ENERGY-STATE OF RAT-LIVER IN DYNAMICS OF COLD-ACCLIMATION

The energy state of the rat liver has been studied at various times of long-term cold acclimation (5 degrees C). On day 10 of cold exposure the energy state of the liver is characterized by low levels of ATP an d adenine nucleotide pool and by low phosphorylation potential and ''e nergy charge'' (state 2). In mitochondria the respiratory control and transmembrane potential decrease, and ion conduction of inner membrane increases. On days 10-15 of cold exposure, when the body temperature is lowered, the liver presumably becomes actively involved in thermal stabilization. Cold exposure for 35-42 days increases the rate of elec tron transport in metabolic state 3, respiratory control, and energiza tion of liver mitochondria, thus providing ATP content and total adeni ne nucleotide pool in the tissue at the control level. However, this d oes not seem to compensate completely for the energy consumption since phosphorylation potential and ''energy charge'' of the liver are decr eased.