Skin vasodilator effect of exogenous urotensin-II in hypertensives not exposed to antihypertensive medication

To investigate the effect of urotensin-II (U-II) on skin vascular tone in normotensive subjects and in patients with essential arterial hypertension (EHT), forearm skin blood flux and skin blood flowmotion (SBF) response to U-II cathodal iontophoresis was investigated using laser Doppler flowmetry (LDF) and spectral Fourier analysis in 10 young normotensive subjects, before and after intra-dermal injection of the nitric oxide synthetase inhibitor N-G-monometi-L-arginine (L-NMMA). Forearm skin blood flux response to U-II cathodal iontophoresis was also investigated using LDF in 15 newly diagnosed EHT patients, in 15 long-standing EHT patients and in 15 age- and sex-matched normotensive subjects. Intra-dermal injection of L-NMMA significantly blunted the increase in skin blood flux (from 342.5 +/- 153.0% to 193.5 +/- 78.9%, p < 0.05) and completely inhibited the increase in spectral amplitude of 0.009-1.6 Hz total-spectrum SBF, as well as of the 0.009-0.02 Hz component, related to endothelial activity, which occurred following U-II iontophoresis in normotensive subjects. A significant increase in skin blood flux compared with baseline was also induced by U-II iontophoresis in newly diagnosed (354 +/- 195% change from baseline) and long-standing patient (324 +/- 180% change from baseline), without significant difference with normotensive subjects (400 +/- 251% change from baseline). These findings demonstrate that: (i) U-II exerts a skin vasodilator effect in normotensive subjects, which is partly endothelial-dependent; (ii) U-II skin vasodilator effect is preserved in newly diagnosed and in long-standing EHT patients.