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Suppression of renin release by timolol
Archives Internationales De Pharmacodynamie Et De Therapie
|February 1, 1976
Summary
Timolol, a beta-adrenergic blocker, significantly lowers plasma renin activity and concentration in rabbits and rats. This drug effectively reduces both basal and stimulated renin release, impacting blood pressure and heart rate.
Area of Science:
- Pharmacology
- Cardiovascular Physiology
Background:
- The renin-angiotensin-aldosterone system (RAAS) plays a crucial role in regulating blood pressure and fluid balance.
- Beta-adrenergic receptors influence renin release from the kidneys.
Purpose of the Study:
- To investigate the effect of timolol, a beta-adrenergic blocking agent, on plasma renin levels in animal models.
- To determine if timolol can suppress both basal and stimulated renin release.
Main Methods:
- Administered intravenous timolol to rabbits and intraperitoneal timolol to rats.
- Measured plasma renin activity (PRA) and plasma renin concentration (PRC) before and after timolol administration.
- Assessed the correlation between blood pressure, heart rate, and PRA changes.
- Investigated timolol's effect on isoprenaline-induced renin release and compared its potency to dl-propranolol.
Main Results:
- Timolol significantly reduced PRA in rabbits by 49% and PRC in rats by 84% (basal) and 55% (post-decapitation).
- Correlations were found between decreased blood pressure, heart rate, and PRA.
- Timolol antagonized isoprenaline-stimulated renin release.
- Timolol demonstrated higher potency in suppressing renin levels compared to dl-propranolol.
Conclusions:
- Timolol effectively depresses both basal and stimulated plasma renin levels in rabbits and rats.
- These findings suggest a significant role for beta-adrenergic blockade in modulating the renin-angiotensin system.