Abnormal magnesium metabolism in two rat models of genetic hypertension

Magnesium concentrations in erythrocyte ghosts and arterial tissue of male, spontaneously hypertensive rats (SHR) were significantly less than in these tissues of male normotensive controls (Wistar-Kyoto; WKY) of the same age, which were also fed rat chow and tap water. The magnesium concentration in SHR erythrocyte ghosts was increased to the control value by incubating SHR erythrocytes with WKY blood plasma; SHR plasma did not affect the magnesium concentration in WKY erythrocyte ghosts. The magnesium concentrations in erythrocyte ghosts, aortas, and mesenteric arteries from female salt-sensitive (SS/JR) and salt-resistant (SR/JR) Dahl-derived rats, both maintained ad libitum on laboratory rat chow and either tap water or 0.9% NaCl, were not different but were significantly less than those of Sprague-Dawley rats considered as controls. While the ingestion of 0.9% NaCl had no effect on the magnesium concentrations measured in these animals, it caused the salt-sensitive rats to become severely hypertensive. It is evident from these observations that the decreased binding of magnesium to the plasma membrane of cells may be an inheritable metabolic defect that may be associated with the development of hypertension. However, in those instances of hypertension in which this defect occurs, it appears to be a contributing cause of the hypertension; by itself the defect is not a cause of hypertension.