The effect of juglone on the membrane potential and whole-cell K+ currents of human lymphocytes.
Using flow cytometric membrane potential measurements with the oxonol dye, we determined that 5.7-57 microM juglone depolarizes human lymphocytes in a dose dependent manner. The depolarizing effect of juglone was verified by patch-clamp. Juglone decreased whole-cell n-type K+ currents in human peripheral blood lymphocytes and accelerated inactivation; however, it did not influence the kinetics of activation of the K+ conductance. The percentage increase in K+ channel inactivation rate and the degree of drug induced block was independent of membrane potential, K+ channel block by juglone fully developed within 4 minutes and was not removable by washing with drug free extracellular solution. Blocking of n-type K+ channels by juglone is in concert with its depolarizing effect on human lymphocytes.
Varga
Z
Z
Department of Biophysics, University Medical School, Debrecen, Hungary.
Bene
L
L
Pieri
C
C
Damjanovich
S
S
Gáspár
R
R
D003603:Cytotoxins / Q000494:pharmacology*; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D008214:Lymphocytes / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D009285:Naphthoquinones / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000502:physiology*; D026902:Potassium Channel Blockers
D003603:Cytotoxins; D009285:Naphthoquinones; D026902:Potassium Channel Blockers; D011188:Potassium; C005134:juglone