GALACTOSE TRANSPORT ACROSS RAT SMALL INTESTINE IN VIVO FOLLOWING DISTAL RESECTIONS OF VARYING EXTENTS

¹ Departamento de Fisiologia Animal, Facultad de Farmacia, c/ Tramontana s/n, 41012 - Sevilla, Spain

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’ K_D's of the experimental groups increased, whereas ‘real’ K_m's did not significantly change. There were no significant differences in duodenal galactose absorption between 50 and 80% resected rats.