Glucose transport in adipocytes and its control by growth hormone in vivo.

Previous results showed maximally enhanced basal glucose transport in adipocytes of hypophysectomized rats and restoration to normal after human growth hormone (hGH) administration. The data suggested a hGH-dependent "limiting factor" for glucose transport in the adipocyte membrane, which is acutely inhibited by insulin resulting in enhanced glucose transport. In this study the effect of hGH was investigated with respect to dose and time dependence. hGH was administered by continuous infusion from subcutaneously implanted Alzet minipumps. A significant decrease of basal glucose transport was obtained at the lowest hGH dose of 50 mU/day for 6 days. This effect of hGH was strictly correlated to the effects on growth (tibial epiphyseal width, DNA synthesis, body weight, serum level of insulin-like growth factor). The effect of hGH on basal glucose transport was already observed after 12 h of infusion, and it increased to a maximum after 3 days. The data support the concept that GH regulates the glucose transport system in adipose tissue in vivo.