Abnormal Biochemistry of Vascular Smooth Muscle Plasma Membrane Isolated from Hypertensive Rats

We have demonstrated that the mesenteric arteries of rats with either genetic hypertension or experimental hypertension induced by dexoycorticosterone have similar biochemical alterations which were manifested by (a) increased amount of total wet weight of arteries as well as total protein content of isolated arterial plasma membranes, (b) increased alkaline phosphatase activities in the plasma membranes of arterial smooth muscle, and (c) decreased ATP-dependent transport of calcium by the arterial plasma membranes. The observed abnormal biochemical properties cannot be attributed to the use of different strains of normotensive control rats in the case of genetic hypertension. Deoxycorticosterone treatment alone slightly enhanced alkaline phosphatase activity but did not alter calcium accumulation, weight or protein content of plasma membranes from arterial smooth muscle. The results suggest that abnormal biochemistry of the plasma membrane isolated from small arteries of hypertensive animals, which appears to involve a defect of calcium regulation across the vascular plasma membrane, is probably associated with the pathogenesis of hypertension. ACKNOWLEDGMENT We thank Ms. K. Wong for her excellent technical assistance.