Objective:To observe the role of calcium sensing receptor(CaSR) in apoptosis of rat cardiomyocyte induced by hypoxia/reoxygenation(H/R). Methods:After myocardial hypoxia/reoxygenation model was established by culturing primary myocardial cell of neonatal rat in vivo. The myocardial cells were divided into seven groups, the control group,H/R group,calcimimetic group(Ldcl3 group),inhibitor group,small-(10 ng/ml),middle-(20 ng/ml) and large-dose(40 ng/ml) of hepatocyte growth factor(HGF) group. The apoptotic rate of myocardial cells was determined by TUNEL assay, the expression of TNF-α was detected by reverse transcriptase polymerase chain reaction(RT-PCR), and the level of serum lactate dehydrogenase(LDH) was measured by LDH kit. Results:In H/R and Ldcl3 group,there was significant increase in the apoptotic rate ,the levels of LDH and the expression of TNF-α compared to the control group(P < 0.01). However, the above indexes did not significantly decrease in inhibitor group, compared to Ldcl3 group, but significantly decreased in a dose-depended manner in HGF groups. Conclusion:CaSR activation may be partly associated with myocardial ischemia/reperfusion injury by increasing oxidative damage, promoting the expression of inflammatory factor like TNF--琢 and causing intracellular calcium overload, which could accelerate apoptosis. However, HGF could suppress the myocytes apoptosis to protect cardiomyocyte in a dose-effect manner.