Male young and adult rats were injected with thyroxin, hydrocortisone and puromycin. Monoamine oxidase (MAO) activity was studied in liver, brain, kidney, and heart with L-tryptamine-2-14C as substrate. After thyroxin treatment, heart MAO increased in young animals but decreased in adult animals. Thyroxin decreased liver MAO in adult animals. Brain MAO remained constant in all experiments, whereas kidney MAO showed a slight decrease after thyroxin injection. In young rats, puromycin did not prevent the increase in heart MAO caused by thyroxin injection. Hydrocortisone did not enhance MAO activity in liver, brain and heart. Of all organs studied, only the heart showed a marked increase of MAO with age. In female rats, thyroxin has little effect on brain and liver MAO, whereas it increases MAO activity in the heart of young and adult animals by 67% and 32% respectively. Adult female rats have twice as much heart MAO as males.
Under our experimental conditions, water represented 72% of the fat-free body mass. This constant was found to be completely independent of the magnitude of the fat depots. Consideration of the composition of various samples of adipose tissue suggests that the water to fat-free dry matter ratio is the same as in the body as a whole or that any "excess" water contributed by adipose tissue is so small in absolute amounts as to leave the global ratio essentially undisturbed. Rats exposed to cold had to draw on their fat stores during the first month of exposure but later replenished their energy reserves. The water to fat-free dry matter ratio was not affected.
Normal and cancerous mice were injected with 1-aminocyclopentane C14-carboxylic acid and the distribution of the drug in the animals was studied by autoradiography. In normal mice, the amino acid is concentrated selectively by the pancreas and the bone marrow. In cancerous mice (Ehrlich ascites tumor and sarcoma-180), the tumor cells also intensively accumulate the amino acid.
Under our experimental conditions, water represented 72% of the fat-free body mass. This constant was found to be completely independent of the magnitude of the fat depots. Consideration of the composition of various samples of adipose tissue suggests that the water to fat-free dry matter ratio is the same as in the body as a whole or that any "excess" water contributed by adipose tissue is so small in absolute amounts as to leave the global ratio essentially undisturbed. Rats exposed to cold had to draw on their fat stores during the first month of exposure but later replenished their energy reserves. The water to fat-free dry matter ratio was not affected.
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