Orientador: Paulo Cesar Rodrigues Palma / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-04T10:03:35Z (GMT). No. of bitstreams: 1 Dambros_Miriam_D.pdf: 5436149 bytes, checksum: adcf62040b0e93aa24e7479ee60c4ebb (MD5) Previous issue date: 2005 / Resumo: Os agentes antimuscarínicos permanecem como drogas de primeira linha para o tratamento da Síndrome da Bexiga Hiperativa (SBH), a despeito das dúvidas ainda existentes sobre a significância clínica e sua eficácia. Poucos fármacos que atuam por meio de mecanismos distintos dos antimuscarínicos, têm demonstrado eficácia no tratamento da SBH. Ravonóides são um grupo de compostos polifenólicos que têm recebido especial atenção dentro da pesquisa básica e clínica devido ao seu amplo espectro de atividade farmacológica. Recentemente, um estudo in vitro demonstrou que o fIavonóide galangina exerce uma atividade inibitória sobre a contratilidade da bexiga de ratos. Esta tese foi desenvolvida a fim de examinar os efeitos da galangina sobre a resposta contrátil da bexiga de suínos e testar a hipótese de um efeito sobre a mobilização do cálcio. Além disso, investigou-se a eficácia da galangina em promover uma ação protetora sobre o dano da musculatura lisa da bexiga causada por um período de estimulação elétrica repetitiva, o qual é empregado como um modelo, in vitro, de hiperrefIexia. Em um grupo de experimentos, fragmentos do detrusor de suínos foram submetidos a um período de 90 mÍn de estimulação elétrica de repetição. Galangina, em diferentes concentrações, foi adicionada ao banho do órgão a fim de determinar seu possível efeito protetor durante a estimulação elétrica. Em outro grupo de experimentos, a resposta contrátil ao carbacol, cafeína, potássio e eletroestímulo foi determinada antes e após a adição de galangina (3xl0-sM) ao meio. Os efeitos do fIavonóide foram também avaliados após a administração de diferentes antagonistas no banho de órgão. Galangina (1O-7M) evitou o decréscimo da resposta contrátil do músculo liso causada por um período de estimulação elétrica de repetição. vesical Galangina inibiu a amplitude da contração detrusora induzi da pelo eletro-estímulo, carbacol, cafeína e potássio (p<0.05). O efeito inibitório do fIavonóide foi deixado inalterado após a introdução de diferentes antagonistas: propranolol, fentolamina e capsazepina, no banho de órgão (p>0,05). Entretanto, quando verapamil foi adicionado ao meio de estudo, a inibição da contração foi parcialmente abolida. Concluindo, os experimentos acima descritos demonstraram que a galangina, em concentração nanomolar, exerceu um efeito protetor sobre a musculatura detrusora. Entretanto, quando empregado em uma concentração micromolar, o flavonóide promoveu einibição da musculatura lisa vesical, o qual resultou de uma ação sobre a mobilização do cálcio extra e intracelular / Abstract: Antimuscarinjc agents remain first-line therapy for the overactive bladder syndrome (OAB), despite doubts about the clinjcal signifjcance of their effectiveness. Few drugs acting through other mechanisms have been found to be efficacious for treatment of GAB. Flavonoids are a group of polyphenolic compounds and have recently gained tremendous interest, due to their broad pharmacologjcal activity. Recently, the inhibitory effect of galangin, a member of the flavonol class of flavonoid, on rat bladder contractility has been investigated. This thesis was undertaken to further examine the actions of galangin on the contractile responses of bladder strips and to test the hypothesis that an effect on calcium mobilization in smooth muscle cells is involved. Furthermore, it was investigated the efficacy of galangin to counteract the detrusor damage caused by the smooth muscle of the urinary bladder being exposed to repetitive field stimulation (RFS), as a model of hyperreflexia. In one experiment, pig detrusor strips were mounted for tension recording in organ baths and were subjected to RFS for 90min. Galangin, at different concentrations, was added to the organ bath in order to determine its protective effect on RFS. In another experiment the contractile response to carbachol, potassium and electrical field stimulation - EFS were determined before and after the addition of galangin (3xlO-sM). Furthermore, the effect of galangin was also evaluated after the administration in the bath of a number of antagonists. Galangin (1O-7M)avoided the decrease in contractile smooth muscle response of strips to EFS during RFS. Galangin inhibited the maximal contractile response to EFS, carbachol, caffeine media and potassium (pO,O5).However, when verapamil was added to the medium, the inhibitory effects of galangin were partially blocked. In summary, the current experiments have shown that galangin, in subllmol concentrations, exerted a protective effect on bladder smooth muscle contractility. Furthermore, galangin, in !lIDO!concentrations inhibited pig bladder contractility, which probably resulted from an action on Ca2+mobilization from intracellu!ar stores as well as influx of calcium. At the present, there is no proof that our results are reproducible in functional or dysfunctional human bladders. Further study is needed to investigate the potential of ga!anginto be used to inhibited overactive bladder syndrome in vivo / Doutorado / Cirurgia / Doutor em Cirurgia

Calcium-activated chloride channels (CaCCs) are ubiquitously expressed in a plethora of cell types and, consequently, are involved in numerous cellular processes as diverse as epithelial secretion, regulation of cardiac excitability and smooth muscle contraction. Current pharmacology of CaCCs is limited to compounds with low potency and poor selectivity. The lack of knowledge surrounding the molecular identity of the CaCC has greatly hindered the development of more specific drugs and has impaired our understanding of the channel physiology and biophysics. The recent discovery that the TMEM16A gene codes for CaCCs has offered hope for new developments in these areas. CaCCs have been suggested as possible targets to treat a variety of conditions including asthma as well as pulmonary and systemic hypertension. Due to the ubiquitous expression of CaCCs and the ability of the channel to interact with a number of pharmacological compounds with diverse chemical structures however, it was hypothesised that TMEM16A could be a possible source for off-target drug effects and may represent a concern for safety pharmacology. The principal aim of this thesis was to assess the functional significance of TMEM16A in the cardiovascular system, as this is one of the major systems of concern for safety pharmacology and accounts for the largest number of post-market drug withdrawals. The main findings of this study can be summarised as follows: 1) RT-PCR analysis revealed a ubiquitous expression of TMEM16A in tissues of the rat and human cardiovascular systems, including systemic and pulmonary arteries as well as cardiac tissue. Analysis also revealed the presence of multiple TMEM16A splice variants in all rat tissues examined, in addition to a number of other TMEM16x family members. 2) Myography experiments using the “classical” CaCC blocker niflumic acid and newly identified TMEM16A blockers confirmed a functional role for TMEM16A in phenylephrine-induced vascular smooth muscle contraction. 3) The suitability of currently available Cl- channel blockers for use as pharmacological tools for TMEM16A research was assessed using conventional whole-cell patch clamp and high-throughput electrophysiology techniques to respectively compare their potencies and selectivity over other cardiovascular ion channels. Of the compounds tested, DIDS and T16Ainh-A01 appeared the most suitable blockers; however all compounds had a degree of non-selectivity, raising concerns for their use in functional studies. In conclusion, these findings provide evidence for the ubiquitous expression and functional significance of TMEM16A within the cardiovascular system and support the hypothesis that TMEM16A is a concern for safety pharmacology and should be included into future pre-clinical safety assays. The inadequacy of current inhibitors however highlights the urgency for the development of novel potent and selective channel modulators for future TMEM16A research.

Plasma membrane calcium ATPase 4 (PMCA4) is a calcium extrusion pump which may also modulate Ca2+-triggered signal transduction pathways. Previous studies postulate that PMCA4 modulates signalling via an interaction with neuronal nitric oxide synthase (nNOS) in localised plasmalemmal microdomains. The effect of PMCA4 on vascular contractility is unclear. This project has utilised PMCA4 ablated mice (PMCA4 KO (-/-)) and a novel specific PMCA4 inhibitor (termed AP2) to study the role of PMCA4 in mouse resistance artery contractility.Immunohistochemistry, Western blotting and polymerase chain reaction (PCR) confirmed the absence of PMCA4 in the brain, vasculature and ear snips obtained from PMCA4 KO (-/-) mice whereas it was present in those from wild type (WT (+/+)) mice. Pressure myography was employed to assesss contractile function of isolated, pressurised (to 60 mmHg) mesenteric resistance arteries from 3 months old male PMCA4 KO (-/-) and WT (+/+) mice, in response to high K+ physiological salt solution (KPSS) (40mM & 100mM) and noradrenaline (NA) (Log[NA] -9.0 to -5.0M). Passive lumen diameter and left and right wall thicknesses of arteries from PMAC4 KO (-/-) and WT (+/+) mice were taken at transmural pressures of 5-140 mmHg. Effects of acute PMCA4 inhibition with AP2 (10µM and 1µM), nitric oxide synthase (NOS) inhibition with LNNA (100µM) and specific nNOS inhibition with Vinyl-L-Nio (10µM) were also investigated. Effects of PMCA4 ablation and AP2 (10µM) on global intracellular Ca2+ changes ([Ca2+]i) in pressurised mesenteric arteries were assessed after loading arteries with the Ca2+-sensitive indicator indo-1. PMCA4 ablation had no effect on the magnitude of arterial constrictions or on the changes of [Ca2+]i in response to KPSS (40mM & 100mM) or to noradrenaline. The passive intra-lumen diameter, wall thickness, wall to lumen diameter and cross sectional area of mesenteric arteries across the intravascular pressure range studied were also not modulated by PMCA4 ablation. A leftwards shift in the stress to strain relationship and significant increase in beta elastic modulus (β) were revealed in arteries from PMCA4 KO (-/-) mice compared to those from WT (+/+) mice, suggesting that PMCA4 ablation reduces mesenteric arterial distensibility. Acute PMCA4 inhibition with AP2, significantly reduced arterial constrictions and the increase in [Ca2+]i in response to noradrenaline in arteries from WT (+/+) mice, but had no effect on arterial constrictions elicited by arteries from PMCA4 KO (-/-) mice. Inhibitory effects of AP2 were not present in arteries after NOS inhibition by LNNA and also after nNOS inhibition with Vinly-L-Nio. Hence, PMCA4 inhibition with AP2 reduces vascular constriction by a nNOS-dependent mechanism.In conclusion, the main findings of the study were that ablation and acute inhibition of PMCA4 with AP2 have different effects on mouse mesenteric resistance arterial contractility. This study provides more insight into PMCA4 as a significant modulator of signalling within the vasculature via effects on nNOS.

The interaction between CD40 ligand (CD154) expressed on activated T cells and its receptor, CD40, has been shown to play a role in the onset and maintenance of autoimmune inflammation. Recent studies suggest that CD154+T cells also contribute to the regulation of atherogenesis due to their capacity to activate CD40+cells of the vasculature, including vascular smooth muscle cells (VSMC). The present study evaluated the signalling events initiated through CD40 ligation which culminate in VSMC chemokine production. CD40 ligation resulted in the phosphorylation/activation of mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinases 1 and 2 (ERK1/2), and p38, but not c-jun N-terminal kinase. Inhibition of both ERK1/2 and p38 activity abrogated CD40 stimulation of IL-8 and MCP-1 production. CD40-mediated induction of chemokines also showed dependence on the Src family kinase activity. The Src kinase inhibitor, PP2, was found to inhibit CD40-induced phosphorylation of ERK1/2 as well as activation of IκB kinase. An evaluation of Src kinases that may be important in CD40 signalling identified Lyn as a potential candidate. These data indicate that CD40 signalling in VSMC activates a Src family kinase-initiated pathway that results in the induction of MAPK activities required for successful induction of chemokine synthesis.

This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).

1. We studied the effect of intracellular angiotensin II (Ang II) and related peptides on rat aortic contraction, whether this effect is pharmacologically distinguishable from that induced by extracellular stimulation, and determined the Ca2+ source involved. 2. Compounds were delivered into the cytoplasm of de-endothelized aorta rings using multilamellar liposomes. Contractions were normalized to the maximum obtained with phenylephrine (10-5 M). 3. Intracellular administration of Ang II (incorporation range: 0.01-300 nmol mg-1) resulted in a dose-dependent contraction, insensitive to extracellular administration (10-6 M) of the AT1 receptor antagonist CV11947, the AT2 receptor antagonist PD 123319, or the non-selective AT receptor antagonist and partial agonist saralasin ([Sar1,Val5,Ala8]-Ang II (P < 0.05). 4. Intracellular administration of CV11947 or PD 123319 right shifted the dose-response curve about 1000 fold or 20 fold, respectively. PD 123319 was only effective if less than 30 nmol mg-1 Ang II was incorporated. 5. Contraction was partially desensitized to a second intracellular Ang II addition after 45 min (P < 0.05). 6. Intracellular administration of Ang I and saralasin also induced contraction (P < 0.05). Both responses were sensitive to intracellular CV11947 (P < 0.05), but insensitive to PD 123319. The response to Ang I was independent of intracellular captopril. 7. Contraction induced by extracellular application of Ang II and of Ang I was abolished by extracellular pre-treatment with saralasin or CV11947 (P < 0.05), but not with PD 123319. Extracellular saralasin induced no contraction. 8. Intracellular Ang II induced contraction was not affected by pre-treatment with heparin filled liposomes, but completely abolished in Ca2+-free external medium. 9. These results support the existence of an intracellular binding site for Ang II in rat aorta. Intracellular stimulation induces contraction dependent on Ca2+-influx but not on Ins(1,4,5)P3 mediated release from intracellular Ca2+-stores. Intracellular Ang I and saralasin induce contraction, possibly via the same binding site. Pharmacological properties of this putative intracellular receptor are clearly different from extracellular stimulated AT1 receptors or intracellular angiotensin receptors postulated in other tissue.

No description available.

L-type Ca2+ channels, found in vascular smooth muscle cells, function to control Ca2+ influx, which directly regulates the degree of tension in the vasculature. An influx of Ca2+ causes these cells to contract while inhibition of this channel causes muscle relaxation, a major goal in treating hypertension. Acute hypoxia inhibits, and chronic hypoxia enhances, Ca2+ channel currents. The mechanisms underlying these hypoxic responses were examined in HEK 293 cells by altering cellular levels of proposed mediators of 0 2 sensing which have previously been shown to be involved in the redox model of 02 sensing in various cell types. In these studies I investigated the roles of mitochondrial complexes and NADPH oxidase function, and changes in cellular ROS levels, on the acute and chronically hypoxic regulation of recombinant L-type Ca2+ channels. An increase in H202, a form of ROS, by exogenous application was found to enhance Ca2+ currents. However neither catalase nor H202 affected the acute hypoxic response. In contrast superoxide dismutase (SOD) abolished hypoxic inhibition of recombinant L-type Ca2+ channels, suggestive of a role of 02- production in 02 sensing. Altered production of this ROS during hypoxia may occur within the mitochondria since acute 02 sensing was abolished in mitochondria-depleted p0 cells. Alterations in NADPH oxidase activity via application of NADPH oxidase inhibitors such as DPl and P AO did not mediate the acute hypoxic response. Hypoxic regulation of mitochondrial complex I may also mediate the response to chronic hypoxia since current enhancement by this stimulus was abolished by rotenone. These findings support the involvement of altered mitochondrial function in the 0 2 sensing pathway which mediates the hypoxic responses of recombinant L-type Ca2+ channel a1c subunits. / Thesis / Master of Science (MSc)

Yes / Induction of the antioxidant enzyme heme oxygenase-1 (HO-1) affords cellular protection and suppresses proliferation of vascular smooth muscle cells (VSMCs) associated with a variety of pathological cardiovascular conditions including myocardial infarction and vascular injury. However, the underlying mechanisms are not fully understood. Over-expression of Cav3.2 T-type Ca2+ channels in HEK293 cells raised basal [Ca2+]i and increased proliferation as compared with non-transfected cells. Proliferation and [Ca2+]i levels were reduced to levels seen in non-transfected cells either by induction of HO-1 or exposure of cells to the HO-1 product, carbon monoxide (CO) (applied as the CO releasing molecule, CORM-3). In the aortic VSMC line A7r5, proliferation was also inhibited by induction of HO-1 or by exposure of cells to CO, and patch-clamp recordings indicated that CO inhibited T-type (as well as L-type) Ca2+ currents in these cells. Finally, in human saphenous vein smooth muscle cells, proliferation was reduced by T-type channel inhibition or by HO-1 induction or CO exposure. The effects of T-type channel blockade and HO-1 induction were non-additive. Collectively, these data indicate that HO-1 regulates proliferation via CO-mediated inhibition of T-type Ca2+ channels. This signalling pathway provides a novel means by which proliferation of VSMCs (and other cells) may be regulated therapeutically. / This work was supported by the British Heart Foundation.

OBJECTIVE:Vascular smooth muscle cell (VSMC) hypertrophy and proliferation occur in response to strain-induced local and systemic inflammatory cytokines and growth factors which may contribute to hypertension, atherosclerosis, and restenosis. We hypothesize VSMC strain, modeling normotensive arterial pressure waveforms in vitro, results in attenuated proliferative and increased hypertrophic responses 48 hrs post-strain.METHODS:Using Flexcell Bioflex Systems we determined the morphological, hyperplastic and hypertrophic responses of non-strained and biomechanically strained cultured rat A7R5 VSMC. We measured secretion of nitric oxide, key cytokine/growth factors and intracellular mediators involved in VSMC proliferation via fluorescence spectroscopy and protein microarrays. We also investigated the potential roles of VEGF on VSMC strain-induced proliferation.RESULTS:Protein microarrays revealed significant increases in VEGF secretion in response to 18 hours mechanical strain, a result that ELISA data corroborated. Apoptosis-inducing nitric oxide (NO) levels also increased 43% 48 hrs post-strain. Non-strained cells incubated with exogenous VEGF did not reproduce the antimitogenic effect. However, anti-VEGF reversed the antimitogenic effect of mechanical strain. Antibody microarrays of strained VSMC lysates revealed MEK1, MEK2, phospo-MEK1T385, T291, T298, phospho-Erk1/2T202+Y204/T185+T187, and PKC isoforms expression were universally increased, suggesting a proliferative/inflammatory signaling state. Conversely, VSMC strain decreased expression levels of Cdk1, Cdk2, Cdk4, and Cdk6 by 25-50% suggesting a partially inhibited proliferative signaling cascade.CONCLUSIONS:Subjecting VSMC to cyclic biomechanical strain in vitro promotes cell hypertrophy while attenuating cellular proliferation. We also report an upregulation of MEK and ERK activation suggestive of a proliferative phenotype. Hhowever, the proliferative response appears to be aborogated by enhanced antimitogenic cytokine VEGF, NO secretion and downregulation of Cdk expression. Although exogenous VEGF alone is not sufficient to promote the quiescent VSMC phenotype, we provide evidence suggesting that strain is a necessary component to induce VSMC response to the antimitogenic effects of VEGF. Taken together these data indicate that VEGF plays a critical role in mechanical strain-induced VSMC proliferation and vessel wall remodeling. Whether VEGF and/or NO inhibit signaling distal to Erk 1/2 is currently under investigation.