In vitro synthesis of C¹⁴-corticotropin by isolated rat anterior pituitary: effect of adrenalectomy

¹ Department of Physiology, University of Chicago, Chicago, Illinois

A method is described for the measurement of C¹⁴-corticotropin synthesis by isolated rat anterior pituitary tissue. Intact pituitary glands were incubated with C¹⁴-phenylalanine; carrier anterior pituitary powder (porcine) was added and corticotropin extracted with hot glacial acetic acid and purified with oxycellulose. The oxycellulose concentrate contained corticotropin (as measured by its ability to cause enlargement of the adrenal gland of hypophysectomized rats) and was free of C¹⁴-phenylalanine; on dialysis the radioactivity in the oxycellulose concentrate behaved like purified corticotropin. The rate of C¹⁴-corticotropin synthesis by isolated rat anterior pituitary was linear for 4 hr and was increased in pituitaries from adrenalectomized rats. Adrenalectomy did not increase amino acid incorporation into total protein of anterior pituitary; the effect of adrenalectomy was only apparent when pituitary protein was fractionated and oxycellulose concentrates prepared, which is for a specific biological effect of adrenalectomy on corticotropin synthesis.