Hormonal effects on liver and kidney cytoplasm.

Abstract

SUMMARY 1. Differential centrifugation, in 0·25 m sucrose solution, has been performed with rat liver and kidney tissue to ascertain whether the yield and composition of the cytoplasmic fractions (mitochondrial, microsome and supernatant fractions) depend on the hormonal status of the animal. 2. After hypophysectomy the ribonucleic acid (RNA) of the mitochondrial fraction from liver underwent a decrease (in terms of body weight) which was sufficient to account for the fall in the RNA of the liver as a whole. There was also a decrease in the yield of the mitochondrial fraction. Administration of pituitary growth hormone (GH) to hypophysectomized rats not only restored to normal the amount of RNA in the mitochondrial fraction and the yield of that fraction, but also led to an apparent shift of RNA from the microsome fraction to the supernatant fraction. A further change observed after hypophysectomy, whether or not GH had been given, was a rise in the yield of the microsome fraction. Hypophysectomized rats given thyrotrophin (TSH) did not show significant cytoplasmic changes as found with untreated hypophysectomized rats, but it was not possible to conclude that TSH had actually reversed the effects of hypophysectomy. 3. Castrated rats showed no abnormalities in the yields of the liver cytoplasmic fractions or in the concentration of RNA in the fractions. Alloxan-diabetic rats showed a rise in the yield of the supernatant fraction from liver. 4. Untreated adrenalectomized rats showed a rise in liver deoxyribonucleic acid, a fall in the yield of the liver mitochondrial fraction, but not in the amount of RNA in that fraction, and a rise in the amount of RNA in the supernatant fraction. Replacement therapy with various adrenocorticoids was attempted, with only partial success. 5. In contrast with the RNA content, the phospholipid content of the liver cytoplasmic fractions was not, in general, dependent on hormonal status. 6. Determinations of the yield and composition (RNA and phospholipid) of the cytoplasmic fractions from kidney disclosed certain hormonal effects, differing from those observed with liver; for example, the kidneys from hypophysectomized rats furnished microsome fractions in lowered yield but with an increased concentration of RNA.