Potentiation of beta-adrenergic affects on plasma renin concentration by pentobarbital anesthesia

Potentiation of renin release can be achieved by combining adrenergic stimulation and renal vasodilatation. To examine whether pentobarbital anesthesia influences plasma renin concentration (PRC) by its vasodilatory effect, experiments were performed in rats subjected to increasing levels of adrenergic activity. PRC was two- to fourfold higher in anesthetized than in conscious rats when the beta-adrenoceptor agonist isoproterenol HCl (0.05-3.2 micrograms kg-1 min-1) was infused. The sympathomimetic agent tyramine suppressed and the alpha-adrenoceptor blocker phenoxybenzamine enhanced to the same extent the isoproterenol-stimulated PRC in conscious and anesthetized animals. Chronic renal denervation did not abolish the isoproterenol-pentobarbital synergistic effect on PRC. These results are consistent with the view that the renin response to pentobarbital anesthesia is somehow related to the vascular effects of the anesthetic.