Oxygen Consumption of Normal and Thyroxin-Stimulated Rana pipiens Skin

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Abstract
The metabolism of isolated Rana pipiens skin was studied. All measurements of metabolism were obtained by the direct method of Warburg. The metabolic rate of skin from 129 normal tadpoles, juveniles, and adults showed a clear trend of increase to a max. at metamorphic climax and a later decrease to the adult level. 53 animals were placed into 110,000,000 thyroxin soln. for 48 hrs. Metabolic rate of their skins at stages IX through XIV was compared with that of 53 normal skins for these stages. In all stages, considered together, there was a significantly higher metabolic rate for skin of exptl. animals as compared with skin of the normal control animals. Effect of the thyroxin treatment was not significantly different from stage to stage. 5 pellets of 20% thyroxin in cholesterol were implanted subcut. into the right side of each of 14 pairs of animals. Cholesterol control pellets were implanted on the left side. After 72 hrs., at stages IX through XIV, the metabolic rate on the right side was found to be significantly higher than that of the left side. This showed that the metabolic rate of the entire skin is dependent not only on the thyroxin concn. in the body as a whole but was also affected locally by a spatially restricted treatment with thyroxin. Metabolic response to thyroxin treatment preceded morph. response.