[Impairment of renal cortical blood flow autoregulation induced by reserpine, guanethidine or propranolol (author's transl)].

Local blood flow was measured in renal cortex (at 1 mm below cortical surface) by means of the hydrogen clearance method in urethanized rats. Recording of blood pressure from femoral artery was performed. The blood flow autoregulation was studied by plotting renal cortical vascular resistance (R.C.V.R.) as a function of arterial pressure in all the experimental conditions. R.C.V.R. was calculated as arterial pressure/blood flow ratio. In control animals R.C.V.R. was linearly correlated to arterial pressure; this implies the existence of autoregulation in the studied zone. In animals pretreated with guanethidine or propranolol, and in animals injected with propranolol immediately before the experiment, the increase of arterial pressure was not followed by an increase in R.C.V.R.; this implies that autoregulation was absent. In animals pretreated with reserpine the increase of arterial pressure was not followed by a significant increase in R.C.V.R., although a tendency to increase was detected. It is suggested that the impairment of autoregulation induced by guanethidine, propranolol or reserpine may be due to an inhibition of renin release. The results obtained with guanethidine and reserpine may be partially attributable to a decrease in adrenergic activity on the vascular smooth muscle of the studied zone, although other mechanisms cannot be discarded.