Intracellular K+ concentration decrease is not obligatory for apoptosis |
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Authors: | Börjesson Sara I Englund Ulrika H Asif Muhammad H Willander Magnus Elinder Fredrik |
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Institution: | From the ?Department of Clinical and Experimental Medicine, Division of Cell Biology, and ;§Department of Science and Technology, Campus Norrköping, Linköping University, SE-581 85 Linköping, Sweden |
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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(+). |
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Keywords: | Apoptosis Caspase Oocyte Potassium Channels Xenopus Caspase-3 Electrophysiology Intracellular K+ Concentration K+-selective Microelectrode Xenopus laevis Oocyte |
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