Correlations between the amino acid pools of Hymenolepis diminuta and the rat intestine

Abstract

The composition of the free and protein amino acid pools of the rat intestine and of 16-day-old Hymenolepis diminuta have been determined at 1000 and 1600 h under ad libitum feeding conditions. The molar concentration (μmol/g dry-wt.) of the total intestinal and worm amino acid pools remained constant through time, although quantitatively individual amino acids differed significantly. All of 16 amino acids determined differed significantly in the comparisons between the intestinal and worm amino acid pools and between the time intervals. There was a high degree of correlation between the time intervals. There was also a high degree of correlation between the intestinal and worm pools based on their quantitative ranking, supporting the conclusion that there is little selective capacity involved in amino acid uptake by H. diminuta.Between 1000 and 1600 h the total worm amino acid pool increased by 73 μmol, mainly as a result of an increase in protein amino acids, indicating that worm protein biosynthesis was not inhibited by the changes in the intestinal pools. As the luminal free amino acid pool averaged only 20 μmol over this period, uptake by the worms would be equivalent to 60% of the luminal pool per hour.This high level of nutritional predation by the worms may be tolerated by the host because of extensive mucosal peptide absorption. A similar ability by the worms may explain why they can also tolerate the extensive amino acid fluctuations and fluxes that have been demonstrated between helminth and lumen.