A biochemical and ultrastructural study of skeletal muscle from rats fed a magnesium-deficient diet

In order to study changes in skeletal muscle during a magnesium deficiency, serum and muscle tissues were collected from male Sprague-Dawley rats fed either a control or magnesium-deficient diet. The rats were killed on days 7, 10, 14, 17, 19, 21 and 26 of the experiment. Ion concentrations in serum and muscle were determined by atomic absorption spectrophotometry, taurine concentrations of serum and muscle were determined by the Pentz method, and ultrastructural changes in skeletal muscle were detected with the use of the transmission electron microscope. The results indicated an increase in serum taurine which preceded an increase in muscle taurine concentration in rats fed a magnesium-deficient diet. The electron micrographs showed a swelling of mitochondria on day 14 of the deficiency and a total disorganization of the sarcoplasmic reticulum by day 26. In conclusion, in skeletal muscle from rats fed a magnesium-deficient diet, major ultrastructural changes apparently occur after the serum magnesium concentration is reduced and about the same time as muscle taurine concentration becomes elevated. The changes may be initiated by alterations in membrane permeability which may be influenced by taurine, since taurine has been shown to influence ion movement across membranes or membrane stability.