Galactose transport across rat small intestine in vivo following distal resections of varying extents.

The kinetics of D-galactose absorption across rat small intestine in sham, 50 and 80% distal intestinal resected animals, have been studied under in vivo conditions. After 5 months post-resection the total galactose absorption was increased. The relationship between total absorption of substrate and its concentration in the perfusate showed a non-saturable component and a saturable one that can be inhibited by phloridzin, both in control and remnant intestine. The slope of the line that represents the non-saturable component is greater in remnant duodenum and jejunum, indicating that the apparent mass-transfer coefficient, K'D, was increased by distal resection. Non-linear fitting of the saturable component data gave an apparent maximal galactose transport rate (J'max, nmol/cm2 . min) of 134 +/- 13 (sham), 132 +/- 9 (50% resected), 139 +/- 9 (80% resected) in duodenum and of 103 +/- 11 (sham) and 106 +/- 12 in jejunum. Apparent Michaelis constants (K'm, mM) of 12.1 +/- 3.2 (sham), 12.3 +/- 2.2 (50% resected) and 13.3 +/- 2.2 (80% resected) in duodenum and of 11.6 +/- 3.7 (sham) and 12.8 +/- 3.7 (50% resected) in jejunum were found. Correction of the kinetic constants for the unstirred water layer (u.w.l.) effects showed that the differences between 'real' KD's of the experimental groups increased, whereas 'real' Km's did not significantly change. There were no significant differences in duodenal galactose absorption between 50 and 80% resected rats.