Growth hormone covalently bound to Sepharose. II. Study of the biological activity of a growth hormone-Sepharose complex in adipose tissue and diaphragm muscle

Bovine growth hormone (bGH) covalently bound to Sepharose was tested for biological activity in vitro on diaphragm muscle and adipose tissue from hypophysectomized rats. Only under special conditions did bGH—Sepharose seem to stimulate a—aminoisobutyric acid (AIB) transport, the incorporation of leucine into protein, or glucose utilization. Exposure of adipose tissue to GH—Sepharose, like exposure to free GH, also appeared to make the tissue refractory to subsequent stimulation by free bGH. It is doubtful, however, that GH produced these changes while still bound to the Sepharose, since material with GH—like activity was found in the medium after removal of the bGH—Sepharose by centrifugation. This active material appeared only when the incubation medium contained tissue or had been previously exposed to tissue. These findings are consistent with the hypothesis that the tissues release some substance which in turn releases active material, perhaps GH itself, from the GH—Sepharose complex. Endocrinology 92...