Structural and functional changes in mouse fibroblast cells treated with 2,3-dichloro-1,4-naphthoquinone (dichlone)

When strain L mouse fibroblasts were treated with the substituted quinone pesticide dichlone (2,3-dichloro-1,4-naphthoquinone), a rapid loss of intracellular potassium, ATP, and protein with a concomitant increase in intracellular water and volume occurred. Electron microscopic examination showed a nonreversible swelling of the cells associated with the formation of large protruding blebs. The findings indicate that dichlone can alter the permeability of the cell membrane which may be one of the sites of action of the pesticide in the fibroblast cells. Menadione (2-methyl-1,4-naphthoquinone), a synthetic vitamin K, also a substituted quinone, was found to be less effective in short-term incubation at corresponding concentrations, althought it did produce loss of K⁺ ions and protein from the cell. The action of dichlone was compared with that of model compounds which are known to act on plasma membranes (p-chloromercuribenzene sulfonate-PCMBS) and those which interfere with intracellular energy metabolism (combination of antimycin A plus iodoacetate). From the results reported in this paper it appears that dichlone acts in most respects, like PCMBS, by a direct interaction with membrane components, but unlike PCMBS, dichlone enters the cell rapidly and stimulates oxygen uptake probably by constituting a bypass of electron transfer.