POTENTIATION OF DURATION OF THE VASODILATOR EFFECT OF BRADYKININ BY SYMPATHOLYTIC DRUGS AND BY RESERPINE

¹ Department of Pharmacology, Faculty of Medicine, University of S. Paulo, Ribeirão Prêto, E. S. Paulo, Brazil

The vasodilator effects of bradykinin were studied in relation to previous injections of common hypotensive drugs: a) a sympatholytic (Dibenzyline); b) a gangliolytic (hexamethonium); and c) centrally acting drugs (Apresoline, chiorpromazine and reserpine). Drugs of groups a and c strongly delayed recovery from hypotension provoked by a standard small dose (25 to 30 units) of bradykinin injected intravenously in cats. Hexamethonium had no potentiating effect. Cocaine had the opposite effect of shortening the time of recovery after the injection of 60 units of bradykinin.

Although most of the potentiation observed might be explained on the basis that the return of the blood pressure to normal level was impaired by the blockade of the peripheral sympathetic receptors at the walls of the blood vessels, or by depletion of the stores of catecholamines in their peripheral stocks, some central component might explain part of the potentiation by reserpine or Apresoline, since bradykinin injected into the carotid artery (through the lingual artery branch) or directly into the cerebral lateral ventricle had a prolonged hypotensive effect. Many of the effects produced by reserpine have also been observed by the cerebral injection of bradykinin.