Effects of antihypertensive treatment on systolic blood pressure and renin in experimental hypertension in rats.

The effects of pretreatment with hydralazine and alpha-methyldopa were assessed in rats made hypertensive by ligation of the left renal artery (LRA). Systolic blood pressure and peripheral renin activity (PRA) were measured 7 and 1 day before LRA and 2, 7 and 28 days after LRA. Systolic blood pressure increased 2 days after LRA in control and alpha-methyldopa-treated rats but not in the hydralazine-treated rats. Peripheral renin activity levels did not correlate with changes in systolic blood pressure. Peripheral renin activity first increased 7 days after LRA but decreased 28 days after LRA despite persistent hypertension in controls and alpha-methyldopa-treated rats. It is concluded that factors other than renin are involved in the initial and maintenance phases of this experimental model. In addition, hydralazine protects the rat with LRA from developing hypertension.