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- Title
Regulation of ATP-sensitive K+ channels by caveolin-enriched microdomains in cardiac myocytes.
- Authors
Vivek Garg; Jundong Jiao; Keli Hu
- Abstract
Aims ATP-sensitive potassium (KATP) channels in the heart are critical regulators of cellular excitability and action potentials during ischaemia. However, little is known about subcellular localization of these channels and their regulation. The present study was designed to explore the potential role of caveolae in the regulation of KATP channels in cardiac ventricular myocytes. Methods and results Both adult and neonatal rat cardiomyocytes were used. Subcellular fractionation by density gradient centrifugation, western blotting, co-immunoprecipitation, and immunofluorescence confocal microscopy were employed in combination with whole-cell voltage clamp recordings and siRNA gene silencing. We detected that the majority of KATP channels on the plasma membrane of cardiac myocytes were localized in caveolin-3-enriched microdomains by cell fractionation and ultracentrifugation followed by western blotting. Immunofluorescence confocal microscopy revealed extensive colocalization of KATP channel pore-forming subunit Kir6.2 and caveolin-3 along the plasma membrane. Co-immunoprecipitation of cardiac myocytes showed significant association of Kir6.2, adenosine A1 receptors, and caveolin-3. Furthermore, whole-cell voltage clamp studies suggested that adenosine A1 receptor-mediated activation of KATP channels was largely eliminated by disrupting caveolae with methyl-β-cyclodextrin or by small interfering RNA, whereas pinacidil-induced KATP activation was not altered. Conclusion We demonstrate that KATP channels are localized to caveolin-enriched microdomains. This microdomain association is essential for adenosine receptor-mediated regulation of KATP channels in cardiac myocytes.
- Publication
Cardiovascular Research, 2009, Vol 82, Issue 1, p51
- ISSN
0008-6363
- Publication type
Academic Journal
- DOI
10.1093/cvr/cvp039