Effect of Inhibitors on Phosphate Uptake in Excised Gills of the Mussel ( Mytilus edulis )

Summary

Excised fragments of gills of Mytilus edulis L., a pelecypod mollusk, were irrigated with artificial sea water containing P³². The rate of uptake of phosphate in the presence of 0.001 M inhibitors was compared with the control rate. Inhibition of phosphate uptake in the presence of cyanide, sulfide, and iodoacetate, and the lack of inhibition by azide and fluoride, are considered from the point of view of available knowledge of the penetration of such substances into cells. Cyanide and sulfide, being salts of weak acids, penetrate the cells and probably affect the turnover rate of intracellular phosphate. The lack of effect with fluoride is consistent with its existence in the completely dissociated state. Iodoacetate, also completely ionized, may be effective at the cell surface, affecting the permeability of the cell to phosphate. The apparent rise in the rate of phosphate uptake in the presence of cysteine remains unexplained.