Modulation of cyclic AMP and autoregulation of renal blood flow, analysed by the use of forskolin and 1-methyl-3-isobutylxanthine

Abstract

Abstract We have examined the effects of forskolin and 1-methyl-3-isobutylxanthine (IBMX) in relation to cyclic (c)AMP metabolism and renal blood flow autoregulation in anaesthetized dogs. Control observations usually showed excellent autoregulation of renal blood flow over the renal perfusion pressure range of 120–200 mmHg, when the perfusion pressure was changed, stepwise, between 60 and 200 mmHg. Renal blood flow was increased by the infusion of forskolin (10 μg min−1) and IBMX (100 μg min−1) at the basal perfusion pressure of 100 mmHg, and maintained an increased level while the infusion was continued. Forskolin and IBMX did not inhibit autoregulation, though they shifted the perfusion pressure range evoking autoregulation. These data indicate that vasodilators which may produce the activity through modulating the cAMP level in vascular smooth muscle do not influence the establishment of autoregulation of renal blood flow.