Dose-dependent vasodilatory effects of acetylcholine and local warming on skin microcirculation.

The assessment of the skin microvasculature response to iontophoretically applied acetylcholine (ACh) and local warming makes it possible to explore noninvasively in humans the functional integrity of endothelium. The present study aimed to examine whether these two stimuli of nitric oxide (NO) release have a dose-dependent vasorelaxant activity. For this purpose we assessed in healthy subjects using a laser-Doppler imaging system the increase in forearm blood flow following transdermal application of increasing amounts of ACh [with an iontophoretic current of either 0.

Acetylcholine-induced vasodilation and reactive hyperemia are not affected by acute cyclo-oxygenase inhibition in human skin.

Objective: To examine whether prostaglandins are involved in endothelium-dependent vasodilatory responses of the skin microcirculation.

Methods: Twenty-three young male volunteers were studied on 2 different days 1-3 weeks apart. On each experimental day the forearm skin blood flow response to iontophoretically applied acetylcholine (Ach, an endothelium-dependent vasodilator) was determined with laser Doppler imaging following the intravenous administration of either the cyclo-oxygenase inhibitor lysine acetylsalicylate (L-AS), 900 mg, or the oral intake of indomethacin, 75 mg.

Local heating of human skin causes hyperemia without mediation by muscarinic cholinergic receptors or prostanoids.

Local changes in surface temperature have a powerful influence on the perfusion of human skin. Heating increases local skin blood flow, but the mechanisms and mediators of this response (thermal hyperemia response) are incompletely elucidated. In the present study, we examined the possible dependence of the thermal hyperemia response on stimulation of muscarinic cholinergic receptors and on production of vasodilator prostanoids.

Endurance training enhances vasodilation induced by nitric oxide in human skin.

Endurance training modifies the thermoregulatory control of skin blood flow, as manifested by a greater augmentation of skin perfusion for the same increase in core temperature in athletes, in comparison with sedentary subjects. In this study, we tested the hypothesis that a component of this adaptation might reside in a higher ability of cutaneous blood vessels to respond to vasodilatory stimuli. We recruited healthy nonsmoking males, either endurance trained or sedentary, in two different age ranges (18-35 y and >50 y).

Endothelium-dependent vasodilation in the skin microcirculation of patients with septic shock.

The evidence for endothelial dysfunction in sepsis is mostly restricted to animal models. We investigated endothelial function in the skin microcirculation of eight patients hospitalized for septic shock in an intensive care unit (ICU). All patients required adrenergic support.