Effect of two defined formula diets on jejunal and colonic uptake of hexoses in control and ileal resected rabbits.

An in vitro technique was used to measure the jejunal and colonic uptake of glucose and galactose in sham-operated control (CONT) rabbits and in animals with a surgical resection of the distal half of the small intestine (RES) performed six weeks previously. CONT and RES were fed ad libitum or pair-fed amounts of standard Purina chow, or ad libitum amounts of Ensure or Flexical HN for two weeks. Flexical NH differs from Ensure in its higher content of carbohydrate, essential fatty acids and polyunsaturated fatty acids but lower total dietary content of fat. The ad libitum chow-fed animals gained weight whereas the animals fed the defined formula diets lost weight. Weight gain was greater in RES than CONT fed chow, and weight loss was greater in RES than CONT fed Ensure or Flexical HN. Despite these differences in body weight, the dry and wet weights of the jejunum, and the adherent mucosal fluid volumes remained unchanged in CONT and RES fed the different diets. The intestinal morphology was unaffected by feeding Ensure or Flexical HN to control animals, whereas the villus cell size, villus and mucosal surface areas were lower in resected rabbits fed these diets than in resected animals fed chow. Glucose uptake was greatest in CONT and RES fed Flexical HN. Glucose uptake was higher in RES than CONT fed chow or Ensure but was lower in RES than CONT fed Flexical HN. In CONT fed Flexical HN, there was a lower value of the apparent Michaelis constant, Km*, and a higher value of the apparent passive permeability coefficient (Pd*) than in animals fed chow or Ensure. In RES there was lower Pd* in Ensure and Flexical HN-fed rabbits than in those fed chow, but the Km* was lower and the maximal transport rate, Jdm, was higher in animals given Flexical HN. The colonic uptake of glucose and the jejunal uptake of galactose was also influenced by feeding Ensure and Flexical HN. These differences in uptake in animals fed Ensure or Flexical-HN could not be explained by differences in body weight gain, since a different pattern of changes in glucose and galactose uptake was observed in CONT or RES rabbits exposed to restricted chow intake.(ABSTRACT TRUNCATED AT 400 WORDS)