Involvement of membrane sulfhydryl groups in apomorphine-induced inhibition of neutrophil migration.

Apomorphine inhibits fMet-Leu-Phe stimulated migration of rabbit neutrophils, in the absence of albumin, in the concentration range of 1-20 microM. In the presence of albumin inhibition by apomorphine occurs at higher concentrations. Casein-stimulated migration, and non-stimulated migration are equally inhibited by apomorphine. The presence or absence of extracellular Ca2+ has no effect on the degree of inhibition by apomorphine. The ability of albumin to interfere with apomorphine inhibition of migration is diminished after treatment of albumin with the sulfhydryl reagent N-ethylmaleimide. Sulfhydryl compounds, such as glutathione and dithiothreitol, strongly interfere with apomorphine inhibition. The results suggest that the inhibiting effect of apomorphine is due to a reaction with sulfhydryl groups, the intactness of which is required for neutrophil migration, and which are probably located on the plasma membrane.