Exercise preconditioning provides early cardioprotection against exhaustive exercise in rats: Potential involvement of protein kinase C delta translocation

摘要

The objective of this study was to investigate the early cardioprotective effect of exercise preconditioning (EP) on the exhaustive exercise-induced myocardial injury in rats and the role of protein kinase C delta isoform (PKCd) in EP. Rats were subjected to run on the treadmill for four periods of 10 min each at 30 m/min with intervening periods of rest of 10 min as an EP protocol. The exhaustive exercise was performed 0.5 h after EP. PKC inhibitor chelerythrine (CHE) was injected before EP. Our results showed that EP markedly attenuated the exhaustive exercise-induced myocardial ischemia/hypoxia, ultrastructural damage, high serum c Tn I, and NT-pro BNP levels. CHE injection before EP did not abolish the protection of EP. Both exhaustive exercise and EP produced a significant increase in PKCσ and p-PKCσ Thr507 protein levels in cardiomyocytes. However, the immunostaining of p-PKCσ Thr507 in EP cardiomyocytes was primarily localized to intercalated disks and nuclei while the exhaustive exercise-induced high level p-PKCσ Thr507 was mainly distributed in the cytoplasm. Moreover, the high PKCσ and p-PKCσ Thr507 levels in exhaustive exercise were significantly down-regulated by EP. CHE did not attenuate the expressions of PKCσ and p-PKCσ Thr507. These results indicate that an appropriate activation and translocation of PKCd may represent a mechanism whereby EP can exert an early cardioprotection against exhaustive exerciseinduced myocardial injury.