The effect of plasma from patients with essential hypertension on the contractility of human arteries.

The effect of plasma from patients with essential hypertension and from normotensive subjects on the contractile response to noradrenaline and potassium chloride has been investigated using human isolated arteries. After incubation with plasma from normotensive subjects, there was no change in the contractile response to either noradrenaline (-3.0 +/- 5.4%; P = NS) or potassium chloride (3.2 +/- 3.0%; P = NS). After incubation with plasma from patients with essential hypertension, the contractile response to noradrenaline was significantly increased (24.8 +/- 9.8%; P less than 0.01) whereas that to potassium chloride did not change (-0.4 +/- 3.7%; P = NS). The change in the contractile response to noradrenaline in the presence of plasma from hypertensive patients was significantly higher than that obtained in the presence of plasma from normotensive subjects (P less than 0.03) whereas that to potassium chloride was not different between groups (P = NS). These findings suggest that the increased vascular reactivity of human arteries in the presence of hypertensive plasma could be related to specific mechanisms requiring receptor-mediated activation of the vascular smooth muscle cell.