Non-invasive assessment of microvascular endothelial function by laser Doppler flowmetry in patients with essential hypertension.

The aim of the study was to investigate the endothelium-dependent vasodilation in the forearm skin using two non-invasive laser Doppler applications in patients with essential hypertension (EHT) and in normotensive (NT) control subjects. The effect of two consecutive doses of acetylcholine (ACh) and that of sodium nitroprusside (SNP) on the skin microcirculation, and thereafter the postocclusive reactive hyperaemic (PORH) response, were measured in 25 patients with essential hypertension and also in 25 control normotensive healthy subjects. The plasma von Willebrand factor (vWF) level and activity were also determined. The average peakflow in PORH was 287 +/- 31.5% (x +/- S.E.M.) in EHT and 410.28 +/- 35.08% in NT (P < 0.01). The average hyperaemic response to the two doses of ACh-iontophoresis was 206.36 +/- 33.97 and 568.76 +/- 54.23% in EHT and 444.24 +/- 80.28 and 804.12 +/- 93.07% in NT (P < 0.01, 0.05). The response to SNP was similar in the two groups. The vWF levels were 122.5 +/- 13.2 and 89.6 +/- 8.1% (P = 0.0595, NS), the activities were 80.8 +/- 5.5 and 68.9 +/- 6.1% (P = 0.157, NS) in EHT and in NT, respectively. These results demonstrate that essential hypertension is associated with endothelial dysfunction in the skin microcirculation of the forearm.