Effect of ACTH and Insulin on AIB Accumulation in Diaphragm Muscle and Adrenal in vivo.

Abstract

Distribution of the amino acid analogue, a-aminoisobutyrate (AIB), between tissues and plasma was examined in adrenal and diaphragm of functionally nephrectomized rats before and after hypophysectomy over a wide range of plasma AIB concentrations, and also in hypophysectomized, nephrectomized rats 90-100 min. after receiving exogenous ACTH, insulin, corticosterone, or growth hormone. Hypophysectomy causes a decline in the accumulation of AIB in both diaphragm muscle and adrenal. This decline is most pronounced at lower plasma AIB concentrations (1-10ug/ml), since AIB distribution falls progressively at higher AIB levels in these tissues of intact, but not hypophysectomized rats. Either corticotropin A or insulin significantly increase AIB accumulation to an equivalent extent in adrenal of hypophysectomized rats; both hormones also increase AIB uptake in diaphragm muscle, but insulin is much more effective in this tissue. The combined influence of these hormones on both tissues is greater than either alone.