[Liver mitochondrial phospholipase activation in hyperthyroid rabbits]

Mitochondria obtained from hyperthyroid rabbit liver contained an approximately 4-fold greater amount of free fatty acids (FFA) than preparations from the control animals. The temperature dependence of FFA accumulation (29--38 degrees C) showed that the activation energy of mitochondrial lipid hydrolysis for control and experimental animals was 7 kcal/mole and 29 kcal/mole, respectively. The mitochondria were kept at 3 degrees C for 48 h. During this period there was an accumulation of fatty acids. The rate of the process in the mitochondria of hyperthyroid animals was several times than that in the control ones. This indicates the activation of mitochondrial phospholipase by the liver in hyperthyrosis. The increased mitochondrial phospholipase activity seen in hyperthyrosis is assumed to be determined by changes in the physical properties of lipid membranes.