[Effect of thyroxin on the functional state of the respiratory chain in liver mitochondria of the carp Cyprinus carpio during acclimatization to changes in water temperature].

It has been demonstrated that oxidative phosphorylation in liver mitochondria of the carps which were kept within a week at 5 and 25 degrees C remains unaffected by the addition of 0.5 micron thyroxin to the incubation medium. Addition of thyroxin (0.5 micron) to mitochondrial suspension prepared from the liver of carps acclimated within a week at 20 and especially 25 degrees C, resulted in uncoupling of respiration and phosphorylation. Daily injections of thyroxin within a week (2 mu kg per 1 g of body weight) to carps at 20 and 25 degrees C resulted in the increase of the rate of non-phosphorylating oxidation and the decrease of oxidative phosphorylation in liver mitochondria. The increase of temperature of water from 5 to 30 degrees C decreases triiodthyronine content of the blood serum in the carp.