Anterior Lobe,the Thyroid Stimulator,V. Basal Metabolism.

Abstract

If anterior lobe of the hypophysis is the activator of the thyroid gland, it should raise the basal metabolism. We made 96 Winkler-tests to determine the oxygen consumption of larvae of Ambystoma tigrinum, 37 tests of normal control larvae, 33 tests of larvae injected with an extract of bovine anterior lobe powder, which was prepared in our own laboratory, 16 tests of larvae which had been fed this powder, 7 tests of larvae which were fed Armour's anterior lobe powder and 3 tests of larvae fed posterior lobe powder prepared in our own laboratory.

Larvae of the Utah axolotl were tested without anesthesia. The average oxygen consumption of the injected animals was found 30% higher than that of the controls.

Larvae of the eastern race of Ambystoma tigrinum † were tested without anesthesia. The average oxygen consumption of the injected animals was 51% higher than that of the controls.

Larvae of the eastern race of A. tigrinum were tested in chloretone anesthesia. The average oxygen consumption of the injected animals was 114% higher than that of the controls.

Feeding of the anterior or posterior lobe powders did not change the oxygen consumption.

We expressed oxygen consumption in cc. of oxygen per hour and gram animal weight. But metabolism changes parallel with surface and not with weight. Of 2 species having actually the same oxygen consumption, but different size, the larger one may incorrectly appear to have the lower oxygen consumption, if oxygen consumption is calculated per gram weight. In our experiments all animals were of the same species and, in 2 experiments, of the same brood. The differences in oxygen consumption between the controls and the injected experimentals were considerable and present even if controls and experimentals were of the same size and weight as was often the case.