title: Late cardioprotection of exercise preconditioning against exhaustive exercise-induced myocardial injury by up-regulatation of connexin 43 expression in rat hearts.
abstract: OBJECTIVE
  To investigate the expression of myocardium connexin 43 (Cx43) in late exercise preconditioning (LEP) cardioprotection.
  
  
  METHODS
  Eight-week-old adult male Sprague Dawley rats were randomly assigned into four groups (n = 8). Myocardial injury was judged in accordance with serum levels of cTnⅠ and NT-proBNP as well as hematoxylin basicfuchsin picric acid staining of myocardium. Cx43 mRNA was detected by in situ hybridization and qualified by real-time fluorescence quantitative PCR. Cx43 protein was localized by immunohistochemistry and its expression level was determined by western blotting.
  
  
  RESULTS
  The LEP obviously attenuated the myocardial ischemia/hypoxia injury caused by exhaustive exercise. There was no significant difference of Cx43 mRNA level between the four groups. Cx43 protein level was decreased significantly in group EE (P < 0.05). However, LEP produced a significant increase in Cx43 protein level (P < 0.05), and the decreased Cx43 protein level in exhaustive exercise was significantly up-regulated by LEP (P < 0.05).
  
  
  CONCLUSIONS
  LEP protects rat heart against exhaustive exercise-induced myocardial injury by up-regulating the expression of myocardial Cx43.
authors: College of Sports Science, Qufu Normal University, Qufu 273165, China.
authors: Kai
authors: K
authors: Wang
authors: Department of Physical Education, Hainan Medical University, Haikou 571100, China. Electronic address: baichaoty@163.com.
authors: Bai-Chao
authors: BC
authors: Xu
authors: College of Sports Science, Qufu Normal University, Qufu 273165, China.
authors: Hai-Yun
authors: HY
authors: Duan
authors: Department of Physical Education, Hainan Medical University, Haikou 571100, China.
authors: Hua
authors: H
authors: Zhang
authors: QiongZhou University Physical Test Room, Sanya 572022, China.
authors: Fu-Song
authors: FS
authors: Hu
keywords: Cardioprotection; Connexin 43; Exercise preconditioning; Exhaustive exercise; Myocardial injury