Cilazapril inhibits vascular responses to baroreflex-stimulated sympathetic neural activity in hypertensive patients

Abstract

The responses of forearm bloodflow and heart rate to the Valsalva maneuvre were investigated in patients treated with placebo or cilazapril, a new angiotensin converting enzyme inhibitor. Twenty-four uncomplicated hypertensives, whose sitting diastolic blood pressures remained within 94 to 114 mmHg after four weeks of placebo therapy, were randomly assigned on a double-blind basis to receive either further placebo or cilazapril (1.25 to 5.0 mg/day, single dose) for a further four weeks. At the end of weeks 4 and 8, each patient performed standardized Valsalva maneuvres before and 2 h after the day's dose of medication. For each maneuvre, forearm bloodflow was measured in the resting phase and at the point of maximum tachycardia during the straining phase, together with a continuous record of heart rate. All patients exhibited the appropriate heart rate response to the maneuvre with marked tachycardia followed by bradycardia on release of straining. There were no differences in the degree of tachycardia, bradycardia or the Valsalva ratio as a result of cilazapril therapy. There were no changes in resting forearm bloodflow as a result of drug therapy but the flow was reduced (P less than 0.01) during the straining period of all maneuvres. The relative decrease in flow during the maneuvre was attenuated (P less than 0.05) in the cilazapril-treated patients at all drug doses but not in those taking placebo. Cilazapril appears to inhibit the sympathetic nervous system response to the baroreceptor stimulation of the Valsalva maneuvre but not the parasympathetic response of heart rate.