Acute hemodynamic (systemic and renal) and humoral effects of three increasing doses of iloprost in essential hypertensives.

To evaluate the acute hemodynamic, both systemic and renal, and humoral effect of three increasing doses of Iloprost, a prostacyclin analogue, eight uncomplicated untreated hospitalized patients with mild to moderate essential hypertension, while on a constant sodium and potassium intake, received, after oral hydration, three doses of Iloprost (1,2 or 4 ng/kg/body weight for 45 min) in a single-blind randomized sequence. Each dose was preceded by placebo (saline infusion for 45 min) with a 48 h interval between each study. Iloprost significantly (P less than .05) reduced blood pressure, and increased heart rate, filtered sodium, urinary sodium excretion, fractional sodium excretion, noradrenaline, adrenaline, and plasma renin activity (PRA). The blood pressure lowering effect as well as the heart rate, renal plasma flow and noradrenaline increases were significantly greater on the 4 ng dose. Glomerular filtration rate and adrenaline showed a dose-dependent increase; urinary sodium excretion and fractional sodium excretion were similarly increased by the three doses. No correlation was found between urinary sodium excretion and either glomerular filtration rate or renal plasma flow. The data obtained indicate that Iloprost causes reduction of blood pressure with a reflex activation in the sympathetic nervous system and stimulation of renin secretion, renal vasodilation mainly at the level of the afferent arteriole, and natriuresis. This latter effect is probably due to a direct inhibition of tubular reabsorption, which, at variance with the other effects, is dose-independent.