Title: Selective blockers of voltage-gated K+ channels depolarize human T lymphocytes: mechanism of the antiproliferative effect of charybdotoxin.

Authors: R J Leonard, M L Garcia, R S Slaughter, J P Reuben

Journal, date & volume: Proc. Natl. Acad. Sci. U.S.A., 1992 Nov 1 , 89, 10094-8

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/1279670

Abstract
Charybdotoxin (ChTX), a K+ channel blocker, depolarizes human peripheral T lymphocytes and renders them insensitive to activation by mitogen. We observed four types of K+ channels in human T cells: one voltage-activated, and three Ca(2+)-activated. To discern the mechanism by which ChTX depolarizes T cells, we examined the sensitivity of both the voltage-activated and Ca(2+)-activated K+ channels to ChTX and other peptide channel blockers. All four types were blocked by ChTX, whereas noxiustoxin and margatoxin blocked only the voltage-activated channels. All three toxins, however, produced equivalent depolarization in human T cells. We conclude that the membrane potential of resting T cells is set by voltage-activated channels and that blockade of these channels is sufficient to depolarize resting human T cells and prevent activation.