Thesis (Ph. D. in Molecular Physiology and Biophysics)--Vanderbilt University, Dec. 2006. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)-University of Washington, 1998. / Vita. Includes bibliographical references (leaves [67]-81).

Thesis (Ph. D.)--University of Chicago, Dept. of Neurobiology, Pharmacology and Physiology. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [64]-71).

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaves 33-35). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Chicago, Dept. of Pharmacological and Physiological Sciences, August 1999. / Includes bibliographical references. Also available on the Internet.

Myocardial reperfusion injury is thought to be caused by reperfusion induced i) cytosolic Ca²⁺ overload and/or, ii) the formation of oxygen derived freeradicals. At the start of this study, data implicating cytosolic Ca²⁺ overload in the genesis of reversible reperfusion injury were inconclusive. Although several workers have approached this problem by measurements of cytosolic calcium ions, it was my aim to examine the potential sources of such calcium overload. The experiments reported in this thesis were therefore designed to examine the role of altered intracellular and transsarcolemmal Ca²⁺ fluxes in the genesis of reperfusion stunning and arrhythmias. The study was also aimed at elucidating the possible sources and entry pathways contributing to this proposed cytosolic Ca²⁺ overload. In order to investigate the possible role of altered reperfusion Ca²⁺ fluxes in reperfusion injury, we exposed the isolated working, and Langendorff perfused rat heart model to ischaemia and reperfusion to induce reperfusion stunning and arrhythmias. Hearts were pre-treated (before ischaemia) or reperfused with pharmacological compounds, or by interventions known to enhance or inhibit intracellular or transsarcolemmal Ca²⁺ fluxes. The severity of reperfusion stunning (mechanical dysfunction) was measured by reperfusion aortic output, coronary flow and left ventricular pressure. The incidence of reperfusion ventricular arrhythmias was measured by the incidence of ventricular tachycardia and/ or fibrillation. In selected studies, the metabolic status of hearts was evaluated using biochemical assays performed on myocardial tissue samples. Data obtained in these studies indicate that increased Ca²⁺ fluxes through sarcolemmal L-type Ca²⁺ channels during early reperfusion exacerbate stunning, while inhibition of these fluxes with the Ca²⁺ antagonist drug nisoldipine or by Mg²⁺ or Mn²⁺ improve reperfusion function. These data also suggest that although interventions increasing Ca²⁺ fluxes early in reperfusion exacerbate reperfusion stunning, these same interventions improve reperfusion function when performed later. The data also indicate that Ca²⁺ may enter the myocyte indirectly via activation of the Na⁺/H⁺ and Na⁺/Ca²⁺ exchanger during reperfusion. Inhibition of Na⁺/H⁺ exchange activity by HOE 694 during reperfusion attenuated reperfusion stunning and arrhythmias. Both activation of the Na⁺/H⁺ (and Na⁺/Ca²⁺) exchanger and Ca²⁺ influx via the Ca²⁺ channel could contribute to reperfusion induced Ca²⁺ overload and subsequent injury. The study also showed that altered intracellular Ca²⁺ oscillations play a role in reperfusion stunning and arrhythmias as shown by the use of the SR Ca²⁺ release channel blocker, ryanodine. Inhibition of the sarcoplasmic reticulum Ca²⁺ A TP-ase pump by two novel inhibitors, thapsigargin and cyclopiazonic acid, during ischaemia and early reperfusion improved reperfusion function and reduced the incidence of ventricular arrhythmias. function when unphysiologically high concentrations of the peptide were infused into the heart during reperfusion. Taken together, these data suggest that: 1) Ca²⁺ fluxes during early reperfusion (intracellular and transsarcolemmal) play a role in reperfusion injury, 2) that both the Ca²⁺ channel and Na⁺/H⁺ exchange activity contribute to reperfusion injury by possibly contributing to cytosolic Ca²⁺ overload and that, 3) altered intracellular Ca²⁺ oscillations through the SR play a role in both stunning and arrhythmias. Thus the proposal is that modulation of Ca²⁺ fluxes through either the sarcolemma or the sarcoplasmic reticulum, lessen reperfusion injury (stunning and arrhythmias). Although these data do not provide direct evidence of reperfusion Ca²⁺ overload, they support the concept that calcium ions play a role in the genesis of reversible reperfusion injury.

The sarcoplasmic reticulum (SR) is an intracellular membrane system dedicated to the active regulation of cytosolic calcium in muscle. The opening of Ca²⁺ channels in the SR results in a rapid increase in the myoplasmic Ca²⁺ concentration and the initiation of contraction. Closure of these channels allows the SR to re-accumulate the released Ca²⁺ which results in muscle relaxation. While it is known that a muscle fiber is stimulated to contract by the depolarization of the sarcolemma, it is not understood how this signal is communicated to the SR. The focus of this dissertation is twofold. The first objective is to gain an understanding of the mechanism of Ca²⁺ release from the SR. To this end, three studies have been performed which indicate that Ca²⁺ release is mediated by an oxidation reaction. The second goal is to gain insight into the function of the Ca²⁺ release channel. This is addressed by a fourth study which characterizes the effect of the plant alkaloid, ryanodine on channel operation. The anthraquinones mitoxantrone , doxorubicin, daunorubicin, and rubidazone are shown to be potent stimulators of Ca²⁺ release from SR vesicles. Anthraquinoneinduced Ca²⁺ release is shown to be via a specific interaction with the Ca²⁺ release system of the SR. In addition, a strong interaction between anthraquinone and caffeine binding sites on the Ca²⁺ release channel is observed when monitoring Ca²⁺ fluxes across the SR. It is shown that Ca²⁺ release stimulated by anthraquinones is inhibited by preincubating the quinone with dithionite, a strong reducing agent. Spectrophotometric measurements show that the dithionite treated quinone is in a reduced state. Previous work in this lab has shown that the photooxidizing xanthene dye rose bengal stimulates rapid Ca²⁺ release from skeletal muscle SR vesicles. In this thesis, it is shown that following fusion of vesicles to a bilayer lipid membrane (BLM), Ca²⁺ channel activity is stimulated by nanomolar concentrations of rose bengal in the presence of a broad-spectrum light source. This stimulation is shown to be independent of the Ca²⁺ concentration but is inhibited by μM ruthenium red. The photooxidation of rose bengal is shown to not affect either the K+ or Cl- channels which are present in the SR. Exposure of the Ca²⁺ release channel to 500 nM rose bengal in the presence of light is shown to reverse the modification to the channel induced by μM ryanodine. This apparent displacement of bound ryanodine by nanomolar concentrations of rose bengal is directly observed upon measurement of [³H]ryanodine binding to TSR vesicles. Evidence is presented which suggests that Ca²⁺ release is mediated by singlet oxygen. Micromolar concentrations of the porphyrin meso-Tetra(4-N-methylpyridyl)porphine tetraiodide (TMPyP) is shown to induce the rapid release of Ca²⁺ from skeletal muscle SR vesicles. Porphyrin-induced Ca²⁺ release is stimulated by adenine nucleotides and μM Ca²⁺, and is inhibited by mM Mg²⁺ and μM ruthenium red. High-affinity [³H]ryanodine binding is also enhanced in the presence of the porphyrin. The presence of 1 mM Mg²⁺ in the assay medium sensitizes ryanodine binding to activation by ca²⁺. Porphyrin stimulated single channel activity is also sensitized to activation by Ca²⁺ in the presence of Mg²⁺. Reduction of the porphyrin by dithionite, a strong reducing agent, prior to exposure to the Ca²⁺ release channel inhibited the ability of TMPyP to stimulate Ca²⁺ release. These observations indicate that anthraquinones, rose bengal , and porphyrins induce a stimulation of the Ca²⁺ release protein from skeletal muscle SR by interacting with the ryanodine binding site. In addition, the mechanism of interaction for these compounds appears to be via an oxidation reaction. Nanomolar to micromolar concentrations of ryanodine are shown to alter the gating kinetics of the Ca²⁺ release channel from skeletal muscle SR fused with bilayer lipid membranes. In the presence of asymmetric CsCl, 5 to 40 nM concentrations of ryanodine are shown to activate the channel by increasing the open probability (P₀) without changing the conductance. Statistical analysis of gating kinetics reveal that the open and closed dwell times exhibit bi-exponential distributions that are significantly modified by nM ryanodine. The altered channel gating kinetics seen with low nM ryanodine is reversible and is shown to correlate with the binding kinetics of [³H]ryanodine with its highest affinity site under identical ionic conditions. Ryanodine concentrations between 20 and 50 nM are observed to induce occasional 1/2 conductance fluctuations while ryanodine concentrations greater than 50 nM stabilize the channel into a ½ conductance state which is not reversible. These results are shown to correlate with [³H]ryanodine binding to a second site having lower affinity than the first site. Ryanodine at concentrations greater than 70 μM from the 1/2 to a 1/4 conductance fluctuation , whereas ryanodine concentrations greater than 200 μM cause complete closure of the channel. The concentration of ryanodine required to stabilize either the 1/4 conductance transitions or channel closure do not directly correlate with the measured [³H]ryanodine equilibrium binding constants. However, these results can be explained by considering the association kinetics of ryanodine concentrations greater than 200 nM in the presence of 500 mM CsCl. These results indicate that ryanodine stabilizes four discrete states of the SR release channel and supports the existence of multiple interacting ryanodine binding sites on the channel protein.

Leung, Pan Cheung Catherine. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 105-120). / Abstracts in English and Chinese. / DECLARATION --- p.II / ACKNOWLEDGEMENTS --- p.III / ENGLISH ABSTRACT --- p.IV / CHINESE ABSTRACT --- p.VII / Chapter MODULE 1. --- INTRODUCTION --- p.1 / Chapter 1.1. --- Vascular Endothelium --- p.1 / Chapter 1.1.1. --- Vascular Endothelial Functions --- p.1 / Chapter 1.1.2. --- Calcium Signaling in Vascular Endothelial Cells --- p.2 / Chapter 1.2. --- The Founding Member of TRP Family: Drosophila TRP --- p.3 / Chapter 1.2.1. --- Discovery of Drosophila TRP and TRP-related Proteins --- p.3 / Chapter 1.2.2. --- Drosophila TRPs: Ca2+-permeable Channels? --- p.3 / Chapter 1.3. --- Mammalian TRP Superfamily --- p.5 / Chapter 1.3.1. --- The TRP Subfamily: TRPV --- p.9 / Chapter 1.3.2. --- The TRP Subfamily: TRPM --- p.9 / Chapter 1.3.3. --- The TRP Subfamily: TRPC --- p.11 / Chapter 1.4. --- Functional and Physiological Roles of Mammalian TRPCs --- p.12 / Chapter 1.4.1. --- TRPC1 --- p.15 / Chapter 1.4.2. --- TRPC2 --- p.16 / Chapter 1.4.3. --- "TRPC3, TRPC6 and TRPC7" --- p.17 / Chapter 1.4.4. --- TRPC4 and TRPC5 --- p.19 / Chapter 1.4.5. --- Over-expression of TRPCs: Physiologically Relevant Channels? --- p.20 / Chapter 1.4.6. --- Alternatives to Heterologous Expression Study --- p.21 / Chapter 1.5. --- Aims of the Study --- p.23 / Chapter MODULE 2. --- MATERIALS AND METHODS --- p.24 / Chapter 2.1. --- Functional Characterization of TRPCs by Antisense Technique --- p.24 / Chapter 2.1.1. --- Restriction Enzyme Digestion --- p.26 / Chapter 2.1.2. --- Purification of Released Inserts and Cut pcDNA3 Vectors --- p.27 / Chapter 2.1.3. --- "Ligation of TRPC Genes into Mammalian Vector, pcDNA3" --- p.27 / Chapter 2.1.4. --- Transformation for the Desired Clones --- p.28 / Chapter 2.1.5. --- Plasmid DNA Preparation for Transfection --- p.28 / Chapter 2.1.6. --- Confirmation of the Clones］ --- p.29 / Chapter 2.1.6.1. --- Restriction Enzymes Strategy --- p.29 / Chapter 2.1.6.2. --- Polymerase Chain Reaction (PRC) Check --- p.30 / Chapter 2.1.6.3. --- Automated Sequencing --- p.31 / Chapter 2.2. --- Establishing Stable Cell Lines --- p.33 / Chapter 2.2.1. --- Cell Culture --- p.33 / Chapter 2.2.2. --- Transfection Conditions Optimization --- p.33 / Chapter 2.2.3. --- Geneticin Selection --- p.35 / Chapter 2.3. --- Expression Pattern Studies of TRPC Genes in Vascular Tissues --- p.38 / Chapter 2.3.1. --- Immunofluorescence Staining in Cultured CPAE Cells --- p.38 / Chapter 2.3.2. --- Immunolocalization in Human Cerebral and Coronary Arteries --- p.40 / Chapter 2.3.2.1. --- Paraffin Section Preparation --- p.40 / Chapter 2.3.2.2. --- "Immunohistochemistry for TRPC1, 3, 4 and 6 Channels" --- p.40 / Chapter 2.3.2.3. --- Subcellular Localization of hTRPC1 and hTRPC3 Channels in Endothelial Cells --- p.42 / Chapter 2.4. --- Study of Bradykinin-induced Ca2+ Entry by Calcium Imaging --- p.47 / Chapter 2.4.1. --- Primary Aortic Endothelial Cell Culture --- p.47 / Chapter 2.4.2. --- Fura-2 Measurement of [Ca2+］］］ --- p.47 / Chapter 2.5. --- Study of Functional Role of TRPC6 in Stably Transfected H5V Cells … --- p.49 / Chapter 2.5.1. --- Protein Sample Preparation --- p.49 / Chapter 2.5.2. --- Western Blot Analysis --- p.50 / Chapter 2.5.3. --- Confocal Microscopy for Bradykinin-induced Calcium Entry --- p.51 / Chapter 2.6. --- Data Analysis --- p.52 / Chapter MODULE 3. --- RESULTS --- p.53 / Chapter 3.1. --- Bradykinin-induced Calcium Entry in Vascular Endothelial Cells --- p.53 / Chapter 3.1.1. --- Bradykinin-induced Calcium Entry --- p.53 / Chapter 3.1.2. --- Effects of cGMP and PKG on Bradykinin-induced Ca2+ Entry --- p.54 / Chapter 3.1.3. --- Effects of HOEUO on Bradykinin-induced Store-independent Ca2+ Entry --- p.55 / Chapter 3.1.4. --- Involvement of Phospholipase C Pathway in Bradykinin-induced Store-independent Ca2+ Entry --- p.55 / Chapter 3.2. --- Expression Pattern of TRPC Channels in Vascular Systems --- p.63 / Chapter 3.2.1. --- Immunolocalization of TRPC Homologues in CPAE Cells --- p.63 / Chapter 3.2.2. --- Immunolocalization of TRPC Homologues in Human Cerebral and Coronary Arteries --- p.66 / Chapter 3.2.3. --- Subcellular Localization of TRPC1 and TRPC3 Fused to Enhanced Green Fluorescence Protein (EGFP) --- p.77 / Chapter 3.3. --- Functional Role of TRPC6 Channels in Bradykinin-induced Calcium Entry --- p.81 / Chapter 3.3.1. --- Effect of Antisense TRPC6 Construct on Protein Expression --- p.81 / Chapter 3.3.2. --- Effect of Antisense TRPC6 on Bradykinin-induced Ca2+ Entry --- p.81 / Chapter 3.3.3. --- Effect of Antisense TRPC6 on Thapsigargin-depleted Ca2+ Stores --- p.82 / Chapter MODULE 4. --- DISCUSSION --- p.89 / Chapter 4.1. --- Characterization of Bradykinin-induced Ca2+ Entry in Endothelial Cells --- p.89 / Chapter 4.2. --- The Expression Pattern of TRPC Isoforms in Vascular Tissues --- p.93 / Chapter 4.3. --- Functional Characterization of TRPC6 Homologues in Bradykinin-induced Ca2+ Entry --- p.98 / Chapter 4.4. --- Perspectives --- p.103 / Chapter 4.5. --- Conclusion --- p.104 / Chapter MODULE 5. --- REFERENCES --- p.105

Cyclic nucleotide-gated (CNG) ion channels are Ca2+ permeable nonselective cation channels that are directly gated by binding of cAMP or cGMP, thus providing a linkage between two important signal molecules, cyclic nucleotides and calcium. They are known to play an important role in sensory transduction and in second-messenger modulation of synaptic neurotransmitter release. Previous studies showed that besides in neuronal cells, CNG were found also in non-neuronal tissues including heart, kidney, blood vessels and spleen, they are reported to be involved in a variety of cell function. / Ion channels play an indispensable role in endothelial cells, which is a unique signal-transducting surface in the vascular system that is responsible in altering vascular tone. The present study investigated the expression and functional roles of the cyclic nucleotide gated channels (CNG) in regulating the intracellular calcium level of vascular endothelial cells using molecular and calcium measurement techniques. / The present study provided evidence that the CNG channels, especially that of CNGA2, were expressed in vascular tissues. I used a variety of different methods, including RT-PCR, northern blot, in-situ hybridization, immunohistochemistry and western blot to study the localization of CNGA2 channels. RT-PCR amplify a CNGA2 fragment of 582bp from RNAs isolated from bovine vascular endothelial cell line, rat vascular smooth muscle cell line and rat aorta. Northern blot analysis detected a 2.3-kilobase (kb) CNGA2 transcript in rat aorta mRNA. The cellular distribution of CNGA2 was further studied by in-situ hybridization, which demonstrated expression of CNGA2 mRNA in human vascular endothelial and vascular smooth muscle cells. Immunohistochemistry data also agreed with those generated from in-situ hybridization. Western blot data also demonstrated proteins of CNG2 was expressed in both human vascular endothelial cells and vascular smooth cells layer. Subcellular localization of CNGA2 inside the vascular endothelial cells was also investigated with the use of a GFP linked CNGA2 channel gene. Taken together, the results showed that CNGA2 proteins were expressed on the plasma membrane of the vascular endothelial cells. (Abstract shortened by UMI.) / Cheng Kwong Tai Oscar. / "July 2005." / Adviser: Xiaoqiang Yao. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3531. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 216-243). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.