Glucose absorption by in vitro perfused ileum of the fetal rat.

In vitro intraluminal perfusion of the fetal rat ileum at 19 and 20 days of gestation was employed to measure the rate of glucose absorption and the unidirectional fluxes of 3-O-methylglucose (3-O-MG). Fetal ileum was mounted on pipettes within an oxygenated bath and perfused with a solution containing glucose or 3-O-MG and polyethylene glycol with average molecular weight of 4,000 (PEG) as a marker substance. We verified that the PEG was not transported and did not diffuse across the fetal ileum. Scanning and electron microscopy before and after perfusion demonstrated preservation of mucosal anatomy. The rate of glucose absorption was 200 +/- 17 mumol.h-1.g-1 at 19 days and increased significantly to 378 +/- 12 mumol.h-1.g-1 at 20 days. The absence of sodium abolished this process. The flux of 3-O-MG from lumen to bath was 88 +/- 10 mumol.h-1.g-1 at 19 days and 160 +/- 16 mumol.h-1.g-1 at 20 days. Bath-to-lumen flux was -17 +/- 2 mumol.h-1.g-1 and did not vary with age. Active, rapidly developing transport of glucose and 3-O-MG is demonstrated by in vitro luminal perfusion of the fetal rat ileum at 19 days.