Studies on the effect of hexachlorophene on the cuticle and the intestine from liver flukes, Fasciola hepatica L., incubated in vitro
Acta Veterinaria Scandinavica 8: Suppl 20:9-28
Hexachlorophene [HCP] is lipophilic. Its distribution coefficient between hexane and phosphate buffer (0.1 _M; pH 8.5) was 4.4 + 0.4 at + 20[degree]C. Its dimethyl-ether without free phenolic groups is more lipophilic but devoid of fasciolicidal properties in vitro. The electron microscopic appearance of the cuticle and intestine of F. hepatica was investigated. C14-labelled HCP could be followed through the cuticle to adjacent tissues. The intestine did not show an observable uptake at the concentrations used. The HCP, which did not seem to be metabolized by the fluke, was bound in an easily reversible way to some components of the fluke. HCP gives rise to ultrastructural changes in the outer part of the cuticle i.e. a dilatation of the cisterns of the endoplasmic reticulum which are filled with a f locculent material. Occasionally bleb formation was observed at the surface of the cuticle, the plasma membrane of which appeared disrupted. The mitochondria were sometimes also increased in size. Three enzyme systems, supposedly located along the road of entrance of HCP, i.e. ATPase connected to membranes, succinate oxidase connected to mitochondria, and cholinesterase connected to cells adjacent to the cuticle, were chosen. All of them were sensitive to HCP when its effect was tested on fluke homogenates. However, only the succinate oxidase system from homogenates of flukes just killed in HCP showed reduced activity.