Continuous synthesis of glycogen by individual worm pairs of Schistosoma mansoni inside the veins of the final host

Hamsters infected with Schistosoma mansoni were operated upon to install a permanent canula into their blood stream. After recovery of the hamster, this canula was used for the injection of radioactively labelled glucose. In this way the glycogen metabolism of S. mansoni could be studied while the parasites remained undisturbed in their natural habitat. The consecutive injection of [U-14C]glucose and [1-3H]glucose permitted an analysis of possible changes in the glycogen synthesis of individual worm pairs with time. The results showed that the synthesis of glycogen by each worm pair was fairly constant with time. Furthermore, all individual worm pairs synthesised glycogen continuously; not even 2 min passed without its formation. Only small differences in glycogen synthesis were observed between parasites isolated from different locations in the veins of the hamster. These results exclude the possibility that the worm pairs had alternating periods of glycogen synthesis and degradation, and they also disprove the idea that synthesis and degradation occur at two different sites in the bloodstream of the hamster. The experiments further showed that glycogen synthesis was proportional to the amount of glycogen already present, which in turn was shown to be proportional to the size of the parasite. From this study it can be concluded that the replenishment of the endogenous glycogen reserves of S. mansoni is not induced by a marked decrease in the glycogen levels, but occurs slowly and continuously.