High-methoxyl pectin has greater enhancing effect on glucose uptake in intestinal perfused rats

Objective Pectins have been known to decrease blood glucose levels. However, the mechanism of this effect is unclear. The direct action of various pectins (high- or low-methoxyl pectins) on the intestinal absorption of glucose was investigated in gut-perfused rats. Methods After equilibrium, jejunal and ileal segments were simultaneously perfused with an isotonic electrolyte solution (pH 7.4) containing glucose (10 mM/L) and high- or low-methoxyl pectins (10 g/L). Each test or control solution was perfused in a random sequence, with perfusion times of 30 min. Changes in glucose concentration of perfusate solution reservoir were determined over the experimental period. Results High- and low-methoxyl pectins in the perfusate significantly inhibited jejunal uptake of glucose compared with the control (P < 0.05). High-methoxyl pectins had greater inhibitive effect on intestinal absorption of glucose than low-methoxyl pectins. The observed changes in glucose and water absorptions caused by high- or low-methoxyl pectins were reversible by switching to a pectin-free perfusate. In addition, net water absorption changed to secretion after addition of high- or low-methoxyl pectins. Conclusions These results suggest that the decrease in intestinal absorption of glucose observed after perfusion of high- or low-methoxyl pectins may be caused by viscosity-related increases in mucosal unstirred layer thickness.