verbatim): ATP-sensitive (KATP) channels couple energy metabolism and stress to membrane excitability and are highly expressed in heart. Their function in the heart and coronary vasculature has been studied extensively by the use of pharmacological agents that open or block KATP channels. The molecular cloning of subunits of KATP channel revealed that KATP channels consist of pore-forming Kir6 subunits in association with regulatory SUR subunits. There are two Kir6 members (Kir6.1 and Kir6.2) - both are highly expressed in heart. Cardiac KATP channels are believed to consist of Kir6.2/SUR2 complexes. However, the role of Kir6.1 is unknown. The overall goal of this application is to examine the function of Kir6.1 subunits in the cardiovascular system. Since the localization of a protein can be indicative of its function, we will examine the regional, cellular and subcellular distribution patterns of Kir6.1 subunits in cardiac myocytes, the conduction system, in the coronary vasculature and in endothelial cells using immunohistochemistry techniques (we have developed excellent antibodies for this purpose). We show biochemically and electrophysiologically that Kir6.1 and Kir6.2 subunits can co-assemble in heterologous expression systems, suggesting that this may also occur in heart. We will examine whether such co-assembly takes place for native Kir6 proteins. We will also investigate the functional characteristics of heteromeric Kir6 channels using patch clamp techniques. We will generate mice with targeted disruption of the Kir6.1 gene. LoxP sites will be introduced in the Kir6.1 locus and these mice will be crossed with others overexpressing Cre in the heart. We will utilize these mice directly to examine the role of Kir6.1 subunits in the function of heart and vasculature using isolated, Langendorff-perfused heart techniques. Coronary blood flow and -reserve will be measured along with heart function during ischemia, reperfusion and ischemic preconditioning. These studies will provide a framework in which to understand the complexity of KATP channels in the cardiovascular system, in particular the role of Kir6.1 subunits, and will provide molecular insights into the function of KATP channels in animals during normal and pathophysiological conditions.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL064838-03
Application #
6637526
Study Section
Cardiovascular and Pulmonary Research A Study Section (CVA)
Program Officer
Wang, Lan-Hsiang
Project Start
2001-05-01
Project End
2005-02-28
Budget Start
2003-03-01
Budget End
2004-02-29
Support Year
3
Fiscal Year
2003
Total Cost
$412,500
Indirect Cost
Name
New York University
Department
Pediatrics
Type
Schools of Medicine
DUNS #
121911077
City
New York
State
NY
Country
United States
Zip Code
10016
Yoshida, Hidetada; Bao, Li; Kefaloyianni, Eirini et al. (2012) AMP-activated protein kinase connects cellular energy metabolism to KATP channel function. J Mol Cell Cardiol 52:410-8
Bao, Li; Hadjiolova, Krassimira; Coetzee, William A et al. (2011) Endosomal KATP channels as a reservoir after myocardial ischemia: a role for SUR2 subunits. Am J Physiol Heart Circ Physiol 300:H262-70
Nakamura, Tomoe Y; Coetzee, William A (2008) Functional and pharmacological characterization of a Shal-related K+ channel subunit in Zebrafish. BMC Physiol 8:2
Kang, Guoxin; Leech, Colin A; Chepurny, Oleg G et al. (2008) Role of the cAMP sensor Epac as a determinant of KATP channel ATP sensitivity in human pancreatic beta-cells and rat INS-1 cells. J Physiol 586:1307-19
Liu, Gong Xin; Vepa, Sanjay; Artman, Michael et al. (2007) Modulation of human cardiovascular outward rectifying chloride channel by intra- and extracellular ATP. Am J Physiol Heart Circ Physiol 293:H3471-9
Malester, Brian; Tong, Xiaoyong; Ghiu, Ioana et al. (2007) Transgenic expression of a dominant negative K(ATP) channel subunit in the mouse endothelium: effects on coronary flow and endothelin-1 secretion. FASEB J 21:2162-72
Harrell, M D; Harbi, S; Hoffman, J F et al. (2007) Large-scale analysis of ion channel gene expression in the mouse heart during perinatal development. Physiol Genomics 28:273-83
Tong, XiaoYong; Porter, Lisa M; Liu, GongXin et al. (2006) Consequences of cardiac myocyte-specific ablation of KATP channels in transgenic mice expressing dominant negative Kir6 subunits. Am J Physiol Heart Circ Physiol 291:H543-51
Kang, Guoxin; Chepurny, Oleg G; Malester, Brian et al. (2006) cAMP sensor Epac as a determinant of ATP-sensitive potassium channel activity in human pancreatic beta cells and rat INS-1 cells. J Physiol 573:595-609
Dhar-Chowdhury, Piyali; Harrell, Maddison D; Han, Sandra Y et al. (2005) The glycolytic enzymes, glyceraldehyde-3-phosphate dehydrogenase, triose-phosphate isomerase, and pyruvate kinase are components of the K(ATP) channel macromolecular complex and regulate its function. J Biol Chem 280:38464-70

Showing the most recent 10 out of 13 publications