Biochemistry of amphibian metamorphosis: effect of triiodothyronine, thyroxin, and dinitrophenol on the respiration of the tadpole.

A simple method involving the Warburg apparatus has been used for the study of the oxygen consumption of small and moderate sized tadpoles. Significant increases in the respiration of tadpoles were observed after small doses of 3,5,′-triiodothyronine, regardless of the unit of tissue used for the calculation. Thyroxin also increased tadpole oxygen consumption. However, it was not possible to establish whether or not spontaneous metamorphosis is accompanied by an increase in respiration. The tadpole gave a calorigenic response to 2,4-dinitrophenol whether administered by injection or by immersion. No significant increase was noted in succinoxidase activity after 3,5,′-triiodothyronine treatment. The possibility of the greater importance of alternative paths of oxidative metabolism in the tadpole is suggested.