Hemodynamic effects of nifedipine in hypertension in the presence of elevated angiotensin-II and beta-adrenergic blockade.

The hemodynamic effects of the slow release form of a calcium channel blocker, nifedipine retard, in essential hypertension patients after angiotensin II (AII) infusion were studied using nuclear ventriculography. Sublingual nifedipine lowered blood pressure that had been acutely raised by an infusion of AII to its baseline level. When used for 4 weeks, nifedipine retard maintained its blood-pressure-lowering effects without a change in heart rate, both when used alone and when used in addition to beta-adrenergic blockers. In the patients with untreated essential hypertension, nifedipine counteracted the lowering effect of AII on left ventricular ejection fraction (LVEF), which was 67.5 +/- 8.9% at recumbency, 61.2 +/- 6.6% (+/- SD) during AII infusion, and 72.1 +/- 7.5% 30 minutes after sublingual nifedipine. These acute effects seem to result from a marked reduction in total peripheral resistance (TPR) and are accompanied by a rise in cardiac index (CI). The TPR, in dynes/sec/cm-5, was 1376.9 +/- 275.8 at recumbency, 2000.7 +/- 358 during AII infusion, and 1228.6 +/- 289 30 minutes after sublingual nifedipine. The corresponding figures for CI in liters/M2 BSA, were 4.02 +/- 0.77, 3.03 +/- 0.64, and 4.32 +/- 0.79. In patients receiving beta-blocker therapy (propranolol or atenolol) with inadequate control of blood pressure, similar results were obtained in LVEF (69.7 +/- 8.87% at recumbency, 63.7 +/- 11.9% during AII infusion, and 72.2 +/- 6.05% 30 minutes after sublingual nifedipine). The initial TPR was much higher than that of untreated essential hypertensive patients. Nevertheless, the increase obtained during AII infusion was counteracted by sublingual nifedipine. CI was decreased by AII.(ABSTRACT TRUNCATED AT 250 WORDS)