CHANGES IN PERIPHERAL SYMPATHETIC OUTFLOW OF PITHED SPONTANEOUSLY HYPERTENSIVE RATS AFTER BRADYKININ AND DESARG-BRADYKININ INFUSIONS - INFLUENCE OF CONVERTING-ENZYME INHIBITION

Because converting enzyme and kininase II are identical enzymes and probably influence both the biosynthesis of angiotensin II and the metabolism of bradykinin, we investigated the effects of bradykinin and desArg-bradykinin on the sympathetic outflow of pithed spontaneously hypertensive rats (SHRs) before and after acute or chronic inhibition of the converting enzyme by ramipril. Sympathetic outflow was induced by preganglionic electrical stimulation of the spinal cord and measured as circulating, stimulation dependent norepinephrine and epinephrine by high-performance liquid chromatography (HPLC) and electrochemical detection. Bradykinin increased dose-dependently norepinephrine and epinephrine release, particularly when converting enzyme was inhibited. DesArg-bradykinin did not influence norepinephrine outflow but caused a dose-dependent increase in epinephrine release only after converting-enzyme inhibition. It is suggested that both bradykinin and desArg-bradykinin could compensate for the lack of effect of angiotensin II on sympathetic outflow.