Beta-scorpion toxin 2 from Centruroides noxius blocks voltage-gated K+ channels in human lymphocytes.
Using the patch-clamp technique, we determined that beta-scorpion toxin 2 from Centruroides noxius Hoffmann decreased whole-cell n-type K+ currents in human peripheral blood lymphocytes, with a half blocking concentration of approx. 5 microM. Toxin-2-accelerated inactivation, however, 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 Toxin 2 was instantaneous, not removable by washing with drug free extracellular solution. However, 10 mg/ml BSA in the bath lifted the toxin-induced block almost instantaneously and completely. Flow cytometric membrane potential measurements with the oxonol dye showed that Toxin 2 depolarizes human lymphocytes in concert with its K+ channel blocking effect.
Gáspár
R
R
Department of Biophysics, University Medical School, Debrecen, Hungary.
Bene
L
L
Damjanovich
S
S
Muñoz-Garay
C
C
Calderon-Aranda
E S
ES
Possani
L D
LD
D001463:Barbiturates; D004553:Electric Conductivity; D005434:Flow Cytometry; D005456:Fluorescent Dyes; D006801:Humans; D007555:Isoxazoles; D007700:Kinetics; D008214:Lymphocytes / Q000502:physiology*; D008564:Membrane Potentials; D009498:Neurotoxins / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000502:physiology*; D012604:Scorpion Venoms / Q000494:pharmacology*
D001463:Barbiturates; D005456:Fluorescent Dyes; D007555:Isoxazoles; D009498:Neurotoxins; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D012604:Scorpion Venoms; C052795:bis(1,3-dibutylbarbiturate)trimethine oxonol; C072990:toxin 2, Centruroides noxius