Magnesium distribution in rats after maximal exercise in air and under hypoxic conditions.

Variations in serum levels and distribution of Mg in the heart, gastrocnemius, liver and kidney in rats were studied after exercise to exhaustion in air (normoxia) and during hypoxia (FIO2 = 0.10). After exercise serum Mg concentrations increased significantly in air, but not during hypoxia. At rest, they increased significantly during hypoxia. In air, increases in Mg in the gastrocnemius and liver were found after exercise. At rest in hypoxia, Mg was reduced in heart, liver and kidney. After exercise in hypoxia, Mg was decreased in heart, gastrocnemius and liver, the greatest decrease occurring in the gastrocnemius, with a relative increase in kidney. Exercise and hypoxia both affect magnesium homeostasis.