There is a predominance of sympathetic over parasympathetic activity in patients with developed essential hypertension. We were interested in knowing whether reactivity of microvessels is different in young healthy adults with family history of hypertension and those without.

Experiments were performed on 38 healthy adults 19–24 years old. We measured ECG, arterial blood pressure and laser-Doppler (LD) flux in the skin of the fingertips first at rest in the supine position, then 3 minutes while having legs passively raised and finally 3 minutes with having them put down to supine position again. Subjects were divided in two groups: those that had hypertension in family history (N=17) and those that had not (N=21). There were no differences in systolic and diastolic blood pressure or in RR interval between the two groups. The study has ethical approval and the consent has been obtained from each subject.

The two groups of subjects showed significant difference in the LD flux while having legs lowered down again. Those without hypertension in family history exhibited greater LD flux than at rest (112.5±10%), while those with hypertension in family history exhibited smaller LD flux than at rest (83.6±8%) (t-test, p<0.05).

During physiological manoeuvre of lifting and lowering the legs in supine position young healthy adults show difference in the reactivity of skin vessels. It seems that sympathetic vasomotor action is pronounced or prolonged in subjects with hypertension in family history.