Absorption of glucose polymers from canine jejunum deprived of pancreatic amylase

We evaluated the absorption of glucose polymers in canine jejunal Thiry-Vella fistulas proven to be free of pancreatic amylase. Medium-length oligomers with degrees of polymerization of 6 through 10 glucose units (DP 6–10) and long-chain material (DPavg23) were isolated from a cornstarch hydrolysate. We perfused 90, 180, and 360 mg/dl solutions of glucose, DP 6–10, and DPavg23 at 0.4, 1.9, and 3.4 ml/min. At all perfusion rates carbohydrate absorption decreased as the chain length of the oligomers increased, and these differences persisted even at the slowest perfusion rate employed. In two additional animals the fistulas were perfused at 3.4 ml/min with the three test carbohydrates at concentrations of 90, 180, 225, 270, 315, 360, 405, and 450 mg/dl. At this flow rate, the assimilative process of DP 6–10 and the long-chain fraction appeared to be saturated at carbohydrate concentrations above 360 mg/dl, whereas the absorption of glucose was linearly related to concentration throughout the range studied. With both groups of polymers, the fluid emerging from the fistula was virtually free of glucose, a finding that suggests that polymer digestion, not glucose absorption, is the rate-limiting step for polymer assimilation.