ROLE OF THE AUTONOMIC NERVOUS SYSTEM IN THE ACUTE RESPONSES TO RENAL ARTERY PRESSURE REDUCTION IN CONSCIOUS DOGS

1. Plasma renin and arterial pressure responses to acute renal artery pressure reduction were compared in intact dogs and ‘autonomically-blocked’ dogs subjected to adrenalectomy, chronic guanethidine treatment and acute vagal block (methscopolamine). 2. Following reduction of renal artery pressure plasma renin activity and concentration rose more in the autonomically blocked dogs than in the intact dogs. When renal artery pressure was held at 30 mmHg for 1 h, plasma renin activity rose by 19-1 ng/ml per h (range 11-6-28-7) in autonomically blocked dogs and 3-65 ng/ml per h (range 1-54-5-89) in intact dogs. When renal artery pressure was held at 60 mmHg plasma renin activity rose 3-28 ng/ml per h (range 2-4-4-7) and 1-90 ng/ml per h (range 1-30-3-56), respectively. 3. Arterial blood pressure also rose more in autonomically blocked dogs in accord with the greater rise in plasma renin activity. The relationships between the increases in arterial pressure and plasma renin were closely similar in the two groups. 4. We conclude that the relase of renin and increase in arterial blood pressure in response to renal artery stenosis is normally inhibited by arterial baroreflexes.