Effect of cortisone on aspartate and alanine aminotransferases in a desert lizard.

1. Liver and serum aspartate aminotransferase (GOT) and alanine aminotransferase (GPT) activities were measured in a hibernating desert lizard, Uromastix hardwickii. The levels of both enzymes were found to be lower in hibernation than during the active period, particularly in the liver. 2. After intramuscular injection of 2 mg of cortisone acetate there was a rapid rise in the levels of these enzymes with a peak of 18 hours (GOT) and 12 hours (GPT). 3. The response of both enzymes to cortisone was much greater during the active period than during hibernation. 4. GOT showed a much more rapid and greater response to cortisone than GPT. This is in contrast to the response of rat liver where GPT is more responsive to this hormone. 5. These studies indicate that the transferase enzymes of this lizard differ from those of the rat in their sensitivity and time of response to cortisone.