Effect of Ganglion-Blocking Agents on Renin Release in Hypertensive Patients

Abstract

In 18 patients with benign essential hypertension, renin release during reduction of arterial pressure due to sodium nitroprusside infusion was measured before and after administration of ganglion-blocking agents (pentolinium or trimethaphan). In 12 patients, renin release induced by reduction in pressure was significantly reduced but not abolished by ganglion blockade. Simultaneously, ganglion blockade significantly reduced renal vascular resistance (RVR) and almost abolished a decrease in renal blood flow (RBF) due to hypotension. In 6 other patients in whom no significant renin release resulted from hypotension, ganglion blockade caused little changes in renin release, RVR or RBF. The results support the hypothesis that renal sympathetic nerve activity is a factor in variations in renin release in patients with essential hypertension. Following ganglion blockade in the responsive patients, the significant reciprocal correlation between renal venous renin activity and sodium excretion rate shifted but still persisted, suggesting that the renin-releasing mechanism related to sodium excretion may be independent of innervation. On the other hand, the correlation between renin activity and the degree of reduction in pressure was insignificant after ganglion blockade. It is concluded that two intrarenal mechanisms, nerve-dependent and nerve-independent, are involved in renin release due to reduction in pressure. Ganglion blockade also exerted an inhibitory effect on renin release due to hypotension in 4 normotensive subjects and 5 patients with renovascular hypertension.