Skin blood flow during vasoconstrictive and vasodilative stimuli in essential hypertension patients: a laser Doppler flowmetry study

In order to compare the extent of the elicited vasoconstrictive and vasodilative response at the microcirculatory level in essential hypertension (EH), we measured the skin blood flow by means of a laser Doppler flowmeter (LDF). Thirty-four mild-to-moderate EH patients were enrolled. Twenty-two sex- and age-matched healthy subjects were selected as a control group. The LDF measurements were carried out with the probe over the fingertip of the distal phalanx at baseline conditions (Rest flow, RF), after an ischaemic test (post-ischaemic peak flow) and during an arithmetic stress test (AT). The flow was expressed in arbitrary units. The data were processed using the Perisoft computer program. The relative flows after the ischaemic test (Rel F1) and during the AT (Rel F2) were expressed as a percentage of the previous RF values (RF1 and RF2, respectively). During the AT, the lag time was calculated (in seconds). As compared to the control subjects, RF was significantly lower in the EH group (p < 0.01). During the AT, the EH patients showed a statistically lower mean Rel F2 decrease compared to the control subjects (p < 0.01). No statistically significant difference occurred in the Rel F1 and lag time. These data suggest that the vasoconstrictive capacity of the precapillary vessels is impaired in patients with hypertension.