EFFECTS OF CENTRALLY ADMINISTERED PROPRANOLOL ON PLASMA-RENIN ACTIVITY, PLASMA NOREPINEPHRINE AND ARTERIAL-PRESSURE

Single doses of d,l-propranolol (0.1-0.5 mg/kg) administered intarcisternally (IC) to anesthetized dogs produced dose-dependent decreases in plasma renin activity and mean arterial pressure whereas identical doses given intravenously had no significant effect on these parameters. Intracisternal d,l-propranolol also significantly reduced circulating norepinephrine levels concomitant with the renin suppressing and hypotensive effects. Acute renal denervation abolished the renin suppressing, but not the hypotensive effect of intracisternal d,l-propranolol. Both d- and l-propranolol administered intracisternally significantly lowered plasma renin activity and arterial pressure to a similar degree, but intracisternal lidocaine had no effect on these parameters. These results indicate that propranolol can suppress plasma renin activity through an action within the central nervous system and suggest that both the renin suppression and hypotension produced by intracisternal propranolol resulted from a centrally mediated reduction in peripheral sympathetic activity. The equal potency of the stereoisomers of propranolol and the observed differences between the effect of propranolol and lidocaine suggest that these central actions involve a mechanism that may be independent of beta receptor blockade or the local anesthetic properties of drug. © 1979.