Attenuation of neurogenic hypertension by chronic converting enzyme inhibition.

We compared the effects produced by acute and chronic administration of captopril in sinoaortic denervated rats. In conscious undisturbed rats acute administration of captopril (10 mg/kg intravenously) produced acute transient reductions in mean arterial pressure of 16 and 26%, 6 h (mean arterial pressure 148 +/- 4 mmHg) and 24 h (133 +/- 3 mmHg) after the sinoaortic denervation, respectively. Chronic captopril treatment (30 mg/day orally) produced a permanent attenuation of the hypertension induced by sino-aortic denervation, as shown by a beat-to-beat analysis of arterial pressure for 80 min. The attenuation was 11% (131 +/- 7 versus 148 +/- 4 mmHg) and 24% (103 +/- 9 versus 133 +/- 3 mmHg) in rats studied 6 and 24 h after the sinoaortic denervation, respectively. Chronic captopril administration produced no alteration in the tachycardia, nor in the heart rate variability of the sinoaortic denervated rats; the latter was lower than that of normotensive rats. These data show that while acute administration of captopril in sinoaortic denervated rats produced a rapid hypotensive response, chronic administration produced a long-lasting attenuation of hypertension, presumably by interference with sympathetic cardiovascular control.