Effects of tetradecapeptide renin substrate on isolated preparations of rat caudal artery, guinea-pig atria and on pithed rat blood pressure.

In rat isolated caudal artery preparations, tetradecapeptide renin substrate enhanced the responses to sympathetic nerve stimulation (0.5 Hz, 10 s). In guinea-pig isolated atria, previously incubated in 3H-noradrenaline, tetradecapeptide renin substrate enhanced the stimulation-induced efflux of radioactivity. The facilitation of noradrenergic transmission in rat caudal arteries and guinea-pig atria was blocked by the angiotensin II receptor antagonist saralasin, but was not altered by converting enzyme inhibitors. In the pithed rat tetradecapeptide renin substrate increased blood pressure and this effect was reduced by the converting enzyme inhibitor, captopril.