PMID: 6536838Jan 1, 1984Paper

Potassium deficiency and cardiac function: experimental and clinical aspects

Magnesium
B Lüderitz

Abstract

Intra- and extracellular potassium and magnesium gradients in cellular membranes are essential factors of physiologic functions. Intestinal and renal loss of these ions cause predominantly a decrease in cellular potassium and magnesium by lowering the extra-cellular concentrations. In close connection with these changes, the permeability of cellular membranes for ions and, consequently, the excitability of skeletal and heart muscle cells are altered. Changes in the excitation, i.e. increased rising rate of the action potential and alterations of the refractory period, provoke cardiac arrhythmias. It is assumed that in contrast to chronic potassium deficiency the net changes which are caused by a reduction of extracellular potassium in acute deficiency states predispose to glycoside toxicity. These changes may therefore explain the clinical observation that acute hypokalemia is associated with a greater glycoside sensitivity than chronic potassium deficiency. Recent findings indicate that antikaliuretic substances can prevent the incidence of cardiac arrhythmias and may reduce glycoside sensitivity of the heart not only by antikaliuretic effects, but also by a possible direct action on the myocardium. Positive inotropic actions ...Continue Reading

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