[Effects of diltiazem on developing blood pressure and accompanying cardiac and vascular hypertrophy in SHR].

To study the effects of Ca antagonists on hypertension induced cardiac and vascular hypertrophy, diltiazem, at the doses of 30 and 60 mg/kg, p.o., twice a day was administered to SHR from 4 to 16 weeks of age. In addition to suppression of developing blood pressure, left ventricular wet weight was significantly decreased in diltiazem treated SHR. Calcium contents of the abdominal aorta was significantly decreased in this group. On the other hand, in SHR, diltiazem at the dose of 60 mg/kg, p.o., decreased mean blood pressure about 45 mmHg and decreased heart rate about 70 beats/min. Plasma renin activity was significantly elevated, but plasma aldosterone concentration was not changed under this condition. In conclusion, diltiazem can suppress hypertension induced cardiac hypertrophy. In addition to the decrease in the afterload, moderate baroreflex induced augmentation of sympathetic drive and lack of volume overload through the renin-angiotensin-aldosterone system was shown to contribute to this effect.