Originally published as JHC exPRESS on June 27, 2005. doi:10.1369/jhc.5A6736.2005
Volume 53 (12): 1491-1500, 2005 Copyright ©The Histochemical Society, Inc. ATP-sensitive K+-channel Subunits on the Mitochondria and Endoplasmic Reticulum of Rat Cardiomyocytes
Department of Anatomy, Akita University School of Medicine, Akita, Japan (MZ,H-jH,HA); Department of Material-process Engineering and Applied Chemistry for Environment, Akita University Faculty of Engineering and Resource Science, Akita, Japan (HI); Department of Morphology, Tokai University School of Medicine, Bohseidai, Isehara, Kanagawa, Japan (OT,MS); and Department of Physiology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan (YY,KK) Correspondence to: Ming Zhou, MD, PhD, Department of Anatomy, Akita University School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan. E-mail: mzhou{at}med.akita-u.ac.jp ATP-sensitive K+ (KATP) channel subunits on the subcellular structures of rat cardiomyocytes were studied with antibodies against Kir6.1 and Kir6.2. According to the results of Western blot analysis, Kir6.1 was strongly expressed in mitochondrial and microsome fractions, and faintly expressed in cell membrane fraction, whereas Kir6.2 was mainly expressed in the microsome fraction and weakly in cell membrane and mitochondrial fractions. Immunohistochemistry showed that Kir6.1 and Kir6.2 were expressed in the endocardium, atrial and ventricular myocardium, and in vascular smooth muscles. Immunoelectron microscopy revealed that Kir6.1 immunoreactivity was mainly localized in the mitochondria, whereas Kir6.2 immunoreactivity was mainly localized in the endoplasmic reticulum and a few in the mitochondria. Both Kir6.1 and Kir6.2 are candidates of mitochondrial KATP channel subunits. The data obtained in this study will be useful for analyzing the composition of KATP channels of cardiomyocytes and help to understanding the cardioprotective role of KATP channels during heart ischemia. (J Histochem Cytochem 53:14911500, 2005)
Key Words: ATP-sensitive K+ channels mitochondria endoplasmic reticulum rat cardiomyocytes immunoelectron microscopy
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