Effect of insulin on the phosphorus-32 mononucleotide and phosphocreatine labelling in the isolated diaphragm of the normal, the hypophysectomized, and the hypophysectomized growth-hormone treated rat

• Published in: General and comparative endocrinology Vol. 2; no. 4; pp. 369 - 384
• Main Authors: Clauser, H., Volfin, P., Eboué-Bonis, D.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.01.1962
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1016/0016-6480(62)90053-9

The rate of penetration of inorganic phosphate (Na 2H 32PO 4) and the turnover of the acid-soluble organic phosphates, including free nucleotides, has been determined on the isolated diaphragm of the normal, the hypophysectomized and the hypophysectomized growth-hormone treated rat. The influence of insulin on this turnover has been studied in the presence and in the absence of glucose. Insulin has no effect on the rate of penetration of inorganic phosphate into the intracellular space, but promotes, in every case, a striking enhancement of the labelling of organic phosphates, both in the presence and in the absence of extracellular glucose. Insulin specifically increases the labelling of the second phosphate of ATP both in the normal diaphragm and in the diaphragm of hypophysectomized rats, when no substrate is added to the incubation medium. With the diaphragm of the hypophysectomized rat, in the presence of glucose, and with the diaphragm of the hypophysectomized growth-hormone treated rat, the labelling of the terminal phosphate of ATP is specifically increased by insulin. Significant effects of insulin and growth hormone on uridine- and guanosine-nucleotide labelling are also observed. The significance of these results is discussed with respect to the metabolic patterns, which are obtained in the isolated diaphragm under various physiological conditions.