OBJECTIVE To elucidate the role of myocardial angiotensin II and sarcoplasmic reticulum (SR) Ca2+ handling protein (ryanodine receptor and Ca2+ ATPase) in the process of left ventricular hypertrophy. METHODS The myocardial angiotensin II level, Bmax and Kd value of ryanodine receptor and calcium ATPase activity in SR were determined among 3 groups: spontaneously hypertensive rats (SHR), SHR treated with perindopril and WKY. RESULTS The blood pressure (BP) of the SHR group, the ratio of left ventricular weight to body weight (LVW/BW) and the myocardial angiotensin II level were higher than those of the WKY group (P < 0.01), Perindopril decreased the BP(P < 0.01) and the myocardial angiotensin II level, and reversed the LVW/BW of the SHR group (P < 0.05). Compared to the WKY group, the Bmax value of cardiac ryanodine receptor in the SHR group was increased (232 +/- 27) fmol.mg-1 vs (173 +/- 18) fmol.mg-1, (P < 0.01), but there was no difference in Kd value (P > 0.05). The SR calcium ATPase activity was also decreased in the SHR group [(0.52 +/- 0.11) mumol.g-1.min-1 vs (1.03 +/- 0.22) mumol.g-1.min-1, P < 0.01]. In the SHR perindopril treatment group, the Bmax of ryanodine receptor was decreased [(191 +/- 23) fmol.mg-1, P < 0.05]. There was no difference in Kd value. The calcium ATPase activity was increased [(0.82 +/- 0.28) mumol.g-1.min-1, P < 0.05)]. CONCLUSIONS The left ventricular hypertrophy is closely related to the myocardial angiotensin II and the SR calcium handling protein.