Effect of chronic alcohol intake on muscle composition and metabolic balance of calcium and phosphate in rats

Chronic alcoholism is associated with abnormalities of serum and muscle mineral metabolism. Decreased muscle phosphate and magnesium and increased muscle calcium have been proposed as significant factors in the development of alcoholic myopathy. As the mechanisms producing these abnormalities remain unknown, we sought to reexamine these findings and investigate the extent to which the kidney and gastrointestinal tract contribute to their pathogenesis. Serum and muscle from rats receiving 20% of their caloric intake as ethyl alcohol were analyzed for PO₄, Ca, Mg, Na, and K at 0 and 20 wk and compared with isocalorically fed normals. In addition, individual metabolic balance studies were carried out over 72 h for Ca and PO₄ in normal and alcohol-fed rats. The results of serum and muscle analyses did not reveal any differences among the groups for any of the minerals examined. Metabolic balance studies demonstrated that despite a significantly lower Ca and PO₄ intake in the alcoholic rats (P < 0.003) net balance remained the same as in controls. This was due to the retention of a significantly larger proportion of the ingested mineral and was achieved for both means (P < 0.05) and PO₄ (P < 0.03) by ;means of greater gastrointestinal absorption and additionally for PO₄ by a reduction in renal excretion (P < 0.005). We conclude that in the rat chronic alcohol ingestion is not associated with abnormalities in serum or muscle mineral concentrations, normal adaptive mechanisms by the kidney and gastrointestinal tract compensate appropriately for differences in dietary Ca and PO₄, and the rat may not be a suitable species for the study of metabolic effects of chronic alcoholism.