1993 |
Mutafova-Yambolieva, Violeta N. |
F05Activity Code Description: To provide collaborative research opportunities for qualified non-immigrant alien scientists who hold a doctoral degree or its equivalent in one of the biomedical or behavioral sciences. |
Peptidergic Modulation of Sympathetic Co-Transmission @ University of Nevada Reno |
0.958 |
1994 |
Mutafova-Yambolieva, Violeta N. |
F05Activity Code Description: To provide collaborative research opportunities for qualified non-immigrant alien scientists who hold a doctoral degree or its equivalent in one of the biomedical or behavioral sciences. |
Peptidergic Modulation of Sympathetic Cotransmission @ University of Nevada Reno
The proposed research during the fellowship will provide me with vital experience of sympathetic nervous system activity studies. Thus, my main goals for this period are: (i) To study the modulating effects of cardiovascular peptides ET, ANP, and BNP on the pre- and postsynaptic mechanisms of peripheral sympathetic cotransmission at the levels of isolated tissues in vitro and of an organism devoided of central reflexes in vivo as well as to study the participation of the endothelium, the EDRF/NO, cGMP, IP3, and Ca++ in these effects; (ii) To learn the basic techniques necessary for studies on peripheral sympathetic cotransmission, particularly those related to a) transmitter (ATP and NE) release measurement, b) contractile responses in isolated blood vessels, c) intracellular Ca++ and cyclic nucleotide signaling and d) hemodynamics of pitched animals (see Item 21, Research plan). Professor Westfall's laboratory is an ideal place to study the role of endogenous peptides on sympathetic neurotransmission. Professor David Westfall and his group have played a fundamental role in developing the concept that sympathetic neurotransmission involves the release of the cotransmitters ATP and NE. In addition his group has recently developed the concept that prejunctional purinoceptors, which modulate neurotransmitter release, may exist as several subtype. The laboratory is also well known for its ability to develop new methodologies to apply to issues of neurotransmission. For example, his laboratory is one of the few in the world where the release of ATP and NE can be simultaneously evaluated. The opportunity to learn and work in such an environment particularly in a place where the research interests are so congruent with my own, will no doubt enhance the development of my scientific career.
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0.958 |
1999 — 2007 |
Mutafova-Yambolieva, Violeta N. |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Neuromuscular Transmission in Arteries and Veins @ University of Nevada Reno
DESCRIPTION: (adapted from the applicant's abstract) The long range objective of the research outlined in this proposal is to characterize neural control mechanisms of resistance and capacitance blood vessels of the splanchnic circulation and determine mechanisms which underlie differential regulation of these two vascular networks. The proposed studies will compare sympathetic co-transmission in guinea pig mesenteric artery and vein. The PI hypothesizes that responses to nerve stimulation in vein and artery differ because: (1) the mechanisms which are initiated by ATP and norepinephrine (NE) in smooth muscle differ and/or (2) the amount and/or ratio of ATP and NE at the vicinity of the postjunctional receptor differ. Specific Aims 1 and 2 will address the first part of this hypothesis by characterizing the effects of exogenous and endogenous NE and ATP on membrane potential (intracellular microelectrode techniques) and force development (organ bath experiments) in artery and vein and determining whether different subtypes of P2 purinergic and alpha-adrenergic receptors are involved. Specific Aim 3 will address the second part of this hypothesis by employing state-of-the-art techniques to simultaneously measure nerve evoked outflow of ATP (HPLC-fluorscence detection) and NE (HPLC- electrochemical detection) in artery and vein. Thus, mesenteric artery and vein will be uniquely compared in terms of both transmitter release and postjuctional effector mechanisms. These studies will provide new insights into the differential control of arteries and veins by nerves. They will also aid in clarifying the role of ATP as a neurotransmitter in the splanchnic circulation and its relationship to NE as the primary sympathetic neurotransmitter.
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0.958 |
2009 — 2013 |
Mutafova-Yambolieva, Violeta |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Novel Mechanisms in Enteric Inhibitory Neuretransmission @ University of Nevada Reno
A number of motility disorders are believed to be caused by defects in the neural control of the gastrointestinal (GI) tract. However, the underlying pathophysiology remains largely undefined and often the treatment is ineffectively targeted. Our long-term goal is to develop methods for the prevention and treatment of conditions qualified as "neuropathies" based on understanding of the inhibitory purinergic signaling in the gut. The central hypothesis of this proposal is that beta-nicotinamide adenine dinucleotide ((3-NAD) is a novel inhibitory neurotransmitter in the GI tract. Particularly, we hypothesize that (3-NAD is stored in synaptic vesicles, is released upon action potential firing, activates P2Y purinergic receptors and apamin-sensitive small conductance Ca2+-activated potassium (SK) channels on either interstitial cells of Cajal (ICC), smooth muscle cells (SMC) or fibroblast-like cells (FLC), causes membrane hyperpolarization and smooth muscle relaxation, and is removed by CD38- and CD157-mediated metabolism and by uptake in nerve varicosities. The work, carried out with colon preparations from humans, non-human primates, and mice, will: (i) determine the cell types that are the primary source of release of (3-NAD and ATP during EPS of enteric nerves (Aim 1), (ii) examine whether the expression, distribution, and function of vesicular nucleotide transporter (VNUT) is consistent with the role of (3-NAD as an inhibitory motor neurotransmitter in GI muscles (Aim 2), (iii) determine the primary postjunctional targets of PNAD action (Aim 3), and (iv) examine the major mechanisms of removal of (3-NAD (i.e., enzymatic degradation or neuronal uptake), and hence of terminating its neurotransmitter actions (Aim 4). We will examine overflow of purine neurotransmitters and their metabolites using high performance liquid chromatography (HPLC) techniques along with immunohistochemistry, protein biochemistry, molecular biology techniques, electron microscopy, flow cystometry analysis, electrophysiology, and functional approaches to better understand the role of p-NAD and other purines as putative neurotransmitters. This research has the potential to fundamentally advance our understanding of enteric purinergic signaling, and could have important implications for developing novel therapeutic strategies for GI motility disorders based on defects of neural control of the GI muscles.
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1 |
2014 — 2018 |
Mutafova-Yambolieva, Violeta N. |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Novel Mechanisms of Enteric Purinergic Signaling @ University of Nevada Reno
A number of GI symptoms and motility disorders, including idiopathic inflammatory bowel diseases (IBD), are linked, directly or indirectly, to defects in the neural control of the GI system. Neurogenic purines are central to gut motility by providing tonic inhibition in the colon and by influencing gut contractility and propulsion motility. In recent years we have determined that NAD+ and ADP-ribose, but not ATP, fulfill presynaptic and postsynaptic criteria for a motor inhibitory neurotransmitter in the colon. This project will build upon our findings and will pursue the mechanisms of release, metabolism and action of extracellular purines and metabolites with the goal to greatly improve our understanding of key mechanisms of purinergic signaling in the human gut. In Aim 1 we will investigate key mechanisms of extracellular metabolism of ATP, NAD+ and ADPR, intersecting pathways, and regional prevalence of purinergic metabolic pathways in the large intestine. In Aim 2 we will investigate the complexities of purinergic regulation in the colon and the postjunctional activities of purines and metabolites on muscle contractility and motility. In particular, we will investigate the involvment of P2X7 receptors and small conductance Ca2+-activated K-t- (SK) channels in PDGFRa+ cells in mediating responses to ATP and will examine purine-mediated Ca2+ desensitization mechanisms in colonic smooth muscle. In Aim 3 we will investigate how neuronal release, degradation and action of extracellular purine nucleotides and metabolites are affected in colitis. We will conduct our studies on colons from human and non-human primates, in mice with specific gene deletions, in reporter strains of mice with constitutive expression of green fluorescence proteins, and in animal models of colitis. We will examine constitutive and evoked overflow and extracellular biotransformation of purines using enhanced high performance liquid chromatography techniques along with immunohistochemistry, protein biochemistry, fluorescence-activated cell sorting, electrophysiology, and functional approaches to better understand mechanisms of purinergic signaling in the gut. This research has the potential to advance new concepts in regulatory purine-mediated mechanisms in the distal GI tract.
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0.958 |
2020 — 2021 |
Mutafova-Yambolieva, Violeta N. |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Urothelial Purinergic Signaling During Bladder Filling @ University of Nevada Reno
PROJECT SUMMARY/ABSTRACT The bladder must refrain from premature contraction during filling and empty when critical intravesical volume and pressure are reached. Abnormal continence or voiding of urine are frequently associated with abnormal excitability of the detrusor smooth muscle (DSM) in the course of bladder filling. Current therapies are largely ineffective and frequently have intolerable side effects. There is a pressing need to better understand the fundamental mechanisms of regulation of bladder function during filling that may yield novel ideas for more efficient control of bladder excitability. Excitatory purines that increase DSM contractility (e.g., ATP and ADP) and inhibitory purines that decrease DSM contractility (e.g., NAD, ADP-ribose, AMP and adenosine) are released from the urothelium and form ?a regulatory purine pool? deep in the bladder wall. The relative composition of this pool (e.g., inhibitory vs. excitatory) might be changing during bladder filling to enable adequate DSM excitability. However, purine-mediated local mechanisms of signaling between the urothelium and DSM during filling are not understood. This project will investigate 1) several mechanisms - release, metabolism and transurothelial transport - that determine the type and relative amount of purine mediators available in suburothelium (SubU)/lamina propria (LP) during filling and 2) influences of extracellular purines on non-neural types of cells in the bladder wall that regulate DSM excitability. Specific Aim 1 will test the hypothesis that asymmetrical availability of purines leads to a higher ratio of inhibitory/excitatory purines in SubU/LP during the storage phase of bladder filling whereas reduction of this ratio at high volume and pressure facilitates micturition. ATP, ADP, NAD, ADP-ribose, AMP and adenosine will be examined simultaneously in SubU/LP and in lumen during filling. Specific Aim 2 will test the hypothesis that metabolism and transurothelial transport of purines regulate adequate purine availability in the SubU/LP during bladder filling. Specific Aim 3 will test the hypothesis that urothelial purines contribute to the intrinsic control of bladder excitability during filling by affecting urothelial cells, submucosal PDGFR?+ cells and DSM cells. To obtain direct access to SubU/LP, we will use a decentralized (ex vivo) bladder model with DSM removed and we will perform in vivo and ex vivo microdialysis of the bladder wall. We will use analytical chemistry, electrophysiology, molecular biology, protein biochemistry, and functional and Ca2+ imaging methodologies, including expression of optogenetic sensors in selected cell types in the bladder wall. Studies will employ transgenic mice such as Pdgfr?egfp/+, smMHC-GCaMP6f, PDGFR?-GCaMP6, Trpv4eGFP, AQP3-GCaMP6m mice and mice with specific gene deletions. Key mechanisms will be validated in bladders from Cynomolgus monkeys (Macaca fascicularis) to determine how knowledge obtained in mouse bladder translates to the primate bladder. At the end of the project period, we will understand the biological significance of urothelial purinergic signaling for mechanosensitive connectivity between the urothelium and DSM and we may identify novel mechanistic targets for the treatment of anomalous bladder excitability.
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0.958 |