Antagonistic effect of theophylline on the adenosine-induced decreased in renin release

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Abstract
The action of theophylline on the adenosine-induced decrease in renin release was studied in anesthetized dogs. Adenosine inhibited renin release, decreased glomerular filtration rate [GFR] and fractional Na excretion, and decreased the concentration of angiotensin II in the renal lymph. Theophylline (5 .mu.mol/min intrarenally) had no significant effect on GFR or [RBF] yet produced a significant increase in the release of renin and the fractional excretion of Na. The intrarenal infusion of adenosine (3 .times. 10-7 mol/min) during theophylline infusion produced no effect on GFR or RBF, but fractional Na excretion and renin release were significantly decreased. Adenosine was infused at a lower dose (3 .times. 10-8 mol/min) during theophylline (5 .times. 10-6 mol/min) infusion in a 2nd group of dogs. With the exception of fractional Na excretion, all effects of adenosine were effectively antagonized by theophylline. Theophylline at 5 .times. 10-6 mol/min, which stimulates renin release and effectively antagonizes the renal effects of adenosine, had no detectable effect on cAMP measured in renal cortex. No change in cortical cAMP was observed until theophylline was increased 50-fold over the dose effective in antagonizing adenosine. Theophylline, at concentrations having no effect on cortical cAMP, antagonizes the effect of adenosine on renin release. Theophylline stimulates renin release by a mechanism other than its action on cAMP.

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