Generation of somatomedin activity in response to growth hormone and insulin from isolated perfused livers of normal and protein-malnourished rats.

The generation of somatomedin activity by isolated perfused livers was examined in protein-malnourished (4% casein diet) and well-nourished (controls, 20% casein diet) rats. There was significantly less somatomedin activity (measured by the porcine costal cartilage bioassay), after perfusion for 2 h, in the perfusates from the livers of malnourished rats both in hormone-free perfusates and perfusates containing hormones (10 microgram GH/ml, 1000 microunits insulin/ml or a combination of the two). A reduction in the somatomedin activity generated by the liver may be the mechanism responsible for the low serum level of somatomedin (in spite of raised or normal levels of growth hormone) in human or experimental protein malnutrition.