Degradation of substance P by the neuroblastoma cells and their membrane.

Cells of the N-18 line of mouse neuroblastoma and their membrane degrade substance P added exogenously. The degradation by the cells and their membrane, examined by high-performance liquid chromatography, is strongly inhibited by EDTA but scarcely inhibited by captopril and phosphoramidon. Gly-Leu-Met-NH2 is the major cleavage product among C-terminal fragments of substance P in both cases. Thus, the degradation of substance P by the neuroblastoma cells and their membrane seems to take place mainly through the hydrolysis between Phe8-Gly9 by EDTA-sensitive protease(s).