NO EVIDENCE FOR EXPRESSION OF THE INSULIN-REGULATABLE GLUCOSE TRANSPORTER IN ENDOTHELIAL-CELLS

A MAJOR effect of insulin is to increase glucose transport in muscle and fat1,2. A family of genes encoding distinct mammalian glucose transporters has recently been elucidated3-9. One of these, the insulin-regulatable glucose transporter (IRGT)3,10, is primarily expressed in muscle and fat, tissues that exhibit insulin-dependent glucose transport. Insulin promotes glucose transport in these tissues by stimulating movement of the glucose transporter from an intracellular location to the plasma membrane3,10-14. Recent studies15, however, suggest that an additional effect of insulin in these tissues may be the facilitation of glucose transport, presumably across capillary endothelium. This hypothesis is based on the localization of the IRGT in endothelial cells specific to muscle and adipose tissue. We report here, however, on morphological and biochemical studies using several different IRGT-specific antibodies in which we could not reproduce these results. © 1990 Nature Publishing Group.