Interactions of Mg and K on blood vessels--aspects in view of hypertension. Review of present status and new findings. Altura BM, Altura BT.

Abstract

Considerable experimental as well as clinical evidence has now accumulated to indicate that Mg2+ and K+ deficiencies have probably been overlooked as important causal factors in the etiology of hypertensive disease. Mg2+ ions are important for the regulation of Na+ and K+ transport across cell membranes, including those found
in cardiac and vascular smooth muscle cells. Mg2+ activates a Na+-K+-ATPase pump which in turn plays a major role in regulating Na+-K+ transport. Loss of cellular Mg2+ results in the loss of critically important phosphagens: Mg ATP and creatine phosphate. Thus, under conditions where cellular Mg2+ is depleted (e.g. hypoxia, anoxia, ischemia, Mg deficiency, errors in Mg metabolism and/or binding, and transport), the Na+-K+ pump and phosphagen stores will be compromised, leading to alterations in resting membranes (e.g. membrane depolarization). Cellular Mg2+ depletion has been found to result in concomitant depletion of K+ in a number of cells, including cardiac and vascular muscles. Myocardial and vascular injury thus results in an uptake of Na+ and Ca2+, Mg2+ and K+ being lost first. The available evidence indicates that Mg2+ is important in the control of arteriolar tone and blood pressure, primarily via the regulation of vascular membrane Mg2+-Ca2+ exchange sites. A reduction in extracellular Mg2+ (or K+) can produce hypertension, vasospasm and potentiation of vasoconstrictor agents by allowing excess entry of Ca2+, concomitantly the potency of vasodilators is reduced. Alterations in vascular membrane Mg2+ result in 'leaky' arterial and arteriolar membranes thus contributing to the cellular reduction in K+ and the gain of Ca2+ and Na+. These factors seem all-important in the production and etiology of hypertension. Both clinical and experimental forms of hypertension are associated with tissue and plasma deficits of Mg2+. The arterial blood pressure elevation appears to be inversely related to the level of ionized intracellular and plasma Mg2+. Source: http://www.ncbi.nlm.nih.gov/pubmed/6399341

Burton M. Altura, Professor of Medicine, Ph.D. (1964, New York University School of Medicine) http://www.downstate.edu/pharmacology/faculty/altura_burt.html Bella T. Altura, Professor of Physiology and Pharmacology,Ph.D. (1968, City University of New York) http://www.downstate.edu/pharmacology/faculty/altura_bella.html