Effect of propranolol and theophylline on renin release caused by furosemide in the cat

Abstract

Pretreatment with propranolol did not significantly modify the marked increase in plasma renin activity (PRA) produced by furosemide administration in anaesthetized, renally-denervated cats. Treatment with propranolol alone significantly lowered PRA. Theophylline, administered i.v. at the human therapeutic dose of 7 mg/kg, did not affect the level of PRA. When theophylline was superimposed on furosemide no potentiation of the effect on PRA was observed. Conversely, when furosemide was superimposed on theophylline the effect was similar to that produced by furosemide alone. These results indicate that, in contrast to neural stimulation, the release of renin in response to furosemide is not propranolol sensitive. Further, they suggest that the release of renin, in the renally-denervated cat, is not mediated through cyclic AMP, if the therapeutic level of theophylline effectively inhibits phosphodiesterase in the kidney.