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Research Article

K_bg and Kv1.3 channels mediate potassium efflux in the early phase of apoptosis in Jurkat T lymphocytes

¹University of Colima ²University of Tasmania

Submitted 6 February 2009 ; revised 14 September 2009 ; accepted in final form 24 September 2009

Microelectrode Ion Flux Estimation (the MIFE) and patch-clamp techniques were combined for non-invasive K⁺ flux measurements and recording of activities of the dominant K⁺ channels in the early phases of apoptosis in Jurkat cells. Staurosporine (STS, 1 µM) evoked rapid (peaking around 15 min) transient K⁺ efflux, which then gradually decreased. This transient K⁺ efflux occurred concurrently with the transient increase of the K⁺ background (K_bg)TRESK-like current density, followed by a drastic decrease and concomitant membrane depolarization. The Kv1.3 current density remained almost constant. Kv1.3 activation was not altered by STS, whereas the inactivation was shifted to more positive potentials. Contribution of K_bg and Kv1.3 channels to the transient and post-transient STS-induced K⁺ efflux components, respectively, was confirmed by the effects of bupivacaine, predominantly blocking K_bg current, and Kv1.3 specific blocker margatoxin. Channel-mediated K⁺ efflux provoked a substantial cellular shrinkage and affected the caspases activation.

apoptosis; Jurkat cells; Kv1.3; staurosporine; Kbg