AJP - Gastrointestinal and Liver Physiology, Vol 250, Issue 2 221-G226, Copyright © 1986 by American Physiological Society
Glucose-coupled sodium absorption in the developing rat colon
G. D. Potter and S. M. Burlingame
The developing mammalian colon is lined by villi and is capable of glucose
and amino acid absorption at birth in the rat. Neither the point at which
this capacity is lost nor the effect of the capacity for glucose transport
on Na absorption has been studied. We have now applied a system for
perfusion of the lumen of in vitro segments of colon from 20-day-old fetal
rats, and pups between 6 and 8 days old, to measure Na transport and
transepithelial potential difference (PD). The lumens of colons from
animals at both ages were perfused with solutions containing glucose or
mannitol and 22Na. Net Na transport was 164 +/- 37 mu eq X h-1 X g dry
weight tissue perfused-1, as determined by the difference between
lumen-to-bath and bath-to-lumen flux in fetal rat colons at day 20. Glucose
increased the lumen-to-bath flux by 90 +/- 35 mu eq X h-1 X g-1. PD was
immediately increased from -1.7 +/- 0.16 to -8.0 +/- 0.96 mV (lumen with
respect to bath) by the addition of glucose, and the change in PD was
inhibited by 10(-4) M phlorizin. The PD response to glucose was lost at day
2 of life, but the villus epithelium persisted. Amiloride, 10(-4) M, did
not alter PD or Na transport at either age. We conclude that the fetal rat
colon exhibits glucose-dependent Na flux at birth but that this property is
lost by 6-8 days.(ABSTRACT TRUNCATED AT 250 WORDS)
