Cardiovascular and hormonal responses to DDAVP before and after beta-blockade in patients with mild essential hypertension.

The aim of this study was to assess the cardiovascular and hormonal responses to 1-desamino-8,D-arginine vasopressin (DDAVP) in hypertensive patients before and after non-selective beta-blockade. We infused DDAVP at 400 ng/kg body weight for 10 min in nine subjects with mild essential hypertension before and 14 days after administration of nadolol at 80 mg/day. Blood pressure and heart rate were recorded, and blood was drawn at 0, 30 and 60 min for measurement of plasma renin activity, aldosterone, cortisol, noradrenaline, adrenaline and dopamine. Before the administration of nadolol, DDAVP induced a significant decrease in blood pressure, and significant increases in the heart rate, plasma renin activity, cortisol and noradrenaline; there were no changes in adrenaline or dopamine. After the administration of nadolol, baseline noradrenaline was significantly increased, while cortisol, adrenaline and dopamine remained unchanged. A second infusion of DDAVP did not significantly alter blood pressure, [corrected] heart rate, noradrenaline, adrenaline or dopamine, but plasma renin activity, aldosterone and cortisol still showed a significant increase. The blunted hypotensive effect of DDAVP after the administration of nadolol may be aspecific, due to lower basal blood pressure levels, or may indicate a mechanism of action common to both drugs. A similar post-DDAVP increase before and after beta-blockade suggests that the drug has a direct effect on the renin-secretory apparatus. An indirect effect, mediated by changes in intrarenal haemodynamics or by other factors with renin-stimulating activity, e.g. tissue plasminogen activator, can also be hypothesized.