Changes in Mg+2-ATPase and taurine levels in Mg+2- deficient rats.

Tissue levels of Mg+2-ATPase and taurine were measured in rats fed Mg+2-deficient diets. Serum and urinary Mg+2 levels of rats fed the deficient diet were 50% below the control levels by day 10 on diet. The Mg+2-deficient rats showed a significant decrease in intestinal Mg+2-ATPase relative to the controls, despite having no significant decrease in intestinal Mg+2 levels. The effect of the Mg+2 deficiency on the distribution of subcutaneously injected 1,2-[14C]taurine in the skeletal muscle cytosol and organelles was measured. The cytosolic fraction contained 90% of the [14C]taurine, while the nuclear fraction contained 98% of the noncytosolic [14C]taurine. The skeletal muscle of Mg+2-deficient rats contained 14, 14, 81 and 53% more [14C]taurine than the control muscle at 1, 16, 24 and 48 hours after injection, respectively. There was 21, 60, 97 and 350% more [14C]taurine associated with the nuclear fraction of the muscle from Mg+2-deficient rats at the same sampling periods.