Identification of Large-Conductance Calcium-Regulated K Channel in Human Dermal Mitochndria

Abstract

Potassium channels have been found in the inner mitochondrial membrane of various cells. These channels regulate the mitochondrial membrane potential, respiration and the production of reactive oxygen species. In this study, we identified the activity of a large-conductance Ca2+-regulated potassium channel (mitoBKCa channel) in mitoplasts isolated from a primary human dermal fibroblast cell line. A potassium selective current was recorded with a mean conductance of 280 ± 2 pS in a symmetrical 150 mM KCl solution. The mitoBKCa channel was activated by the Ca2+ and by potassium channel opener NS1619. The channel activity was irreversibly inhibited by paxilline, a selective inhibitor of the BKCa channels. In isolated fibroblast mitochondria NS1619 depolarized the mitochondrial membrane potential, stimulated non-phosphorylating respiration and decreased superoxide formation. Additionally, the α and β subunits (predominantly in the β3 form) of the BKCa channels were identified in fibroblast mitochondria. Our findings indicate, for the first time, the presence of a large-conductance Ca2+-regulated potassium channel in the inner mitochondrial membrane of human dermal fibroblasts. We show that a large-conductance Ca2+-regulated potassium channel functions in the inner mitochondrial membrane of human dermal fibroblasts. The electrophysiological and biochemical properties of this channel is similar to previously described mitochondrial potassium channels from other cell types.This study was supported by a grant MERIS PBS1/B8/1/2012 from the National Centre of Research and Development, Poland and partially by grant 2015/17/B/NZ1/02496 from Polish National Science Center.