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RECEPTORS AND SIGNAL TRANSDUCTION

H₂S preconditioning-induced PKC activation regulates intracellular calcium handling in rat cardiomyocytes

Cardiovascular Biology Research Group, Department of Pharmacology, National University of Singapore, Singapore

Submitted 7 August 2007 ; accepted in final form 15 November 2007

The present study was aimed to investigate the regulatory effect of protein kinase C (PKC) on intracellular Ca²⁺ handling in hydrogen sulfide (H₂S)-preconditioned cardiomyocytes and its consequent effects on ischemia challenge. Immunoblot analysis was used to assess PKC isoform translocation in the rat cardiomyocytes 20 h after NaHS (an H₂S donor, 10^–4 M) preconditioning (SP, 30 min). Intracellular Ca²⁺ was measured with a spectrofluorometric method using fura-2 ratio as an indicator. Cell length was compared before and after ischemia-reperfusion insults to indicate the extent of hypercontracture. SP motivated translocation of PKC, PKC, and PKC to membrane fraction but only translocation of PKC and PKC was abolished by an ATP-sensitive potassium channel blocker glibenclamide. It was also found that SP significantly accelerated the decay of both electrically and caffeine-induced intracellular [Ca²⁺] transients, which were reversed by a selective PKC inhibitor chelerythrine. These data suggest that SP facilitated Ca²⁺ removal via both accelerating uptake of Ca²⁺ into sarcoplasmic reticulum and enhancing Ca²⁺ extrusion through Na⁺/Ca²⁺ exchanger in a PKC-dependent manner. Furthermore, blockade of PKC also attenuated the protective effects of SP against Ca²⁺ overload during ischemia and against myocyte hypercontracture at the onset of reperfusion. We demonstrate for the first time that SP activates PKC, PKC, and PKC in cardiomyocytes via different signaling mechanisms. Such PKC activation, in turn, protects the heart against ischemia-reperfusion insults at least partly by ameliorating intracellular Ca²⁺ handling.

protein kinase C isoforms; ischemia and reperfusion; cardioprotection; ATP-sensitive potassium channel

This article has been cited by other articles:

				Q. C. Yong, S. W. Lee, C. S. Foo, K. L. Neo, X. Chen, and J.-S. Bian Endogenous hydrogen sulphide mediates the cardioprotection induced by ischemic postconditioning Am J Physiol Heart Circ Physiol, September 1, 2008; 295(3): H1330 - H1340. [Abstract] [Full Text] [PDF]