1. Calcium antagonists of the dihydropyridine type such as nifedipine and nitrendipine are potent antihypertensive drugs in various forms of hypertension in rats. Long term treatment with calcium antagonists lowers high blood pressure and reduces cardiac hypertrophy in spontaneously hypertensive rats and additionally prevents mortality in renal (two-kidney, one-clip) and salt-induced (Dahl salt-sensitive) hypertensive rats.
2. Vasodilators of the hydralazine type only lower blood pressure in spontaneous hypertensive rats but do not influence cardiac hypertrophy. Minoxidil lowers blood pressure in spontaneous and slightly in renal hypertensive rats but does not reduce heart hypertrophy in renal hypertension and may even aggravate hypertrophy in spontaneous and salt-induced hypertension.
3. The antihypertensive effect of calcium antagonists is not only due to peripheral vasodilatation. Calcium antagonists may also improve renal function by lowering renovascular resistance. Reduced volume load may contribute to the reversal of heart hypertrophy seen after calcium antagonists compared with vasodilators.