Microvascular reactivity in normotensive subjects with a familial predisposition to hypertension

Using the laser-Doppler method we measured blood flow on the nailfold skin to compare the reactivity of cutaneous microcirculation in three groups of normotensive subjects: 11 subjects with a familial predisposition to hypertension without a previous record of high blood pressure, 6 predisposed subjects with a previous record of high blood pressure, and 13 subjects with no predisposition to hypertension. The flow was measured after direct and indirect skin cooling and heating and during postocclusive reactive hyperemia (PRH) after a 10-min occlusion of digital arteries. The frequency of flow oscillations in the second part of the PRH was established. Heart rate spectral analysis was performed based on the monitoring of the peripheral pulse frequency by means of the finapres device. In comparison to the other two groups of subjects, the group with a predisposition and a previous record of high blood pressure displayed a larger surface area in the low frequency band (0.05 to 0.15 Hz) of the heart rate variability power spectrum (the Bonferroni test, P < 0.05). As compared to subjects without predisposition, both groups of predisposed subjects exhibited higher frequency of flow oscillations in the second part of the PRH (the Bonferroni test, P < 0.05). Our results indicate that there could be a change in cutaneous microvascular reactivity of local (most probably myogenic) origin even in normotensive subjects with a predisposition to hypertension, whereas in normotensives with a predisposition and a previous record of high blood pressure there could be also a different cutaneous microvascular reactivity of central (nonvascular) origin.