Inactivation of regulatory volume decrease in human peripheral blood lymphocytes by N-ethylmaleimide

The sulfhydryl group reagent N-ethylmaleimide was found to inhibit in a dose dependent manner regulatory volume decrease of human peripheral lymphocytes swollen in buffered hyposmotic NaCl media. In hyposmotic KCl media NEM treated lymphocytes prevented an additional secondary swelling seen in control lymphocytes. The data suggest that N-ethylmaleimide acts on ion transport mechanisms involved in volume regulatory changes. This effect contrasts with the stimulation by N-ethylmaleimide of apparently volume sensitive K/Cl fluxes in certain mammalian red cells.