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Identification, localization, and electrophysiologic characterization of small Ca 2+ ‐sensitive K + channels in cardiac mitochondria
Author(s) -
Gadicherla Ashish Kumar,
Camara Amadou KS,
Kwok Wai-Meng,
Zhou Yifan,
Stowe David F
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.695.8
Subject(s) - mitochondrion , chemistry , cardioprotection , biophysics , mitochondrial apoptosis induced channel , apamin , biochemistry , inner mitochondrial membrane , ischemia , potassium channel , medicine , biology
It is now well recognized that protective strategies against cardiac ischemia reperfusion (IR) injury involve not only activating cytosolic and mitochondrial factors but also attenuating deleterious mitochondrial (m) factors like excess reactive O 2 species (ROS) and excess mCa 2+ loading. We showed previously that activation of the big Ca 2+ sensitive K + channel with NS1619 improved function and decreased levels of ROS and mCa + after IR injury; it was not known if cardiac myocyte mitochondria were targets of the drug. We also recently found that DCEBIO, a small Ca 2+ ‐sensitive K + channel (SK Ca ) agonist, exerts protective effects similar to NS1619. Here we used a multi‐modal approach to determine if the SK Ca is indeed present and functional in cardiac mitochondria. After percoll gradient purification of mitochondria we used immuno‐histochemical localization of SK Ca , western blot detection and isoelectric focusing (IEF) to seek to identify and localize the channel. Protein fractions from IEF identified as SK Ca were then incorporated into planar lipid bilayers to measure channel activity. We found that SK Ca was localized to mitochondria and exhibited functional channel activity (conductances of 230, 730 pS in 200 mM KCl) that were blocked by apamin, a blocker of SK Ca channels. These studies point towards the presence of SK Ca channels in mitochondria and their potential role in cardioprotection against IR injury.