Thyroxine-induced calorigenesis in frog liver: Insensitivity to ouabain

Abstract

Oxygen consumption of liver tissue from leopard frogs ( Rana pipiens complex) given five daily injections of thyroxine (2 μg/l0 g body wt) was 20% higher than the oxygen uptake by liver tissue from control animals. Since inhibition of Na +K + ATPase with ouabain (10 −3 M) had no detectable effect on oxygen consumption of liver tissue from either hyperthyroid or control frogs, it seems that the contribution of active Na + transport to the overall metabolism of liver tissue was too small to be detected by the method of respirometry used in this study. Thus, the thyroxine-induced calorigenesis manifest by liver of leopard frogs cannot be attributed to stimulation of the “sodium pump.”