Effect of thiabendazole and fenbendazole on glucose uptake and carbohydrate metabolism in Trichuris globulosa

14C-glucose uptake by adult Trichuris globulosa was found to be a non-linear function of time and limiting substrate concentration. The uptake was a two component process, an initial rapid burst, followed by a lower steady state. Linear transformation of the substrate saturation kinetics by Eadie plot gave a Kt value of 5 X 10(3) microM and Jmax of 5 mumol mg-1 dry weight min-1. Presence of the benzimidazole drugs, thiabendazole and fenbendazole, markedly inhibited the uptake process at concentrations in which the motility of the parasites was not affected. T. globulosa was found to possess the full complement of enzyme systems of glycolysis, Krebs cycle, phosphatases, transaminases and other NAD- and NADP-dependent enzymes. Thiabendazole and fenbendazole lowered the Vmax of most of these enzymes and affected the substrate-affinity constant (Km) in some of them. The mode of action of these drugs was discussed in the light of the data obtained.