Magnesium Deficiency in the Cebus Monkey

Abstract

Purified diets containing cholesterol and deficient or adequate in magnesium were fed to young growing Cebus (fatuella) monkeys. Diet-induced magnesium deficiency resulted in weight loss, hyperirritability, and in several monkeys, convulsions. In addition to the expected hypomagnesemia, deficient animals also had decreased serum potassium levels. However, after several weeks on diet, the electrocardiogram of deficient animals showed significant changes consisting primarily of S-T segment depression and peaking of the T wave; changes usually seen in hyperkalemic states. Prior to sacrificing the animals, the tolerance to K-strophanthidin, a cardiac glycoside, was ascertained in both deficient and control animals. The cardiac glycoside was administered slowly by the intravenous route to anesthetized monkeys and the appearance of four consecutive ventricular premature contractions in the electrocardiogram was taken as the end-point. Deficient animals required approximately one-half the dose administered to control monkeys to develop extrasystoles. The histopathology consisted of marked vascular sudanophilic deposits and dense fibrous connective tissue plaques in the ascending and descending aorta of deficient monkeys. Control animals showed little, if any, vascular sudanophilia. The serum cholesterol concentration increased significantly in the deficient group while the rise seen in control monkeys lacked statistical significance.