THE EFFECT OF HIGH-MOLECULAR-WEIGHT GUAR GUM ON NET APPARENT GLUCOSE-ABSORPTION AND NET APPARENT INSULIN AND GASTRIC-INHIBITORY POLYPEPTIDEPRODUCTION IN THE GROWING PIG - RELATIONSHIP TO RHEOLOGICAL CHANGES IN JEJUNAL DIGESTA

The present study was designed to determine the quantitative effects o f starchy meals containing guar gum on rates of net apparent glucose a bsorption and net apparent insulin and gastric inhibitory polypeptide (GIP) production in growing pigs, The effects of these meals on the vi scosity of jejunal digesta were also examined and correlated to change s in glucose absorption, Four growing pigs were each given either a lo w-fat semi-purified diet (control) or the same diet supplemented with a high-molecular-weight guar gum at concentrations in the diet of 20 o r 40 g/kg, Blood samples were removed simultaneously via indwelling ca theters from the mesenteric artery and the hepatic portal vein, Sample s of jejunal digesta were removed via a T-piece cannula and used immed iately for viscosity measurements at 39 degrees, The 'zero-shear' visc osity of each sample was then calculated, Blood-flow measurements were made using an ultrasonic flow probe fitted to the hepatic portal vein , All measurements were made at intervals of 10 or 30 min during a 4 h postprandial period, Meals containing guar gum significantly increase d (P < 0.05) the viscosity of jejunal digesta, an effect that was stro ngly dependent on the concentration of guar gum in the original diet, No significant differences in blood-flow rates were found between the control and guar-containing diets, Both concentrations of guar gum sig nificantly reduced (P < 0.05) glucose absorption and insulin and GIP s ecretion rates over the 4 h postprandial period, An inverse relationsh ip between the rate of glucose absorption and the 'zero-shear' viscosi ty of jejunal digesta was found, This study also provides direct evide nce for the important role played by the enteroinsular axis in modifyi ng the glycaemic response to a meal containing guar gum.