The adult male Schistosoma mansoni appears to regulate its motor activity by some rather unique mechanisms. One is that it appears to be dependent on environmental Ca++ for normal functioning of its musculature. Another is that the tegument appears to have electrical properties which allow this non-nervous tissue to regulate muscle activity within the parasite. One objective of the proposed research os tp determide to what degree and how the tegument functions in regulating inorganic ion fluxes between the parasite and its environment. This will be accomplished through an analysis, by means of ion selective Ca++ and Na+ electrodes, of the ionic composition of the tegumental cytoplasm, the muscle cytoplasm and interstitial spaces in the animal under control and experimental conditions. These experiments will be complimented with a biochemical study of the parasite's Ca++ pump. A second objective is an examination and characterization of the electrical properties of the tegumental membranes, using electrophysiological techniques, to determine if they are electrically excitable and capable of carrying active propagated potential changes which function to modulate motor activity within the parasite. Results from these studies may point to possibilities for development of agents specifically able to disrupt ion transport or active membrane responses. Such agents may prove to be uniquely effective and specific therapeutic agents against schistosomes.