Hypobaric Hypoxia Reduces GLUT2 Transporter Content in Rat Jejunum more than in Ileum

Abstract

To define some of the specific cellular effects of chronic hypoxia on the small intestine, we measured the concentration of glucose transporter 2 (GLUT2) at two sites, the jejunum and ileum. Wister rats were subjected to 21-day normoxia (n=6) or to continuous 21-day hypobaric hypoxia approximately 0.5 ATM (n=5). Western blot analysis was performed and the abundance of GLUT2 protein was quantified as relative densitometric units and normalized to actin. GLUT2 content was similar in the jejunum and ileum under normoxic (jejunum = 0.65±0.13 mean±SD; ileum = 0.56±0.22 OD; mean difference 0.09, p=0.09) and hypoxic conditions (jejunum=0.56±0.14 OD mean±SD; ileum = 0.58±0.16; mean difference −0.01, p =0.42). GLUT2 decreased by 14% of the mean normoxic jejunal levels whereas ileal GLUT2 was slightly increased. A maximum decline in weight of 15% occurred at day 4 followed by a blunted rate of weight gain for rats in the hypoxic group. Thus, sustained exposure to hypobaric hypoxia reduced the availability of GLUT2 for glucose transport in the jejunum. Regulating small intestinal content of glucose transporters may be an important mechanism for tissue adaptation to chronic hypoxia. This finding provides initial insight into hypoxic tolerance of the gut to chronic hypobaric hypoxic exposure.