Ion channels ofFasciola hepaticaincorporated into planar lipid bilayers

Abstract

Ion channels are important target sites of anthelmintics, but little is known about those inFasciola hepatica. In this work, we applied a planar lipid bilayer technique to characterize the properties of single ion channels inF. hepatica. Under a 200/40 mMKCl gradient, a large conductance channel of 251 pS was observed in 18% of the membranes studied. The channel was selective to K+over Cl−with a permeability ratio of K+to Cl−(PK/PCl) of 4·9. Open state probability (Po) of the channel was less than 0·5 and dependent on voltage (−60~+40 mV) and Ca2+(~100 μM). The other two types of single channels observed in 11 and 5% of membranes, respectively, were a K+-permeable channel of 80 pS (PK/PCl=4·6) and a Cl−-permeable channel of 64 pS (PK/PCl=0·058). Open state probability of both channels showed little voltage dependence. The results indicate that distinct single channels of 60~251 pS are present in relative abundance and, in addition, that the planar lipid bilayer technique can be a useful tool for the study of single ion channels inF. hepatica.