The heart represents a primary target of hypoxia-induced morphological and physiological alterations. Major alterations in cardiac gap junctions have been demonstrated following acute ischemic events, including decreased function and expression in damaged cells as well as reorganization of Cx43 distribution in the cardiac muscle cells as the tissue remodels. Moreover, expression of gap junctions between injured myocytes appears to be deleterious following ischemic injury, allowing spread of cell death from the injured cell to coupled neighbors (a phenomenon termed """"""""bystander cell death""""""""); nonjunctional hemichannel opening may also contribute to this cell death. The general hypotheses to be tested in this proposal are that gap junctions formed by Cx43 are both targets and mediators of hypoxia-induced cardiac injury. The studies that are explicitly proposed for this Project will specifically study effects on cardiac gap junctions of two components of ischemia: hypoxia and hypercapnia. We will test three hypotheses: a) that hypoxia and hypercapnia may affect developing cardiac gap junctions through altered expression of Cx43 and its associated proteins or altered affinity of Cx43 for its binding partners, b) that hypoxia and hypercapnia will produce functional changes in gap junctions or hemichannels, and c) that gap junctions in developing heart can spread cell injury that is enhanced under stressful conditions. These hypotheses are formulated primarily on the basis of our previous studies of responses of gap junctions to related stimuli, substantiated in some cases by preliminary data obtained using cardiac tissue from animals maintained for 1-2 weeks in the hypoxia chambers. We expect that these studies will provide new information regarding effects on gap junctions of ischemia-related stresses. In addition, we will both benefit from and contribute broadly to the other Projects in the Program, due to our interest in gap junctions in brain and kidney and in the basic mechanisms of cellular pH regulation.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Program Projects (P01)
Project #
5P01HD032573-12
Application #
7312369
Study Section
Special Emphasis Panel (ZHD1)
Project Start
Project End
Budget Start
2006-08-01
Budget End
2007-07-31
Support Year
12
Fiscal Year
2006
Total Cost
$173,887
Indirect Cost
Name
University of California San Diego
Department
Type
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
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Yao, Hang; Azad, Priti; Zhao, Huiwen W et al. (2016) The Na+/HCO3- co-transporter is protective during ischemia in astrocytes. Neuroscience 339:329-337
Jha, Aashish R; Zhou, Dan; Brown, Christopher D et al. (2016) Shared Genetic Signals of Hypoxia Adaptation in Drosophila and in High-Altitude Human Populations. Mol Biol Evol 33:501-17
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Gu, Xiang Q; Pamenter, Matthew E; Siemen, Detlef et al. (2014) Mitochondrial but not plasmalemmal BK channels are hypoxia-sensitive in human glioma. Glia 62:504-13
Gersten, Merril; Zhou, Dan; Azad, Priti et al. (2014) Wnt pathway activation increases hypoxia tolerance during development. PLoS One 9:e103292
Udpa, Nitin; Ronen, Roy; Zhou, Dan et al. (2014) Whole genome sequencing of Ethiopian highlanders reveals conserved hypoxia tolerance genes. Genome Biol 15:R36
Salameh, Ahlam Ibrahim; Ruffin, Vernon A; Boron, Walter F (2014) Effects of metabolic acidosis on intracellular pH responses in multiple cell types. Am J Physiol Regul Integr Comp Physiol 307:R1413-27
Douglas, Robert M; Chen, Alice H; Iniguez, Alejandra et al. (2013) Chemokine receptor-like 2 is involved in ischemic brain injury. J Exp Stroke Transl Med 6:1-6
Parker, Mark D; Boron, Walter F (2013) The divergence, actions, roles, and relatives of sodium-coupled bicarbonate transporters. Physiol Rev 93:803-959

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