Altered pressor responses in long-term nitrendipine treatment.

The effect of long-term treatment with nitrendipine on systemic pressor responses to norepinephrine (NE) and angiotensin II (AII) was evaluated in 11 subjects with mild, uncomplicated hypertension. Pressor responses to NE and AII were measured at the end of a 4-wk placebo period and after 5 wk treatment with nitrendipine (final dose 16 mg twice daily; range 5 to 20 mg/day) or placebo. In subjects who received nitrendipine, clinic supine blood pressure was reduced from 152 +/- 12/96 +/- 4 mm Hg to 134 +/- 11/84 +/- 5 mm Hg and pressor responses to NE but not to AII were attenuated. Endogenous plasma levels of NE and renin activity were not changed by nitrendipine. Data suggest that noradrenergic blood pressure control mechanisms depend more on cellular calcium transport than do AII-mediated ones and may help explain the greater effectiveness of calcium entry blockers in the treatment of low-renin hypertension.