl borate significantly inhibited the hydrogen peroxide-induced cell migration and proliferation. The hydrogen peroxide-induced cell migration and proliferation of SMCs was also reduced in Trpm2 knockout mice. / Taking together, these results provide strong evidences that in vivo neointimal hyperplasia is accompanied by an up-regulated expression of TRPM2 and that TRPM2 plays a key role in neointimal hyperplasia, VSMCs migration and proliferation. Blocking TRPM2 can be a potential therapeutic approach for protecting blood vessels against intimal thickening. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Ru, Xiaochen. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 125-151). / Abstracts also in Chinese. / Declaration of Originality --- p.i / Abstract --- p.ii / 論文摘要 --- p.iv / Acknowledgements --- p.vi / Abbreviations and Units --- p.vii / Table of Content --- p.x / List of Figures --- p.xvi / List of Tables --- p.xviii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Neointimal hyperplasia --- p.1 / Chapter 1.1.1 --- Definition of neointimal hyperplasia --- p.2 / Chapter 1.1.2 --- Medical significance of coronary neointimal hyperplasia --- p.3 / Chapter 1.1.3 --- Pathogenesis of neointimal hyperplasia --- p.5 / Chapter 1.1.3.1 --- “Response to injury“ hypothesis --- p.6 / Chapter 1.1.3.2 --- Role of VSMCs --- p.7 / Chapter 1.1.3.2.1 --- VSMC phenotypic switch --- p.7 / Chapter 1.1.3.2.2 --- Ca²⁺ channel modulation in VSMCs --- p.8 / Chapter 1.1.3.2.3 --- VSMC migration --- p.9 / Chapter 1.1.3.2.4 --- VSMC proliferation --- p.10 / Chapter 1.1.3.2.5 --- Extracellular matrix production by VSMCs --- p.11 / Chapter 1.1.3.3 --- Endothelial dysfunction --- p.11 / Chapter 1.1.3.4 --- Platelet adhesion --- p.12 / Chapter 1.1.3.5 --- Inflammation --- p.13 / Chapter 1.1.4 --- Role of ROS in neointimal hyperplasia --- p.14 / Chapter 1.1.4.1 --- Types of ROS --- p.15 / Chapter 1.1.4.1.1 --- Superoxide anion --- p.16 / Chapter 1.1.4.1.2 --- Hydroxyl radical --- p.16 / Chapter 1.1.4.1.3 --- Hydrogen peroxide --- p.16 / Chapter 1.1.4.1.4 --- Nitric oxide --- p.17 / Chapter 1.1.4.2 --- Sources of ROS in vessel wall --- p.17 / Chapter 1.1.4.3 --- ROS signaling in endothelial cells --- p.19 / Chapter 1.1.4.4 --- ROS signaling in VSMCs --- p.20 / Chapter 1.1.4.5 --- ROS and atherosclerosis --- p.21 / Chapter 1.1.5 --- Current therapeutic approaches to neointimal hyperplasia --- p.23 / Chapter 1.1.5.1 --- Pharmacological approaches --- p.23 / Chapter 1.1.5.2 --- Technical Approaches --- p.25 / Chapter 1.2 --- Transient receptor potential melastatin 2 (TRPM2) channel --- p.27 / Chapter 1.2.1 --- TRP Channels --- p.27 / Chapter 1.2.2 --- TRPM2 structure and expression --- p.29 / Chapter 1.2.2.1 --- Structure --- p.29 / Chapter 1.2.2.2 --- Alternative splicing isoforms --- p.30 / Chapter 1.2.2.3 --- Expression pattern --- p.32 / Chapter 1.2.3 --- TRPM2 channel properties --- p.32 / Chapter 1.2.4 --- TRPM2 activators and inhibitors --- p.32 / Chapter 1.2.4.1 --- Activators --- p.33 / Chapter 1.2.4.1.1 --- ADPR --- p.33 / Chapter 1.2.4.1.2 --- NAD, cADPR and NAADP --- p.33 / Chapter 1.2.4.1.3 --- H₂O₂ and oxidative stress --- p.34 / Chapter 1.2.4.1.4 --- Ca²⁺ --- p.34 / Chapter 1.2.4.1.5 --- Other regulators --- p.35 / Chapter 1.2.4.2 --- Inhibitors --- p.35 / Chapter 1.2.5 --- Biological relevance of TRPM2 --- p.36 / Chapter 1.2.5.1 --- TRPM2 in insulin release --- p.36 / Chapter 1.2.5.2 --- TRPM2 in inflammation --- p.36 / Chapter 1.2.5.3 --- TRPM2 in cell death --- p.37 / Chapter 1.2.5.4 --- TRPM2-mediated lysosomal Ca²⁺ release --- p.38 / Chapter 1.2.5.5 --- TRPM2 and cardiovascular diseases --- p.39 / Chapter Chapter 2 --- Objectives of the Present Study --- p.40 / Chapter Chapter 3 --- Materials and Methods --- p.42 / Chapter 3.1 --- Materials --- p.42 / Chapter 3.1.1 --- Chemicals --- p.42 / Chapter 3.1.2 --- Media, supplements and other reagents for cell/tissue culture --- p.44 / Chapter 3.1.3 --- Antibodies --- p.45 / Chapter 3.1.4 --- Solutions --- p.46 / Chapter 3.1.4.1 --- Solutions for immunohistochemical and immunocytochemical staining --- p.46 / Chapter 3.1.4.2 --- solutions for immunoblotting --- p.47 / Chapter 3.1.4.3 --- Solutions for Genotyping --- p.49 / Chapter 3.1.4.4 --- Solutions for hematoxylin and eosin (HE) staining --- p.50 / Chapter 3.1.4.5 --- Solutions for [Ca²⁺]i measurement --- p.51 / Chapter 3.1.4.6 --- Solutions for IgG purification --- p.51 / Chapter 3.1.5 --- Animals --- p.51 / Chapter 3.1.5.1 --- Rat --- p.51 / Chapter 3.1.5.2 --- Trpm2 knockout mice --- p.52 / Chapter 3.1.5.3 --- Rabbit --- p.52 / Chapter 3.1.5.4 --- Ethics --- p.52 / Chapter 3.1.6 --- Human Tissue --- p.52 / Chapter 3.2 --- Methods --- p.54 / Chapter 3.2.1 --- Rodent models of neointimal hyperplasia --- p.54 / Chapter 3.2.1.1 --- Cuff-induced vascular injury in rat femoral artery --- p.54 / Chapter 3.2.1.2 --- Cuff-induced vascular injury in mouse carotid artery --- p.54 / Chapter 3.2.2 --- Genotyping for Trpm2 knockout mice --- p.55 / Chapter 3.2.2.1 --- Genomic DNA extraction from tail --- p.55 / Chapter 3.2.2.2 --- Polymerase Chain Reaction (PCR) --- p.55 / Chapter 3.2.2.3 --- Agarose gel electrophoresis of DNA --- p.56 / Chapter 3.2.3 --- Human saphenous vein culture and treatment --- p.56 / Chapter 3.2.4 --- Generation of anti-TRPM2 antibody, TRPM2-specific blocking antibody TM2E3 and preimmune IgG --- p.57 / Chapter 3.2.5 --- Histological analysis and immunohistochemistry --- p.58 / Chapter 3.2.6 --- Western blotting --- p.59 / Chapter 3.2.7 --- Detection of ROS production by dihydroethidium fluorescence --- p.60 / Chapter 3.2.8 --- Isolation of rodent neointimal and medial smooth muscle cells --- p.60 / Chapter 3.2.9 --- Culture of rodent aortic smooth muscle cells --- p.61 / Chapter 3.2.9.1 --- Cell culture --- p.61 / Chapter 3.2.9.2 --- Cell identification --- p.61 / Chapter 3.2.10 --- [Ca²⁺]i measurement --- p.62 / Chapter 3.2.11 --- Cell proliferation assay --- p.63 / Chapter 3.2.12 --- Cell migration assay --- p.63 / Chapter 3.2.13 --- Statistical analysis --- p.64 / Chapter Chapter 4 --- ROS over-production and TRPM2 up-regulation in cuff-induced rodent neointimal hyperplasia --- p.65 / Chapter 4.1 --- Introduction --- p.65 / Chapter 4.2 --- Materials and Methods --- p.66 / Chapter 4.2.1 --- Cuff-induced vascular injury in rat femoral artery --- p.66 / Chapter 4.2.2 --- Preparation of anti-TRPM2 antibody, TM2E3 and preimmune IgG --- p.66 / Chapter 4.2.3 --- Histological analysis and immunohistochemistry --- p.66 / Chapter 4.2.4 --- Western blotting --- p.67 / Chapter 4.2.5 --- Detection of ROS production --- p.67 / Chapter 4.2.6 --- Isolation of rat neointimal and medial smooth muscle cells --- p.68 / Chapter 4.2.7 --- [Ca²⁺]i measurement --- p.68 / Chapter 4.2.8 --- Statistical analysis --- p.68 / Chapter 4.3 --- Results --- p.69 / Chapter 4.3.1 --- Cuff-induced neointimal hyperplasia in rat femoral arteries --- p.69 / Chapter 4.3.2 --- ROS over-production in neointimal region of cuff-injured rat femoral arteries --- p.69 / Chapter 4.3.3 --- TRPM2 up-regulation in neointimal region of cuff-injured rat femoral arteries --- p.69 / Chapter 4.3.4 --- Enhanced [Ca²⁺]i response to HX-XO in rat neointimal smooth muscle cells --- p.70 / Chapter 4.4 --- Discussion --- p.81 / Chapter Chapter 5 --- TRPM2 contributes to human and rodent neointimal hyperplasia --- p.86 / Chapter 5.1 --- Introduction --- p.86 / Chapter 5.2 --- Materials and Methods --- p.87 / Chapter 5.2.1 --- Cuff-induced vascular injury in mouse carotid artery --- p.87 / Chapter 5.2.2 --- Genotyping for Trpm2 knockout mice --- p.87 / Chapter 5.2.3 --- Organ culture of human saphenous vein --- p.87 / Chapter 5.2.4 --- Preparation of anti-TRPM2 antibody, TM2E3 and preimmune IgG --- p.88 / Chapter 5.2.5 --- Histological analysis and immunohistochemistry --- p.88 / Chapter 5.2.6 --- Western blotting --- p.88 / Chapter 5.2.7 --- Isolation of mouse neointimal and medial smooth muscle cells --- p.89 / Chapter 5.2.8 --- [Ca²⁺]i measurement --- p.89 / Chapter 5.2.9 --- Statistical analysis --- p.90 / Chapter 5.3 --- Results --- p.90 / Chapter 5.3.1 --- Cuff-induced neointimal hyperplasia was reduced in Trpm2 knockout mice --- p.90 / Chapter 5.3.2 --- [Ca²⁺]i response to HX-XO in mouse neointimal smooth muscle cells --- p.90 / Chapter 5.3.3 --- Inhibiting TRPM2 reduced the neointimal hyperplasia in in vitro cultured human saphenous vein --- p.91 / Chapter 5.4 --- Discussion --- p.99 / Chapter Chapter 6 --- Role of TRPM2 in H₂O₂-stimulated migration and proliferation of vascular smooth muscle cells --- p.103 / Chapter 6.1 --- Introduction --- p.103 / Chapter 6.2 --- Materials and Methods --- p.104 / Chapter 6.2.1 --- Culture of rodent aortic smooth muscle cells --- p.104 / Chapter 6.2.2 --- Immunocytochemistry --- p.104 / Chapter 6.2.3 --- Genotyping for Trpm2 knockout mice --- p.104 / Chapter 6.2.4 --- Preparation of anti-TRPM2 antibody, TM2E3 and preimmune IgG --- p.104 / Chapter 6.2.5 --- [Ca²⁺]i measurement --- p.105 / Chapter 6.2.6 --- Cell proliferation assay --- p.105 / Chapter 6.2.7 --- Western blotting --- p.105 / Chapter 6.2.8 --- Cell migration assay --- p.106 / Chapter 6.2.9 --- Statistical analysis --- p.106 / Chapter 6.3 --- Results --- p.106 / Chapter 6.3.1 --- H₂O₂-induced [Ca²⁺]i rises in rodent aortic smooth muscle cells --- p.106 / Chapter 6.3.2 --- Role of TRPM2 in H₂O₂-stimulated smooth muscle cell proliferation --- p.107 / Chapter 6.3.3 --- Role of TRPM2 in H₂O₂-stimulated smooth muscle cell migration --- p.108 / Chapter 6.4 --- Discussion --- p.118 / Chapter Chapter 7 --- General Conclusion and Future Work --- p.121 / Chapter 7.1 --- Concluding remarks --- p.121 / Chapter 7.2 --- Future work --- p.123 / Chapter 7.2.1 --- Specific downstream signaling pathway of TRPM2 that mediates ROS-induced VSMC proliferation and migration --- p.123 / Chapter 7.2.2 --- Involvement of TRPM2 in leukocyte infiltration and inflammation in vascular wall --- p.124 / References --- p.125 / List of Publications --- p.152

壓力感受器在調節血壓的壓力感受性反射中的作用已是眾所周知。兩個動脈壓力感受器，分別為主動脈壓力感受器和頸動脈壓力感受器。它們作為重要的感應器以檢測主要動脈血壓，並和孤束核溝通，從而調節血壓。然而，壓力感受器的機械力敏感元件的分子身份仍是奧秘。因為機械敏感的陽離子通道受機械力刺激時會增加的神經元活動, 所以機械敏感的陽離子通道是合適的候選人。 / 在本研究中，通過使用膜片鉗和動作電位的測量，瞬时受体电位通道C5(TRPC5)被確定在主動脈壓力感受器的機械傳感器中。透過在壓力感受器神經元的鈣測量實驗，證實TRPC5參與由拉伸引起的鈣離子([Ca²⁺]i)上升。TRPC5基因敲除小鼠出現壓力感受器功能受損, 表明了TRPC5在血壓控制的重要性。 / 比較主動脈壓力感受器或頸動脈壓力感受器的不同敏感度現時存有不少爭論。在本研究中，我發現主動脈壓力感受器比頸動脈壓力感受器對於壓力變化更加敏感。此外，我還發現了主動脈壓力感受器神經元比頸動脈壓力感受器神經元有一個相對較高的瞬时受体电位通道V4(TRPV4)表達。鈣測量研究表明TRPV4通道在主動脈壓力感受器神經元的靈敏度可能發揮著重要作用。 / Baroreceptors have been well known for its role in the baroreflex regulation of blood pressure. Two arterial baroreceptors, aortic and carotid baroreceptors, serve as the important sensors to detect blood pressure in main arteries, and they communicate with the solitary nucleus tract for blood pressure regulation. However, the molecular identity of the mechano-sensitive components in the baroreceptors is still mysteries. Mechano-sensitive cation channels are the fascinating candidates as they increase neuronal activities when stimulated by stretch. In the present study, with the use of patch clamp and action potential measurement, TRPC5 channels were identified to be the mechanical sensor in the aortic baroreceptor. Calcium measurement studies demonstrated that TRPC5 was involved in the stretch-induced [Ca2+]i rise in baroreceptor neurons. The importance of TRPC5 in blood pressure control was also studied in TRPC5 knockout mice, which displayed an impaired baroreceptor function. / There have been controversies as to whether aortic baroreceptors or carotid baroreceptors are more sensitive to the change in blood pressure. In the present study, aortic baroreceptor was found to be more sensitive to the pressure change than the carotid baroreceptor. Furthermore, I also found a relative higher expression of TRPV4, a mechanosensitive channel, in the aortic baroreceptor neurons than in the carotid baroreceptor neurons. Moreover, calcium measurement studies showed that TRPV4 channels should play an important role in governing the differential pressure sensitivity in these two types of baroreceptor neurons. / Taken together, the present study provided novel information on the role of TRPC5 and TRPV4 in baroreceptor mechanosensing. In future, it will be of interest to explore whether TRPC5 and/or TRPV4 dysfunction could contribute to human diseases that are related to blood pressure control. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lau, On Chai Eva. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 133-152). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Declaration --- p.i / Abstract of the thesis entitled --- p.ii / Acknowledgement --- p.vii / Abbreviation --- p.ix / Table of content --- p.xii / List of figures --- p.xv / List of table --- p.xvii / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Baroreceptors --- p.1 / Chapter 1.1.2 --- Arterial baroreceptors --- p.2 / Chapter 1.1.2.1 --- Functions of arterial baroreceptors --- p.4 / Chapter 1.1.2.2 --- Sensitivity of the arterial baroreceptors --- p.6 / Chapter 1.1.3 --- Other baroreceptors --- p.8 / Chapter 1.1.4 --- The molecular identity of the mechanosensors in baroreceptor neurons --- p.9 / Chapter 1.2 --- Transient receptor potential ion channels (TRP channels) --- p.10 / Chapter 1.2.1 --- TRP channels superfamily --- p.10 / Chapter 1.2.2 --- Multimerization of TRP channels --- p.12 / Chapter 1.2.3 --- Physiological functions --- p.14 / Chapter 1.2.4 --- Mechanosensitive TRP channels --- p.16 / Chapter 1.2.5 --- Canonical transient receptor potential 5 (TRPC5) channels --- p.17 / Chapter 1.2.6 --- Vanilloid transient receptor potential 4 (TRPV4) channels Figures --- p.20 / Chapter Chapter 2: --- Objectives --- p.34 / Chapter Chapter 3: --- Materials and Methods --- p.35 / Chapter 3.1 --- Materials --- p.35 / Chapter 3.1.1 --- Chemicals and reagents --- p.35 / Chapter 3.1.2 --- Solutions --- p.36 / Chapter 3.1.2.1 --- Solutions for calcium imaging --- p.36 / Chapter 3.1.2.2 --- Solutions for electrophysiology study --- p.38 / Chapter 3.1.2.3 --- Solutions for agarose gel electrophoresis --- p.41 / Chapter 3.1.3 --- Primers for RT-PCR --- p.42 / Chapter 3.1.4 --- Animals --- p.43 / Chapter 3.2 --- Methods --- p.43 / Chapter 3.2.1 --- Total RNA isolation and RT-PCR --- p.43 / Chapter 3.2.2 --- Immunohistochemistry --- p.44 / Chapter 3.2.3 --- Neuron labeling by DiI --- p.45 / Chapter 3.2.4 --- Neuron culture --- p.46 / Chapter 3.2.5 --- [Ca²⁺]i measurement --- p.47 / Chapter 3.2.6 --- Electrophysiology --- p.48 / Chapter 3.2.7 --- Evaluation of baroreflex response --- p.49 / Chapter 3.2.8 --- Telemetric measurement of blood pressure --- p.50 / Chapter 3.2.9 --- Statistical analysis --- p.51 / Figures --- p.52 / Chapter Chapter 4: --- Functional role of TRPC5 channels in aortic baroreceptor --- p.56 / Chapter 4.1 --- Introduction --- p.56 / Chapter 4.2 --- Materials and Methods --- p.59 / Chapter 4.2.1 --- Animals --- p.59 / Chapter 4.2.2 --- Immunohistochemistry --- p.59 / Chapter 4.2.3 --- Neuron labeling by DiI --- p.61 / Chapter 4.2.4 --- Neuron culture --- p.62 / Chapter 4.2.5 --- [Ca²⁺]i measurement --- p.63 / Chapter 4.2.6 --- Electrophysiology --- p.63 / Chapter 4.2.7 --- Evaluation of baroreflex response --- p.64 / Chapter 4.2.8 --- Telemetric measurement of blood pressure --- p.66 / Chapter 4.2.9 --- Statistical analysis --- p.67 / Chapter 4.3 --- Results --- p.67 / Chapter 4.3.1 --- Endogenous expression of TRPC5 channels in aortic baroreceptor neurons --- p.67 / Chapter 4.3.2 --- Characterization on the pressure-sensitive component in aortic baroreceptors --- p.68 / Chapter 4.3.3 --- Involvement of TRPC5 in [Ca²⁺]i response in aortic baroreceptor neurons --- p.69 / Chapter 4.3.4 --- Participation of TRPC5 in pressure-induced action potential firing in cultured aortic baroreceptor neurons --- p.70 / Chapter 4.3.5 --- Role of TRPC5 in baroreceptor sensory nerve activity and baroreflex regulation --- p.71 / Chapter 4.3.6 --- Importance of TRPC5 in baroreceptor function --- p.72 / Chapter 4.4 --- Discussions --- p.74 / Figures --- p.79 / Table --- p.98 / Chapter Chapter --- 5: TRPV4 channels and baroreceptor sensitivity --- p.99 / Chapter 5.1 --- Introduction --- p.99 / Chapter 5.2 --- Materials and Methods --- p.101 / Chapter 5.2.1 --- Animals --- p.101 / Chapter 5.2.2 --- Neuron labeling by DiI --- p.101 / Chapter 5.2.3 --- Neuron culture --- p.102 / Chapter 5.2.4 --- Electrophysiology --- p.103 / Chapter 5.2.5 --- Immunohistochemistry --- p.104 / Chapter 5.2.6 --- [Ca²⁺]i measurement --- p.105 / Chapter 5.2.7 --- Statistical analysis --- p.105 / Chapter 5.3 --- Results --- p.106 / Chapter 5.3.1 --- Properties of the aortic and carotid baroreceptor neurons --- p.106 / Chapter 5.3.2 --- Stretch sensitivity of aortic and carotid baroreceptor neurons --- p.108 / Chapter 5.3.3 --- mRNA expression of mechanosensitive TRP channels in aortic and carotid baroreceptor neurons --- p.109 / Chapter 5.3.4 --- Protein expression of TRPV4 channels in aortic and carotid baroreceptor neurons --- p.109 / Chapter 5.3.5 --- Involvement of TRPV4 in stretch-induced [Ca²⁺]i response in baroreceptor neurons --- p.110 / Chapter 5.4 --- Discussions --- p.111 / Figures --- p.116 / Chapter Chapter 6: --- General conclusions and future directions --- p.124 / Figures --- p.128 / References --- p.133

Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed Sept. 16, 2008). Includes bibliographical references.

Du, Juan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 110-134). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Yau Ho Yan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 131-144). / Abstracts in English and Chinese. / DECLARATION --- p.I / ACKNOWLEDGEMENTS --- p.II / ENGLISH ABSTRACT --- p.III / CHINESE ABSTRACT --- p.VI / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Oxidative Stress --- p.1 / Chapter 1.1.1 --- Historical Background of reactive oxygen/nitrogen species --- p.1 / Chapter 1.1.2 --- What is Oxidative Stress? --- p.3 / Chapter 1.1.3 --- Reactive Oxygen Species (ROS) --- p.4 / Chapter 1.1.3.1 --- Superoxide anion (02-) --- p.4 / Chapter 1.1.3.2 --- Hydrogen peroxide (H202) --- p.5 / Chapter 1.1.3.3 --- Hydroxyl radical --- p.6 / Chapter 1.1.3.4 --- Nitric oxide (NO) --- p.7 / Chapter 1.2 --- Cardiovascular System --- p.8 / Chapter 1.2.1 --- Enzymatic and Non-enzymatic Sources of ROS in Cardiovascular System --- p.8 / Chapter 1.2.1.1 --- NADPH oxidase --- p.8 / Chapter 1.2.1.2 --- Hypoxanthine-Xanthine oxidase (HX-XO) --- p.9 / Chapter 1.2.1.3 --- Nitric oxide synthase (NOS) --- p.10 / Chapter 1.2.1.4 --- Mitochondrial electron transport chain (ETC) --- p.11 / Chapter 1.2.1.5 --- Cyclooxygenase --- p.11 / Chapter 1.2.1.6 --- Lipoxygenae --- p.12 / Chapter 1.2.1.7 --- Endoplasmic reticulum --- p.12 / Chapter 1.2.2 --- ROS/RNS Scavenging Systems --- p.13 / Chapter 1.2.2.1 --- Superoxide dismutase (SOD) --- p.13 / Chapter 1.2.2.2 --- Catalase --- p.14 / Chapter 1.2.2.3 --- Glutathione peroxidase --- p.15 / Chapter 1.2.2.4 --- Non-enzymatic antioxidants --- p.15 / Chapter 1.2.3 --- Factors that stimulate ROS production in cardiovascular system --- p.18 / Chapter 1.2.3.1 --- Oxygen tension --- p.18 / Chapter 1.2.3.2 --- "Flow, Shear, and Stretch as an initial stimulus for endothelial oxidant signalling" --- p.18 / Chapter 1.2.3.3 --- Activation of rennin-angiotensin system promote oxidative stress in cardiovascular system --- p.19 / Chapter 1.2.3.4 --- Regulation of vascular ROS production by vasoactive substances --- p.19 / Chapter 1.2.4 --- Regulation of vascular tone in Cardiovascular System by ROS/RNS --- p.20 / Chapter 1.2.4.1 --- Regulation of vascular tone --- p.20 / Chapter 1.2.5 --- Pathophysiological Effects of ROS --- p.23 / Chapter 1.2.5.1 --- Cellular injury by lipid peroxidation --- p.23 / Chapter 1.2.5.2 --- Role of ROS in immune defence --- p.23 / Chapter 1.2.5.3 --- Redox regulation of cell adhesion --- p.24 / Chapter 1.2.6 --- Evidences from Clinical Studies of Oxidative Stress-Related Vascular Diseases --- p.25 / Chapter 1.2.6.1 --- Hyperlipidaemia --- p.25 / Chapter 1.2.6.2 --- Hypertension --- p.25 / Chapter 1.2.6.3 --- Chronic heart failure (CHF) --- p.26 / Chapter 1.2.6.4 --- Chronic renal failure (CRF) --- p.26 / Chapter 1.2.6.5 --- Atherosclerosis --- p.27 / Chapter 1.2.6.6 --- Ischemia/reperfusion (I/R) injury --- p.27 / Chapter 1.2.7 --- Role of Vascular Endothelium in Oxidative Stress --- p.29 / Chapter 1.2.8 --- Role of Ca in oxidative stress in cardiovascular system --- p.29 / Chapter 1.2.8.1 --- Calcium Signaling in Vascular Endothelial Cells --- p.30 / Chapter 1.2.9 --- ROS effect on endothelial Ca2+ --- p.31 / Chapter 1.2.9.1 --- Multiple targets of ROS on intracellular Ca2+ mobilization --- p.32 / Chapter 1.2.9.2 --- Reports of H202-induced Ca2+ release in various cell types --- p.33 / Chapter 1.2.9.3 --- Reported effects of H202 on agonist-induced Ca2+ signal --- p.34 / Chapter 1.2.9.4 --- Differences between macrovessels and microvessels --- p.34 / Chapter 1.3 --- TRP Channel --- p.41 / Chapter 1.3.1 --- Discovery of Drosophila TRP --- p.41 / Chapter 1.3.2 --- Mammalian TRP subfamily --- p.41 / Chapter 1.3.3 --- General topology of TRP channel --- p.42 / Chapter 1.3.4 --- Interactions of oxidative stress with TRP channels --- p.44 / Chapter 1.3.5 --- The role of TRPC3 and TRPC4 in oxidative stress --- p.44 / Chapter 1.3.6 --- TRPM subfamily --- p.44 / Chapter 1.3.6.1 --- Expression of TRPM2 --- p.45 / Chapter 1.3.6.2 --- Dual Role of TRPM´2ؤChannel and Enzyme --- p.45 / Chapter 1.3.6.3 --- Regulatory mechanisms of TRPM2 --- p.46 / Chapter 1.3.6.3.1 --- ADP-ribose (ADPR) directly regulating --- p.46 / Chapter 1.3.6.3.2 --- NAD regulating --- p.46 / Chapter 1.3.6.3.3 --- Oxidative stress regulating independent of ADPR or NAD --- p.47 / Chapter 1.4 --- Cell Death Induced by Oxidative Stress --- p.48 / Chapter 1.4.1 --- Redox status as a factor to determine cell death --- p.48 / Chapter 1.4.2 --- Role of TRPM2 in oxidative stress-induced cell death --- p.48 / Chapter 1.5 --- Aims of the Study --- p.49 / Chapter Chapter 2: --- Materials and Methods --- p.50 / Chapter 2.1 --- Functional Characterization of TRPM2 by Antisense Technique --- p.50 / Chapter 2.1.1 --- Restriction Enzyme Digestion --- p.50 / Chapter 2.1.2 --- Purification of Released Inserts and Cut pcDNA3 Vectors --- p.51 / Chapter 2.1.3 --- "Ligation of TRPM2 Genes into Mammalian Vector, pcDNA3" --- p.52 / Chapter 2.1.4 --- Transformation for the Desired Clones --- p.52 / Chapter 2.1.5 --- Plasmid DNA Preparation for Transfection --- p.53 / Chapter 2.1.6 --- Confirmation of the Clones --- p.53 / Chapter 2.1.6.1 --- Restriction Enzymes Strategy --- p.53 / Chapter 2.1.6.2 --- Polymerase Chain Reaction (PCR) Check --- p.54 / Chapter 2.1.6.3 --- Automated Sequencing --- p.55 / Chapter 2.2 --- Establishing Stable Cell Lines --- p.56 / Chapter 2.2.1 --- Cell Culture --- p.56 / Chapter 2.2.2 --- Geneticin Selection --- p.57 / Chapter 2.3 --- Expression of TRPM2 in Transfected and non-Transfected H5V Cells --- p.57 / Chapter 2.3.1 --- Protein Sample Preparation --- p.57 / Chapter 2.3.2 --- Western Blot Analysis --- p.58 / Chapter 2.3.3 --- Protein Expression Analysis --- p.59 / Chapter 2.4 --- "Immunolocalization of TRPM2 in Human Heart, Cerebral Artery, Renal, Hippocampus and Liver" --- p.59 / Chapter 2.4.1 --- Paraffin Section Preparation --- p.59 / Chapter 2.4.2 --- Immunohistochemistry --- p.60 / Chapter 2.5 --- [Ca2+ ］i Measurement in Confocal Microscopy --- p.62 / Chapter 2.5.1 --- Cytosolic Ca2+ measurement --- p.62 / Chapter 2.5.2 --- Measuring the Ca2+ in the Internal Calcium Stores --- p.63 / Chapter 2.5.3 --- Data Analysis --- p.64 / Chapter 2.6 --- Examining Cell Death Induced by H2O2 by DAPI Staining --- p.65 / Chapter 2.6.1 --- DAPI Staining --- p.65 / Chapter Chapter 3: --- Results --- p.66 / Chapter 3.1 --- Superoxide Anion-Induced [Ca 2+]i rise in H5V Mouse Heart Microvessel Endothelial Cells --- p.66 / Chapter 3.1.1 --- Superoxide Anion-induced [Ca2+ ]i Rise --- p.66 / Chapter 3.1.2 --- Effect of Catalase on the Superoxide Anion-induced [Ca2+]i］］ Rise --- p.66 / Chapter 3.1.3 --- IP3R inhibitor Inhibits Superoxide anion-induced [Ca 2+]i Rise --- p.67 / Chapter 3.1.4 --- Effect of Phospholipase A2 Inhibitor on Superoxide anion- induced [Ca2+]i Rise --- p.67 / Chapter 3.1.5 --- Effect of Hydroxyl Radical Scavenger on Superoxide Anion- induced [Ca2+]i Rise --- p.68 / Chapter 3.2 --- Hydrogen Peroxide-induced Ca2+ Entry in Mouse Heart Microvessel Endothelial Cells --- p.74 / Chapter 3.2.1 --- Hydrogen Peroxide Induces [Ca2 +]i rise in H5V Mouse Heart Microvessel Endothelial Cells --- p.74 / Chapter 3.2.2 --- Hydrogen Peroxide Induces [Ca 2+]i rise in two phases (Rapid and Slow response) --- p.74 / Chapter 3.2.3 --- Hydrogen Peroxide Induces [Ca 2+]i rise in a Extracellular Ca + Concentration Dependent Manner --- p.77 / Chapter 3.3 --- Hydrogen Peroxide Reduces Agonist-induced [Ca2+]i rise --- p.79 / Chapter 3.3.1 --- Hydrogen Peroxide Reduces ATP-induced [Ca2+ ]i rise in a H2O2 Concentration Dependent Manner --- p.79 / Chapter 3.3.2 --- Hydrogen Peroxide Reduces ATP-induced [Ca 2+]i rise in a H2O2 Incubation Time Dependent Manner --- p.79 / Chapter 3.3.3 --- Hydrogen Peroxide Reduces the ATP-induced Intracellular Ca2+ Release --- p.80 / Chapter 3.3.4 --- XeC Inhibited H202-induced [Ca2+]i rise --- p.80 / Chapter 3.3.5 --- Hydrogen Peroxide Partially Depletes Internal Ca2+ Stores --- p.81 / Chapter 3.4 --- Dissecting Signal Transduction Pathways in H202-induced [Ca2+]i rise --- p.82 / Chapter 3.4.1 --- Effect of Phospholipase C Inhibitor on H202-induced [Ca2 +]i rise --- p.82 / Chapter 3.4.2 --- Effect of Phospholipase A2 Inhibitor on H202-induced [Ca 2+]i rise --- p.83 / Chapter 3.4.3 --- Effect of hydroxyl radical scavenger on H2O2-induced [Ca 2+]i rise --- p.83 / Chapter 3.5 --- Functional Role of TRPM2 Channel in H202-induced [Ca2+]i Rise in H5V Cells --- p.92 / Chapter 3.5.1 --- Expression of TRPM2 and the Effect of TRPM2 Antisense Construct on TRPM2 Protein Expression --- p.92 / Chapter 3.5.2 --- Effect of Antisense TRPM2 on H202-induced Ca2+ Entry --- p.94 / Chapter 3.6 --- H202-induced Cell Death --- p.101 / Chapter 3.7 --- Expression Pattern of TRPM2 Channel in Vascular System --- p.104 / Chapter 3.7.1 --- Immunolocalization of TRPM2 in Human Cerebral Arteries --- p.104 / Chapter 3.7.2 --- Immunolocalization of TRPM2 in Human Cardiac Muscles --- p.105 / Chapter 3.7.3 --- Immunolocalization of TRPM2 in Human Kidney --- p.105 / Chapter Chapter 4: --- Discussion --- p.113 / Chapter 4.1 --- Oxidative modification of Ca2+ homeostasis --- p.113 / Chapter 4.2 --- Pathophysiological effects of ROS on endothelium --- p.113 / Chapter 4.3 --- Effects of ROS on microvascular endothelial Ca2+ reported by other investigators --- p.115 / Chapter 4.4 --- Studies of the effect of HX-XO on cytosolic [Ca2+]i --- p.116 / Chapter 4.4.1 --- Role of 0´2Ø- and H202 in HX-XO-induced [Ca2+]i elevation --- p.116 / Chapter 4.4.2 --- IP3R involvement in HX-XO-evoked Ca + movements in H5V cells --- p.118 / Chapter 4.4.3 --- PLA2 involvement in HX-XO experiment --- p.119 / Chapter 4.5 --- Studies of the effect of direct H202 application on cytosolic [Ca2+]i --- p.120 / Chapter 4.5.1 --- Hydrogen Peroxide Induced [Ca2 +]i rise in a Extracellular Ca2 + Concentration Dependent Manner --- p.120 / Chapter 4.5.2 --- Hydrogen Peroxide Induced [Ca 2+]i rise in two phases (Rapid and Slow response) --- p.121 / Chapter 4.6 --- Effect of H202 on ATP-induced Ca2+ response --- p.121 / Chapter 4.6.1 --- H202 inhibited ATP-induced Ca2+ release in a concentration and time dependent manner --- p.121 / Chapter 4.6.2 --- IP3R involvement and store depletion in H202 experiment --- p.123 / Chapter 4.7 --- Dissecting Signal Transduction Pathways in H202-induced [Ca2+]i rise --- p.124 / Chapter 4.7.1 --- PLC involvement in H2O2 experiment --- p.124 / Chapter 4.7.2 --- PLA2 involvement in H2O2 experiment --- p.125 / Chapter 4.7.3 --- Hydroxyl radical did not involve in H2O2 experiment --- p.125 / Chapter 4.8 --- Functional Studies of TRPM2 --- p.127 / Chapter 4.8.1 --- Expression of TRPM2 in H5V on protein level --- p.127 / Chapter 4.8.2 --- TRPM2 involvement in the Ca2+ signalling in response to H2O2 in H5V cells --- p.127 / Chapter 4.9 --- H202 concentration in my projec´tؤphysiological or pathological? --- p.128 / Chapter 4.10. --- H20´2ؤTRPM´2ؤCell death --- p.129 / Chapter 4.11 --- Expression of TRPM2 in human blood vessels and other tissues --- p.130 / References --- p.131

Kwan Hiu Yee. / "June 2006." / 2+ in the title is superscript. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 131-150). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.

Feeding is one of the most important behaviors for an animal’s survival. At a gross level, it is known that the nervous system plays a major role in the expression of this complex behavior, yet a detailed understanding of the neural circuits directing feeding behavior remains unknown. Here we identify a command neuron in Drosophila melanogaster whose artificial activation, using dTrpA1, a heat-activated cation channel, induces the appearance of complete feeding behavior. We use behavioral, genetic, cellular and optical imaging techniques to show that the induced behavior is composed of multiple motor programs and can function to uptake exogenous, even noxious, material. Furthermore, we resolve the neuron’s location to the subesophageal ganglion, characterize its pre and post-synaptic sites, and determine its responsiveness to sucrose stimulation. Interestingly, the neuron’s dendritic field is proximal to sweet sensing axon terminals and its baseline activity corresponds to the fly’s satiation state, suggesting a potential point of integration between sensory, motor and motivational systems. The identification of a command neuron for feeding in a genetically tractable organism provides a useful model to develop a deeper understanding of the neural control of this ubiquitous and evolutionarily ancient behavior.

Introdução. A hiperativação nervosa simpática é característica marcante da insuficiência cardíaca. Estudos apontam alterações no controle ergorreflexo muscular (mecano e metaborreflexo) como mecanismos potenciais para explicar esta modificação autonômica. Os mecanorreceptores (fibras do grupo III), que são ativadas pelo aumento no tônus muscular e modulados por metabólitos da via das ciclooxigenases, encontram-se hipersensibilizadas na insuficiência cardíaca. Ao contrário, a sensibilidade dos metaborreceptores (fibras do grupo IV), que são ativados pelo acúmulo de metabólitos durante as contrações musculares e modulados pelos receptores TRPV1 e CB1, encontra-se diminuída na insuficiência cardíaca. Por outro lado, o treinamento físico tem se mostrado uma importante ferramenta no tratamento da insuficiência cardíaca. Ele reduz os níveis de atividade nervosa simpática muscular (ANSM) no repouso e durante o exercício em pacientes portadores desta síndrome. Dessa forma, neste estudo, nós testamos a hipótese de que o treinamento físico melhoraria o controle mecano e metaborreflexo da ANSM em pacientes com insuficiência cardíaca, e se essa melhora está associada às alterações na via das ciclooxigenases e na expressão dos receptores TRPV1 e CB1, respectivamente. Métodos. Pacientes com insuficiência cardíaca foram consecutivamente e aleatoriamente divididos em dois grupos: insuficiência cardíaca não treinado (ICNT, n=17) e insuficiência cardíaca treinado (ICT, n=17). A ANSM foi avaliada pela técnica de microneurografia e o fluxo sanguíneo muscular (FSM) pela pletismografia de oclusão venosa. A frequência cardíaca (FC) e a pressão arterial (PA) foram avaliadas por medida não invasiva a cada batimento (Finometer). Foi realizada biopsia muscular do vasto lateral para análise de expressão gênica. O treinamento físico aeróbio foi realizado em ciclo ergômetro, em intensidade moderada, por 40 minutos, três vezes por semana, durante 16 semanas. A sensibilidade mecanorreflexa foi calculada pelo delta absoluto entre o pico do exercício passivo, realizado na perna esquerda, e a média do registro basal. A sensibilidade metaborreflexa foi calculada pelo delta absoluto entre o 1º minuto de oclusão circulatória pós-exercício na perna esquerda e a média do registro basal. Resultados. O treinamento físico reduziu a ANSM e aumentou o FSM no repouso. O treinamento físico diminuiu significativamente as respostas de ANSM durante o exercício passivo no grupo ICT. As repostas de PA média também foram menores no grupo ICT quando comparado ao grupo ICNT. Não houve alterações significativas nas repostas de FC, PA sistólica, PA diastólica e FSM durante o exercício passivo no grupo ICT. Em relação à sensibilidade metaborreflexa, o treinamento físico aumentou expressivamente as respostas de ANSM no 1º minuto de oclusão circulatória no grupo ICT. As respostas de FC, PA e FSM não foram alteradas neste grupo. Não foram observadas alterações significativas nos controles mecano e metaborreflexo musculares no grupo ICNT. Além disso, o treinamento físico reduziu significativamente a expressão gênica da enzima COX-2 e do receptor EP4 e aumentou significativamente a expressão dos receptores TRPV1 e CB1 no grupo ICT. Não foram verificadas alterações significativas nas expressões gênicas do grupo ICNT. Conclusões. O treinamento físico normaliza os controles mecano e metaborreflexo da ANSM em pacientes com insuficiência cardíaca. Estas alterações podem estar associadas às alterações na expressão gênica da enzima COX-2 e receptor EP4, e dos receptores TRPV1 e CB1, respectivamente. Em conjunto, estes achados podem explicar, pelo menos em parte, a diminuição da atividade nervosa simpática e a melhora na tolerância aos esforços em pacientes com insuficiência cardíaca / Introduction. Sympathoexcitation is the hallmark of heart failure. Studies suggest changes in ergoreflex muscle control (mechanoreflex and metaboreflex) as potential mechanisms to explain this autonomic alteration in heart failure. Mechanoreceptors (group III fibers) that are activated by mechanical stimuli and modulated by cyclooxygenase pathway metabolites are hypersensitive in heart failure. In contrast, the sensitivity of metaboreceptors fibers (group IV) that are activated by increases in ischemic metabolites during muscle contractions and modulated by TRPV1 and CB1 receptors is blunted in heart failure. On the other hands, exercise training has been shown to be an important strategy in the treatment of heart failure. It reduces the levels of muscle sympathetic nerve activity (MSNA) at rest and during exercise in patients suffering of this syndrome. Thus, we tested the hypothesis that exercise training would improve the mechanoreflex and metaboreflex control of MSNA in heart failure patients. In addition, we investigated whether the improvement in the mechanoreflex and metaboreflex control is related to changes in the cyclooxygenase pathway and expression of TRPV1 and CB1 receptors, respectively. Methods. Patients with heart failure were consecutively and randomly divided into two groups: heart failure untrained (HFUT, n = 17) and heart failure exercise-trained (HFET, n = 17). MSNA was measured by microneurography technique and muscle blood flow (MBF) by venous occlusion plethysmography. Heart rate (HR) and blood pressure (BP) were assessed by noninvasive measure on a beat-to-beat basis (Finometer). Gene expression analysis was investigated by vastus lateralis muscle biopsy. Aerobic exercise training was performed on a cycle ergometer at moderate intensity, three 40-min session/wk for 16 weeks. Mechanoreflex sensitivity was evaluated by means the absolute difference in MSNA at peak passive exercise and baseline. Metaboreflex sensitivity was calculated by means the absolute difference in MSNA at 1st min after exercise period with muscle circulatory arrest and baseline. Results. Exercise training reduced MSNA and increased MBF. Exercise training significantly decreased MSNA responses during passive exercise. The mean BP response was lower in HFET group when compared to HFUT group. There were no significant changes in HR, systolic and diastolic BP and MBF responses during passive exercise in HFET group. Regarding metaboreflex sensitivity, exercise training significantly increased the MSNA responses at 1st minute of post exercise circulatory arrest. The responses of HR, BP and MBF were unchanged after exercise training. No significant changes were observed in mechanoreflex and metaboreflex control in the HFUT group. Furthermore, exercise training significantly reduced gene expression of COX-2 and EP4 receptor and significantly increased expression of TRPV1 and CB1 receptors. There were no significant changes in the gene expressions in the HFUT group. Conclusions. Exercise training improves mechanoreflex and metaboreflex control of MSNA in heart failure patients. These changes may be associated with changes in gene expression of COX-2 and EP4 receptor and TRPV1 and CB1 receptor, respectively. Together, these findings may explain, at least in part, the decrease in sympathetic nerve activity and the improvement in exercise tolerance in patients with heart failure

Introdução. A hiperativação nervosa simpática é característica marcante da insuficiência cardíaca. Estudos apontam alterações no controle ergorreflexo muscular (mecano e metaborreflexo) como mecanismos potenciais para explicar esta modificação autonômica. Os mecanorreceptores (fibras do grupo III), que são ativadas pelo aumento no tônus muscular e modulados por metabólitos da via das ciclooxigenases, encontram-se hipersensibilizadas na insuficiência cardíaca. Ao contrário, a sensibilidade dos metaborreceptores (fibras do grupo IV), que são ativados pelo acúmulo de metabólitos durante as contrações musculares e modulados pelos receptores TRPV1 e CB1, encontra-se diminuída na insuficiência cardíaca. Por outro lado, o treinamento físico tem se mostrado uma importante ferramenta no tratamento da insuficiência cardíaca. Ele reduz os níveis de atividade nervosa simpática muscular (ANSM) no repouso e durante o exercício em pacientes portadores desta síndrome. Dessa forma, neste estudo, nós testamos a hipótese de que o treinamento físico melhoraria o controle mecano e metaborreflexo da ANSM em pacientes com insuficiência cardíaca, e se essa melhora está associada às alterações na via das ciclooxigenases e na expressão dos receptores TRPV1 e CB1, respectivamente. Métodos. Pacientes com insuficiência cardíaca foram consecutivamente e aleatoriamente divididos em dois grupos: insuficiência cardíaca não treinado (ICNT, n=17) e insuficiência cardíaca treinado (ICT, n=17). A ANSM foi avaliada pela técnica de microneurografia e o fluxo sanguíneo muscular (FSM) pela pletismografia de oclusão venosa. A frequência cardíaca (FC) e a pressão arterial (PA) foram avaliadas por medida não invasiva a cada batimento (Finometer). Foi realizada biopsia muscular do vasto lateral para análise de expressão gênica. O treinamento físico aeróbio foi realizado em ciclo ergômetro, em intensidade moderada, por 40 minutos, três vezes por semana, durante 16 semanas. A sensibilidade mecanorreflexa foi calculada pelo delta absoluto entre o pico do exercício passivo, realizado na perna esquerda, e a média do registro basal. A sensibilidade metaborreflexa foi calculada pelo delta absoluto entre o 1º minuto de oclusão circulatória pós-exercício na perna esquerda e a média do registro basal. Resultados. O treinamento físico reduziu a ANSM e aumentou o FSM no repouso. O treinamento físico diminuiu significativamente as respostas de ANSM durante o exercício passivo no grupo ICT. As repostas de PA média também foram menores no grupo ICT quando comparado ao grupo ICNT. Não houve alterações significativas nas repostas de FC, PA sistólica, PA diastólica e FSM durante o exercício passivo no grupo ICT. Em relação à sensibilidade metaborreflexa, o treinamento físico aumentou expressivamente as respostas de ANSM no 1º minuto de oclusão circulatória no grupo ICT. As respostas de FC, PA e FSM não foram alteradas neste grupo. Não foram observadas alterações significativas nos controles mecano e metaborreflexo musculares no grupo ICNT. Além disso, o treinamento físico reduziu significativamente a expressão gênica da enzima COX-2 e do receptor EP4 e aumentou significativamente a expressão dos receptores TRPV1 e CB1 no grupo ICT. Não foram verificadas alterações significativas nas expressões gênicas do grupo ICNT. Conclusões. O treinamento físico normaliza os controles mecano e metaborreflexo da ANSM em pacientes com insuficiência cardíaca. Estas alterações podem estar associadas às alterações na expressão gênica da enzima COX-2 e receptor EP4, e dos receptores TRPV1 e CB1, respectivamente. Em conjunto, estes achados podem explicar, pelo menos em parte, a diminuição da atividade nervosa simpática e a melhora na tolerância aos esforços em pacientes com insuficiência cardíaca / Introduction. Sympathoexcitation is the hallmark of heart failure. Studies suggest changes in ergoreflex muscle control (mechanoreflex and metaboreflex) as potential mechanisms to explain this autonomic alteration in heart failure. Mechanoreceptors (group III fibers) that are activated by mechanical stimuli and modulated by cyclooxygenase pathway metabolites are hypersensitive in heart failure. In contrast, the sensitivity of metaboreceptors fibers (group IV) that are activated by increases in ischemic metabolites during muscle contractions and modulated by TRPV1 and CB1 receptors is blunted in heart failure. On the other hands, exercise training has been shown to be an important strategy in the treatment of heart failure. It reduces the levels of muscle sympathetic nerve activity (MSNA) at rest and during exercise in patients suffering of this syndrome. Thus, we tested the hypothesis that exercise training would improve the mechanoreflex and metaboreflex control of MSNA in heart failure patients. In addition, we investigated whether the improvement in the mechanoreflex and metaboreflex control is related to changes in the cyclooxygenase pathway and expression of TRPV1 and CB1 receptors, respectively. Methods. Patients with heart failure were consecutively and randomly divided into two groups: heart failure untrained (HFUT, n = 17) and heart failure exercise-trained (HFET, n = 17). MSNA was measured by microneurography technique and muscle blood flow (MBF) by venous occlusion plethysmography. Heart rate (HR) and blood pressure (BP) were assessed by noninvasive measure on a beat-to-beat basis (Finometer). Gene expression analysis was investigated by vastus lateralis muscle biopsy. Aerobic exercise training was performed on a cycle ergometer at moderate intensity, three 40-min session/wk for 16 weeks. Mechanoreflex sensitivity was evaluated by means the absolute difference in MSNA at peak passive exercise and baseline. Metaboreflex sensitivity was calculated by means the absolute difference in MSNA at 1st min after exercise period with muscle circulatory arrest and baseline. Results. Exercise training reduced MSNA and increased MBF. Exercise training significantly decreased MSNA responses during passive exercise. The mean BP response was lower in HFET group when compared to HFUT group. There were no significant changes in HR, systolic and diastolic BP and MBF responses during passive exercise in HFET group. Regarding metaboreflex sensitivity, exercise training significantly increased the MSNA responses at 1st minute of post exercise circulatory arrest. The responses of HR, BP and MBF were unchanged after exercise training. No significant changes were observed in mechanoreflex and metaboreflex control in the HFUT group. Furthermore, exercise training significantly reduced gene expression of COX-2 and EP4 receptor and significantly increased expression of TRPV1 and CB1 receptors. There were no significant changes in the gene expressions in the HFUT group. Conclusions. Exercise training improves mechanoreflex and metaboreflex control of MSNA in heart failure patients. These changes may be associated with changes in gene expression of COX-2 and EP4 receptor and TRPV1 and CB1 receptor, respectively. Together, these findings may explain, at least in part, the decrease in sympathetic nerve activity and the improvement in exercise tolerance in patients with heart failure