Time course of cardiac sympathetic and vagal tone changes in renovascular hypertensive rats.

The present study has examined the time course of autonomic tone changes in two-kidney, one-clip (2K1C) and one-kidney, one-clip (1K1C) renal hypertension. In conscious rats, cardiac sympathetic and vagal tone were determined using propranolol and atropine, respectively. The development of renovascular hypertension was accompanied by a significant tachycardia, increase in cardiac sympathetic tone and decrease in cardiac vagal tone. In the isolated perfused heart we observed a reduced chronotropic response to isoproterenol. These alterations were transitory in 2K1C and greater and more persistent in 1K1C renal hypertension. These results show the relative role played by the cardiac sympathetic and vagal systems in the maintenance of tachycardia in renovascular hypertension.