Methods 50 animals were randomly divided into five groups(n=10 in each): control group(A),MIR group(B),MIR+LGT group(C),MIR+L-Arg group(D),MIR+LGT+L-Arg group(E).The mitochondrial respiratory function,Ca²⁺ concentration(m),malondialdehyde(MDA) content and superoxide dismutase(SOD) activity were determined.Meanwhile,the contents of ATP and EC in the myocardial tissue were measured,respectively.Results It was found that mitochondrial respiratory control rate(RCR),state 3 (ST3),SOD,ATP and EC levels of myocardial tissue in C,D,E group were higher than those of B group,but state 4(ST4),m,MDA were lower.However,between E and A group,all parameters had no significant differences.Conclusion LGT and L-Arg can improve function of mitochondria in myocardial cells in the reperfusion injury after myocardial ischemia by decreasing oxygen free radical level and Ca²⁺ overload in the mitochondria.