Abstract: AIM: To study the preventive effect of amiloride on Ca²⁺i in single myocardial cells with the model of the left ventricle hypertrophied(LVH) rats inducd by partial ligation of the abdominal aorta. METHODS: Using Fura 2/AM as a fluoresent indicator. RESULTS: The resting Ca²⁺i of the LVH group was increased significantly compared with that of the control group, but the Ca²⁺i of the amiloride and enalapril groups was decreased markedly than that of the LVH group. After pretreatment with pertussis toxin (PTX, 100 ng·L^-1) for 5 h, the resting Ca²⁺i was not changed. But the elevation of Ca²⁺i , stimulated by the NE, was inhibited significantly, especially in the LVH group(P<0 01). CONCLUSION: The elevation of Ca²⁺i in single myocardial cells, stimulated by NE, may relate to the PTX sensitive G protein. This pathway may increase in myocardial cells of the LVH rats.