Swelling of Heart and Liver Mitochondria from Magnesium Deficient Rats and Its Reversal.

Swelling of mitochondria isolated from the heart and liver of rats fed a magnesium deficient diet was examined photometrically and by electron microscopy. A rapid swelling of heart and liver mitochondria was produced in rats fed a magnesium deficient diet for 10 days, whereas there was no significant decrease in the magnesium content of the mitochondria. A morphological swelling of heart mitochondria of rats fed a magnesium deficient diet was also demonstrated. Addition of thyroxine produced a slight increment or none in the rate of swelling of mitochondria isolated from deficient rats. ATP reversed swelling of heart and liver mitochondria from deficient rats; EDTA, however, prevented only the swelling of liver mitochondria. Mitochondria of heart contained twice the amount of magnesium found in liver mitochondria. The mechanism of decrease of P/O ratio of mitochondria from magnesium deficient rats and the physiological significance of magnesium deficiency induced swelling of mitochondria, were discussed.