A VESICLE PREPARATION FOR RESOLVING SINGLE-CHANNEL CURRENTS IN TEGUMENT OF MALE SCHISTOSOMA-MANSONI

A tegumental vesicle preparation from adult male Schistosoma mansoni w as developed that allows the resolution of single ion-channel currents . Adult male schistosomes were exposed to a low pH (3.75) medium for a period of approximately 30 min at 37 degrees C. During this period sm ooth vesicles formed from the tegument. Fluorescence microscopy follow ing staining of the tegument with the dye, 5-N-[octadecanoyl] aminoflu orescein (AF-18), transmission electron microscopy and scanning electr on microscopy revealed that the vesicles were produced from the outer tegumental membrane. The fluorescence studies showed the presence of t he double bilayer structure of the outer membrane in > 41 % of the ves icles. These studies suggested that the preparation is suitable for si ngle-channel recording with the patch-clamp technique. Cell-attached a nd isolated inside-out patch recordings of ion-channel activity were o btained with giga-ohm resistance seals. Different types of ion-channel were recorded from tegumental Vesicles from male schistosomes, illust rating the potential of the technique. The channels observed included: a non-selective cation channel (360 pS); a K+ channel (with a conduct ance of 115 pS in high bath-K conditions); and a Cl- selective channel (20 pS). The currents of these ion-channels may cross the double bila yer of the outer tegumental membrane.