Effect of host dietary constituents on intestinal pH and the migrational behavior of the rat tapeworm Hymenolepis diminuta

Abstract

Changes in intestinal pH and in the position of Hymenolepis diminuta within the rat small intestine, have been followed for up to 7 h after feeding a 2.5-ml meal containing either 1 g or 3 g glucose, 2 g dextrin, 2 g galactose, 2 ml olive oil or an amino acid mixture containing 2.5 μmoles of 18 different amino acids.Both the quantity and quality of the dietary constituents have statistically significant effects (P < 0.001) on the pH gradients in the small intestine at any time up to 7 h after feeding. This implies that the buffering system of the rat is unable to maintain a very efficient homeostatic control of the hydrogen ion concentration in the intestine. The changes in intestinal pH are neither the cause of, nor are directly caused by, the migrational movements of the worms.The migrational response of the worms, which involved both scolex attachment sites and worm biomass (dry weight), varied depending on the quantity and quality of the meal.While the pattern of the migrational response was very similar following the feeding of 1 g and 3 g glucose, there was a 3-h delay after feeding 3 g glucose before the worms attained the maximum anteriad migrational position. Although there was an anteriad migration of worm biomass following the feeding of all the carbohydrates tested, the most marked anteriad movement was in response to feeding olive oil. Glucose does not appear to be the direct stimulus controlling the migrational behavior of H. diminuta.