The strength of radiation of ⁴⁵Ca²⁺ in sarcoplasmic reticulum vesicle (SR) and mitochondria (Mit) was measured by liguid scintillation counting method. Comparing the effects of ATP - MgCl₂ . SOD and verapamil on the ⁴⁵Ca²⁺ concentration in SR and Mit which prepared from isolated ischemia reperfused rat hearts. The result showed that the ⁴⁵Ca²⁺ cpm of SR of the three groups were higher than that of control, while the ⁴⁵Ca²⁺ cpm of Mit of the three groups were lower than that of control. These results suggested that the three kinds of reagent could protect reperfusion injury of heart cell through enhance ⁴⁵Ca²⁺ storage in SR and inhibitting the ⁴⁵Ca²⁺ accumulation in Mit.