SCHISTOSOMA - RATE OF GLUCOSE IMPORT IS ALTERED BY ACETYLCHOLINE INTERACTION WITH TEGUMENTAL ACETYLCHOLINE-RECEPTORS AND ACETYLCHOLINESTERASE

The blood dwelling stages of schistosomes have acetylcholinesterase (A ChE) and nicotinic-like acetylcholine receptors (nAChR) on their tegum ents. Both AChE and nAChR are concentrated on the dorsal surface of th e adult male, a major surface for nutrient uptake for the worm pair. E xposure of tegumental AChE and nAChR to acetylcholine (ACh), the natur al ligand of these molecules, has a consequence for the transporting f unction of this membrane in some schistosome species. The rate of gluc ose uptake in vitro by Schistosoma haematobium and Schistosoma bovis a dult worm pairs was enhanced by approximately 60% at blood concentrati ons of ACh. Schistosoma mansoni did not show a similar response. The s pecificity of the ACh interaction with nAChR and AChE was shown by abl ation of the effect with specific antagonists of nAChR (d-tubocurarine and alpha-bungarotoxin) and an inhibitor of AChE (BW284C51). The prim ary effect occurs on the tegument since alpha-bungarotoxin and BW284C5 1 do not penetrate the schistosome tegument. The species differences i n reliance on this mechanism are consistent with their relative sensit ivities to the AChE inhibitory drug, metrifonate. (C) 1995 Academic Pr ess, Inc.