Effects of Shenfu injection on myocardial adenosine receptors in rats with myocardial ischemia-reperfusion postconditioning

Objective Shenfu injection (SFI) has been reported to have a protection against myocardial ischemia-reperfusion (MI/R) injury. However, the changes of adenosine receptors in MI/R postconditioning when pretreated with SFI are unclear. Methods Forty-five rats were randomly divided into sham group (sham), MI/R postconditioning group (MI/R-post), low-dose SFI group (1 mL/kg), middle-dose SFI group (2.5 mL/kg), and high-dose SFI group (5 mL/kg). In SFI groups, SFI was intravenously injected before reperfusion, and rats were treated with ischemic postconditioning after ischemia for 30 min. After 24 h of reperfusion, the levels of Ca2+ and cAMP in blood platelets were analyzed. Myocardial infarct volume and myocardial pathology were observed. The levels of adenosine receptor subtypes A1, A2b, and A3 in myocardium were analyzed using immunohistochemistry and Western blot. The oxidative stress–related indicators were also observed. Results Compared with the MI/R-post group, SFI ameliorated the MI/R injury by decreasing the myocardial infarct area, oxidative stress, and concentration of Ca2+ and cAMP (p < 0.01). Pretreatment with SFI enhanced the expression of adenosine receptors A1 and A2b in a dose manner compared with the MI/R-post group. In contrast, the levels of adenosine receptor A3 were increased after MI/R postconditioning compared with the sham group, and its expression continued to increase with the increase of SFI. Furthermore, the oxidative stress reduced with the concentrations of SFI. Conclusion These results demonstrated that pretreatment with SFI might regulate the expression of adenosine receptors to improve the MI/R postconditioning.