Effect of exogenous urotensin-II on vascular tone in skin microcirculation of patients with essential hypertension

Abstract

Background: Plasma levels of urotensin-II (U-II) have been found to be elevated in patients with essential hypertension. However, the consequence of activation of the U-II system have not been previously determined in these patients. We therefore compared the effect of exogenous U-II administration on vascular tone in hypertensive patients (n = 13) and normotensive subjects (n = 14). Methods: The effect of U-II on vascular tone was determined in the forearm skin microcirculation using iontophoresis to administer the drug and laser Doppler velocimetry to measure microvascular response. Results: The U-II administration was associated with a dose-dependent vasodilator response from baseline in normotensive subjects (U-II 1 × 10-12 mol/L, 609 ± 164; U-II 1 × 10-9 mol/L, 839 ± 216; U-II, 1 × 10-7 mol/L, 1249 ± 228 arbitrary flux units; P < .001). In contrast, there was no significant difference in flux between baseline and U-II in either group (or between groups) when the opposite polarity was applied. Conclusions: The demonstration of opposing effects of exogenous U-II in patients with hypertension and normal subjects suggests that U-II may be contributory to the increased vascular tone of these patients. © 2005 American Journal of Hypertension, Ltd.