Calf vascular resistance in middle-aged subjects with mild chronic hypertension

To ascertain the effect of elevated blood pressure in adolescence and its 28-year persistence on the arterial haemodynamics in the legs, calf blood flow during dilatation was determined plethysmographically in 52 middle-aged subjects. Blood pressure was measured by auscultation on the arm at rest and during peak hyperaemia. Local vascular resistance during dilatation was calculated from the men blood pressure and maximal flow and was expressed in resistance units. The subjects were divided into 3 groups according to the magnitude of blood pressure (hypertension, borderline hypertension and normotension). Controls comprised 36 normotensive subjects of the same age. The results showed identical values of calf resistance at maximal dilatation in all three groups (hypertension: 2.65 +/- 0.86, borderline hypertension: 2.76 +/- 0.73, normotension: 2.43 +/- 0.33), which did not differ from the control value (2.41 +/- 0.50). The individual values of resistance during dilatation exceeded the upper limit of normality only in 7 of all investigated subjects. It is therefore supposed that in addition to elevated blood pressure other factors inducing the development of structural auto-regulation in the skeletal muscle vascular bed of the lower extremities must be involved.