Cutaneous Vasodilation to Acetylcholine in Patients with Essential Hypertension

Endothelium-dependent vasodilation is reduced in the forearm of patients with essential hypertension. To evaluate whether endothelium-dependent vasodilation is also reduced in the skin microcirculation of patients with essential hypertension, we evaluated the effect of acetylcholine, an endothelium-dependent vasodilator, and sodium nitroprusside, an endothelium-independent vasodilator, on cutaneous and total forearm blood flow in normotensive subjects (n = 8) and matched patients with essential hypertension (n = 9). We infused acetylcholine (0.15, 0.45, 1.5, 4.5, and 15 μg/100 ml forearm tissue/min) and sodium nitroprusside (1, 2, and 4 μg/100 ml forearm tissue/min) into the brachial artery, and we measured cutaneous blood flow (laser Doppler flowmeter) and muscle blood flow (strain-gauge venous plethysmography) modifications. Both the cutaneous and muscle blood flow increases induced by acetylcholine were reduced in patients with essential hypertension as compared with normotensive controls, whereas the skin and muscle vasodilation induced by sodium nitroprusside was similar in the two groups of patients. These data confirm the impairment of endothelium-dependent vasodilation in the muscle vascular bed of patients with essential hypertension and demonstrate the presence of endothelial dysfunction in skin microcirculation.