Suppression of renin release by timolol.
The beta-adrenergic blocking agent, timolol, administered to resting rabbits as an i.v. bolus (0.125 mg/kg) sustained by a 2-hr infusion at 0.0625 mg/kg/hr, caused significant depression of plasma renin activity (PRA) to 49% of the control level. Significant correlations emerged between the fall in mean blood pressure and changes in both heart rate and PRA. Timolol also antagonized isoprenaline-induced renin release. In anaesthetized normal rats, timolol (0.2 mg/kg i.p.) suppressed mean plasma renin concentration (PRC) to 16% of the pre-treatment value. Furthermore, the mean PRC of normal rats, bled immediately after decapitation, to avoid stimulating renin secretion, was reduced by 55% one hr after i.p. injection of timolol. The potency of timolol in this respect was 8 times that of dl-propranolol. Thus, in rabbits and rats, timolol effectively depresses both basal and stimulated plasma renin levels.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003864:Depression, Chemical; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D011188:Potassium / Q000097:blood; D011817:Rabbits; D051381:Rats; D012083:Renin / Q000097:blood*; D012964:Sodium / Q000097:blood
D000319:Adrenergic beta-Antagonists; D012964:Sodium; D012083:Renin; D007545:Isoproterenol; D011188:Potassium