title: Intracellular K+ concentration decrease is not obligatory for apoptosis.
abstract: K(+) efflux is observed as an early event in the apoptotic process in various cell types. Loss of intracellular K(+) and subsequent reduction in ionic strength are suggested to release the inhibition of proapoptotic caspases. In this work, a new K(+)-specific microelectrode was used to study possible alterations in intracellular K(+) in Xenopus laevis oocytes during chemically induced apoptosis. The accuracy of the microelectrode to detect changes in intracellular K(+) was verified with parallel electrophysiological measurements. In concordance with previous studies on other cell types, apoptotic stimuli reduced the intracellular K(+) concentration in Xenopus oocytes and increased caspase-3 activity. The reduction in intracellular K(+) was prevented by dense expression of voltage-gated K (Kv) channels. Despite this, the caspase-3 activity was increased similarly in Kv channel-expressing oocytes as in oocytes not expressing Kv channels. Thus, in Xenopus oocytes caspase-3 activity is not dependent on the intracellular concentration of K(+).
authors.affiliation: Department of Clinical and Experimental Medicine, Division of Cell Biology, Campus Norrköping, Linköping University, SE-581 85 Linköping, Sweden.
authors.forename: Sara I
authors.initials: SI
authors.lastname: Börjesson
authors.forename: Ulrika H
authors.initials: UH
authors.lastname: Englund
authors.forename: Muhammad H
authors.initials: MH
authors.lastname: Asif
authors.forename: Magnus
authors.initials: M
authors.lastname: Willander
authors.forename: Fredrik
authors.initials: F
authors.lastname: Elinder
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism*; D002478:Cells, Cultured; D008839:Microelectrodes; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D053148:Caspase 3; D011188:Potassium