THE EFFECT OF JUGLONE ON THE MEMBRANE-POTENTIAL AND WHOLE-CELL K-LYMPHOCYTES( CURRENTS OF HUMAN)

Using flow cytometric membrane potential measurements with the oxonol dye, we determined that 5.7-57 mu M juglone depolarizes human lymphocy tes in a dose dependent manner. The depolarizing effect of juglone was verified by patch-clamp. Juglone decreased whole-cell n-type K+ curre nts in human peripheral blood lymphocytes and accelerated inactivation ; however, it did not influence the kinetics of activation of the K+ c onductance. The percentage increase in K+ channel inactivation rate an d the degree of drug induced block was independent of membrane potenti al. K+ channel block by juglone fully developed within 4 minutes and w as not removable by washing with drug Free extracellular solution. Blo cking of n-type K+ channels by juglone is in concert with its depolari zing effect on human lymphocytes. (C) 1996 Academic Press, Inc.