In this renewal we propose to establish a more mechanistic basis for the roles of the connexins in cell-cell communication in the microvasculature. We will study radial and longitudinal cell-cell communication in the arterioles, emphasizing the idea that the smooth muscle and the endothelial cell are united to form a functional unit via the myoendothelial cell junctions. The application takes advantage of our extensive theoretical and technical developments in the use of calcium and voltage imaging on in vitro and in vivo systems. We will systematically test the idea the linkage of the calcium pools of the smooth muscle and the endothelium confers unique response patterns on the behavior of arterioles. A unique aspect of this proposal is a comparative study of the arterioles from three species known to have quite different arteriolar responses. Using the tools of molecular genetics we have also begun the process of the process of identification of specific molecular contributors to gap junctional communication. We will include experiments on connexin 37 and 40 knockouts and newly developed smooth muscle and endothelial-cell specific knockouts of connexin 43. We seek to answer three broad questions. First, How does cell-cell coupling between smooth muscle and endothelial cell modulate arteriolar reactivity? Second, what are the intercellular pathways that are involved in the conducted vasomotor response? Third, is gap junctional communication physiologically important? Several interrelated hypotheses will be tested. These are: Hypothesis 1 - Myoendothelial coupling of both membrane potential and calcium pools play a critical role in determining local responses to stimulation Hypothesis 2 - Myoendothelial coupling of changes in membrane potential and not changes in the endothelial cell calcium mediate the conducted vasomotor responses Hypothesis 3 - Similar pathways for cell-cell coupling exist in vitro and in vivo Hypothesis 4 - The endothelium functions as a preferential pathway for dye and electrical coupling. Hypothesis 5 - Intercellular communication is mediated by multiple connexins Hypothesis 6- Gap junctional communication plays a role in the establishment of normal vasomotor tone

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL053318-07
Application #
6526736
Study Section
Experimental Cardiovascular Sciences Study Section (ECS)
Program Officer
Goldman, Stephen
Project Start
1995-01-01
Project End
2005-07-31
Budget Start
2002-08-01
Budget End
2003-07-31
Support Year
7
Fiscal Year
2002
Total Cost
$346,000
Indirect Cost
Name
University of Virginia
Department
Physiology
Type
Schools of Medicine
DUNS #
001910777
City
Charlottesville
State
VA
Country
United States
Zip Code
22904
Koval, Michael; Billaud, Marie; Straub, Adam C et al. (2011) Spontaneous lung dysfunction and fibrosis in mice lacking connexin 40 and endothelial cell connexin 43. Am J Pathol 178:2536-46
Figueroa, Xavier F; Duling, Brian R (2009) Gap junctions in the control of vascular function. Antioxid Redox Signal 11:251-66
Veliz, Loreto P; Gonzalez, Francisco G; Duling, Brian R et al. (2008) Functional role of gap junctions in cytokine-induced leukocyte adhesion to endothelium in vivo. Am J Physiol Heart Circ Physiol 295:H1056-H1066
Figueroa, Xavier F; Duling, Brian R (2008) Dissection of two Cx37-independent conducted vasodilator mechanisms by deletion of Cx40: electrotonic versus regenerative conduction. Am J Physiol Heart Circ Physiol 295:H2001-7
Isakson, Brant E; Best, Angela K; Duling, Brian R (2008) Incidence of protein on actin bridges between endothelium and smooth muscle in arterioles demonstrates heterogeneous connexin expression and phosphorylation. Am J Physiol Heart Circ Physiol 294:H2898-904
Isakson, Brant E; Ramos, Susan I; Duling, Brian R (2007) Ca2+ and inositol 1,4,5-trisphosphate-mediated signaling across the myoendothelial junction. Circ Res 100:246-54
Figueroa, Xavier F; Chen, Chien-Chang; Campbell, Kevin P et al. (2007) Are voltage-dependent ion channels involved in the endothelial cell control of vasomotor tone? Am J Physiol Heart Circ Physiol 293:H1371-83
Liao, Yongbo; Regan, Christopher P; Manabe, Ichiro et al. (2007) Smooth muscle-targeted knockout of connexin43 enhances neointimal formation in response to vascular injury. Arterioscler Thromb Vasc Biol 27:1037-42
Isakson, Brant E; Damon, David N; Day, Kathleen H et al. (2006) Connexin40 and connexin43 in mouse aortic endothelium: evidence for coordinated regulation. Am J Physiol Heart Circ Physiol 290:H1199-205
Isakson, Brant E; Duling, Brian R (2005) Heterocellular contact at the myoendothelial junction influences gap junction organization. Circ Res 97:44-51

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