KINETIC-ANALYSIS OF D-XYLOSE ABSORPTION AFTER ITS INTRAGASTRIC ADMINISTRATION TO MARES DEPRIVED OF FOOD

Multicompartmental analysis was applied to study the kinetics of D-xyl ose distribution after its intragastric administration to healthy mare s deprived of food for 12, 36, 72, and 96 hours. Disposition of D-xylo se was described by a 5-compartment model. Maximal plasma D-xylose con centration was similar for 12 and 36 hours of food deprivation and was greater (P = 0.0001) than the values for 72 and 36 hours. Peak concen tration of D-xylose appeared progressively later as food deprivation p roceeded (P 0.0001). Fractional rate of transfer (k(1,6)) was less aft er 36 hours of food deprivation, compared with 12 hours (P = 0.0001), and percentage of D-xylose absorbed was reduced (P = 0.0441) after foo d deprivation. Fractional rate of transfer (k(6,5)), representing gast ric emptying, tended to progressively decrease with food deprivation. Results indicated that formal kinetic analysis can be applied to D-xyl ose absorption kinetics in horses. Reduction in the extent of D-xylose absorption after food deprivation may be partly caused by decreased r ate of D-xylose absorption across the small intestinal mucosa, but oth er factors, such as gastric emptying and nonabsorptive losses, may als o be involved.