Cardiovascular Research Advance Access [Accepted Manuscript] published online on May 21, 2009
Cardiovascular Research, doi:10.1093/cvr/cvp157
CONNEXIN43 IN CARDIOMYOCYTE MITOCHONDRIA CONTRIBUTES TO MITOCHONDRIAL POTASSIUM UPTAKE
1 Hospital Universitari Vall d'Hebron, Barcelona, Spain
2 Institut für Pathophysiologie, Essen, Germany
3 Universidad Autónoma, Madrid, Spain
Corresponding autor: David Garcia-Dorado, Servicio de Cardiología, Hospital Universitari Vall d'Hebron, Pg. Vall d'Hebron 119, 08035 Barcelona, Spain. dgdorado{at}vhebron.net Phone: +34-93-489-4038. Fax: +34-93-489-4032
Aims: Connexin43 is present at the inner membrane of cardiomyocyte mitochondria (mCx43), but its function remains unknown.
Methods and Results: In this study we verified the presence of mCx43 by a mass-spectrometry-based proteomic approach in purified mitochondrial preparations from mouse myocardium and determined by Western blot analysis that the C-terminus of mCx43 is oriented towards the intermembrane space. Cross-linking studies with dimethylsuberimidate indicated the presence of Cx43 hexamers in mitochondrial membranes. The contribution of Cx43 to both mitochondrial dye uptake and K+ flux was assessed in Cx43KI32 mice in which Cx43 had been replaced by Cx32. Uptake of the Cx43 hemichannel-permeant dye Lucifer Yellow was reduced in mitochondria from Cx43KI32 compared to wild-type mice. Mitochondrial K+ influx (PBFI fluorescence) was decreased in digitonin-permeabilized cardiomyocytes from Cx32 mutants compared to wild-type mice, and addition of the Cx43 hemichannel blocker 18
-glycyrrhetinic acid had an inhibitory effect on mitochondrial K+ influx in wild-type cardiomyocytes, but not in cardiomyocytes from Cx32 mutants.
Conclusion: These results indicate that mCx43 contributes to mitochondrial K+ flux in cardiomyocytes, potentially by forming hemichannel-like structures.
KEYWORDS connexins; hemichannels; myocardial ischemia; preconditioning; reperfusion
Time for primary review: 27 Days
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