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 NG‐monometil‐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.