Decreased venous distensibility in borderline hypertension.

SUMMARY There are abnormalities in renous structure and function in animal models of hypertension. In humans with borderline hypertension, there is a redistribution of blood from the periphery to the central circulation that may be produced in part by a decrease in peripheral Tenons distensibility. In this study we used a water-filled pletbysmograph to determine forearm renous distensibility in nine young men with borderline hypertension and nine normotensive control subjects. The venous pressure-volume curve in men with borderline hypertension as compared to that in normotensive men was shifted toward the pressure axis (p < 0.05). This indicates that venous distensibility was significantly decreased in borderline hypertension. Pbentolamlne, 1 mg I.V. for 5 minutes, increased venous distensibility slightly but significantly (p < 0.05) in borderline hypertensive men, but not in normotensive men. Thus, decreased venous distensibility in borderline hypertensive subjects was due in part to a-adrenergic renoconstriction. Venous distensibility after phentolamine was less in borderline hypertensive men than in normotensive men (p < 0.05). This finding suggests that most of the decrease in venous distensibility in borderline hypertension resulted from non-adrenergic mechanisms. Thus, there is a decrease in venous distensibility in young men with borderline hypertension that is related partly to adrenergic mechanisms, but also involves other factors, perhaps including structural changes in veins.