Hypotensive Effect of Chronic Intrarenal Infusion of Acetylcholine During Angiotensin Hypertension

We examined the role of the pressure natriuresis phenomenon in long-term arterial pressure control. Uni-nephrectomized dogs were housed in metabolic cages and made hypertensive with a continuous background intravenous infusion of angiotensin 11 (AngII, 12 ng/kg/min). To increase the ability of the kidney to excrete salt and water, we infused acetylcholine (ACH, 2.0 μg/kg/ min), a potent natriuretic agent, directly into the renal artery. In four dogs, ACH decreased mean arterial pressure (MAP) from 144 ± 5 mm Hg to 113 ± 3 mm Hg. Sodium excretion increased by about 60% on the first day of infusion and then returned rapidly toward the control value. On cessation of the ACH infusion, there was a transient but marked sodium retention, and the hypertension returned. A control infusion of ACH intravenously rather than into the renal artery in the same four dogs did not affect MAP or sodium excretion during AngII hypertension. Am J Hypertens 1:67-69, 1988