Abstract: Objective To address the involvement of C3G (CrkSH3－binding guanine nucleotide exchange factor) in the acceleration of post-infarction cardiac remodeling induced by isoproterenol (ISO), C3G protein expression was investigated in myocardium around the infarcted zones in rats with ISO stimulation or not. Methods Myocardial infarction (MI) and sham-operation models were established by Litwin’s method. Seven days after operation, surviving rats were divided into MI, Sham, MI+ISO and Sham+ISO groups respectively, and were treated with physiological buffered saline 5ml/kg or ISO 5mg/kg intraperitoneally once every 3 days for 12 weeks respectively. C3G protein expression in myocardium around the infarcted zones was detected by Western blot. Results Twelve weeks after treatment, the normalized integral optical density (IOD) of C3G protein expression was (1.14±0.29, n=8) in the MI group, (0.90±0.10，n=6) in the Sham group, (1.51±0.18，n=10) in the MI+ISO group and (0.97±0.26, n=8) in the Sham+ISO group respectively. The C3G protein expression in myocardium around the infarcted zones was significantly increased in the MI group compared with the Sham group, and in the MI+ISO group compared with the Sham+ISO group, and in the MI+ISO group compared with the MI group respectively (All P<0.05). Conclusions C3G protein expression was significantly increased in myocardium around the infarcted zones. Moreover, ISO can further up-regulate its expressions in myocardium around the infarcted zones. The increase of C3G protein expression is involved in the post-infarction cardiac remodeling, ischemic cardiomyopathy and heart failure; Furthermore, its further increased expression is also involved in the acceleration of post-infarction cardiac remodeling, ischemic cardiomyopathy and heart failure induced by ISO.

Key words: guanine nucleotide exchange factor, C3G, myocardial infarction, isoproterenol