[Mechanism of the increase in peripheral vascular resistance in hypertension]

To elucidate the mechanisms determining peripheral vascular resistance in arterial hypertension the circulation in the leg was studied by venous occlusion plethysmography in 41 hypertensive patients and 11 normotensive controls. It was found that vascular resistance in the leg both at rest and during maximal vasodilatation were within the normal limits in labile and mild hypertension, but it was significantly raised in established, malignant and refractory hypertension. The increased Rmin strongly suggests structurally narrowed lumina, but not enhanced vasoconstriction of the neurohumoral origin. Moreover, vascular smooth muscle activity at rest was not increased in absolute values in hypertensive patients though it may be considered as inappropriately "high" in relation to the altered vascular design. It was concluded, that at least in the vascular bed of the leg a rise in peripheral resistance is caused by structural changes of the resistance vessels along with unchanged contractile activity of the vascular smooth muscles.