Shinichiro Torii

Swelling of heart and liver mitochondria from magnesium deficient rats and its reversal.

Summary 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.

A Study of Lipoprotein Lipase Produced by Perfusion of Isolated Rabbit Heart with Heparin.

Summary With a perfused, isolated rabbit heart LPL activity appeared in the perfusion solution of bicarbonate buffer in the presence of 5 mg % heparin and 5 to 10% serum. However, under the same conditions, LPL did not appear with phosphate buffer. The LPL produced was inhibited by protamine sulfate, CaCl2 and NaCl. Optimum pH of enzymatic activity was at pH 8.2, and 80% of the activity was lost by heating at 50°C for 2 min and 70°C for 30 sec. After perfusion, LPL activity in the heart disappeared. Total activity appearing in the circulating solution was nearly equal to total activity of heart tissue which was extractable with ammonium buffer solution.