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cGMP/PKG pathway mediates myocardial postconditioning protection in rat hearts by delaying normalization of intracellular acidosis during reperfusion.
MedLine Citation:
PMID:  21362429     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Ischemic postconditioning has been demonstrated to limit infarct size in patients, but its molecular mechanisms remain incompletely understood. Low intracellular pH (pHi) inhibits mitochondrial permeability transition, calpain activation and hypercontracture. Recently, delayed normalization of pHi during reperfusion has been shown to play an important role in postconditioning protection, but its relation with intracellular protective signaling cascades is unknown. The present study investigates the relation between the rate of pHi normalization and the cGMP/PKG pathway in postconditioned myocardium. In isolated Sprague-Dawley rat hearts submitted to transient ischemia both, postconditioning and acidic reperfusion protocols resulted in a similar delay in pHi recovery measured by (31)P-NMR spectroscopy (3.6±0.2min and 3.5±0.2min respectively vs. 1.4±0.2min in control group, P<0.01) and caused equivalent cardioprotection (48% and 41% of infarct reduction respectively, P<0.01), but only postconditioning increased myocardial cGMP levels (P=0.02) and activated PKG. Blockade of cGMP/PKG pathway by the addition of the guanylyl cyclase inhibitor ODQ or the PKG inhibitor KT5823 during reperfusion accelerated pHi recovery and abolished cardioprotection in postconditioned hearts, but had no effect in hearts subjected to acidic reperfusion suggesting that PKG signaling was upstream of delayed pHi normalization in postconditioned hearts. In isolated cardiomyocytes the cGMP analog 8-pCPT-cGMP delayed Na(+)/H(+)-exchange mediated pHi normalization after acidification induced by a NH(4)Cl pulse. These results demonstrate that the cGMP/PKG pathway contributes to postconditioning protection at least in part by delaying normalization of pHi during reperfusion, probably via PKG-dependent inhibition of Na(+)/H(+)-exchanger.
Authors:
Javier Inserte; Ignasi Barba; Marcos Poncelas-Nozal; Victor Hernando; Luís Agulló; Marisol Ruiz-Meana; David Garcia-Dorado
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-2-26
Journal Detail:
Title:  Journal of molecular and cellular cardiology     Volume:  -     ISSN:  1095-8584     ISO Abbreviation:  -     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-3-2     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0262322     Medline TA:  J Mol Cell Cardiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2010. Published by Elsevier Ltd.
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