Inhibition of the nitric oxide/cyclic guanosine monophosphate pathway limited the cardioprotective effect of post-conditioning in hearts with apical myocardial infarction.
Reperfusion damage involves opening of the mitochondrial permeability transition pore (mPTP) and loss of ATP synthesis. Several cardioprotective pathways are activated by ischemic or pharmacological post-conditioning (PC). The mechanisms that are activated by PC in no co-morbidity murine models include: activation of rescue kinases, oxidative stress reduction, glycolytic flux regulation and preservation of ATP synthesis. However, relatively scarce efforts have been made to define whether the efficacy of PC signaling is blunted by risk factors or systemic diseases associated with ischemic heart pathology. Experimental evidence has shown that the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling is a main mechanism activated by PC in hearts without pathological history. In this work we evaluated the participation of the NO pathway, through downstream kinase activation and inhibition of mPTP in hearts with previous infarct. Myocardial infarction was induced with a single dose of isoproterenol (85 mg/kg i.p.) to male Wistar rats. After 24 h, the hearts were mounted into the Langendorff system and subjected to 30 min of ischemia and 60 min of reperfusion. PC consisted of 5 cycles of 30 s of reperfusion/30 s of ischemia, then the hearts were reperfused with or without inhibitors of the NO/cGMP pathway. PC activates the NO/cGMP pathway, as increased cGMP and NO levels were detected in isoproterenol-treated hearts. The cardioprotective effect of PC was abolished with both L-NAME (inhibitor of constitutive NO synthase) and ODQ (inhibitor of soluble guanylate cyclase), whereas the NO donor (DETA-NO) restored cardioprotection even in the presence of L-NAME or ODQ. We also found that mitochondrial structure and function was preserved in PC hearts. We conclude that PC exerts cardioprotection in hearts with previous infarct by maintaining mitochondrial structure and function through NO-dependent pathway.
['Correa|Francisco|F|', 'Buelna-Chontal|Mabel|M|', 'Chagoya|Victoria|V|', 'García-Rivas|Gerardo|G|', 'Vigueras|Rosa María|RM|', 'Pedraza-Chaverri|José|J|', 'García-Niño|Wylly Ramsés|WR|', 'Hernández-Pando|Rogelio|R|', 'León-Contreras|Juan Carlos|JC|', 'Zazueta|Cecilia|C|']
D000818:Animals D006157:Guanosine Monophosphate D057775:Ischemic Postconditioning D008297:Male D008929:Mitochondria, Heart D009203:Myocardial Infarction D015428:Myocardial Reperfusion Injury D019331:NG-Nitroarginine Methyl Ester D009569:Nitric Oxide D051381:Rats D017208:Rats, Wistar D015398:Signal Transduction
Post-conditioning cGMP Isoproterenol Reperfusion injury