Isolation from subcellular preparation of a mediator of hypoglycaemic hGH peptides.

This study demonstrated the release into the incubation medium of a cellular mediator from isolated fat adipocytes and hepatocytes after treatment with the hypoglycaemic fragment of human growth hormone, hGH 6-13. The activity of the putative mediator observed in the cell "ghosts" of both liver and rat cells suggests that the active component is likely to be derived from plasma membranes and has an ubiquitous cellular distribution. The hGH fragment-induced release of the mediator from plasma membranes depends upon the physiological status of the animals. Liver plasma membranes of starved rats yield significantly higher levels of the cellular mediator in response to treatment with hGH 6-13. The studies of the physiological factors influencing the release of the material from cellular systems clearly enhance the production of adequate amounts of the cellular mediator for molecular characterization. The precise chemical nature and the physiological role of the hGH cellular mediator are currently unknown.