Localization of Sulfonylurea Receptor Subunits, SUR2A and SUR2B, in Rat Heart

• DOI: 10.1369/jhc.6a7104.2007
• Publication Date: 2007-04-18T01:58:16Z
• Authors: Ming Zhou; Hui-Jing He; Ryoji Suzuki; Ke-Xiang Liu; Osamu Tanaka; Masaki Sekiguchi; Hideaki Itoh; Katsumasa Kawahara; Hiroshi Abe
• Keywords: Male; 0301 basic medicine; Potassium Channels; Immune Sera; Myocardium; Receptors, Drug; Immunoblotting; Sulfonylurea Receptors; Coronary Vessels; Immunohistochemistry; Rats; 3. Good health; Protein Subunits; 03 medical and health sciences; Organ Specificity; Animals; ATP-Binding Cassette Transporters; Myocytes, Cardiac; Potassium Channels, Inwardly Rectifying; Rats, Wistar

To understand the possible functions and subcellular localizations of sulfonylurea receptors (SURs) in cardiac muscle, polyclonal anti-SUR2A and anti-SUR2B antisera were raised. Immunoblots revealed both SUR2A and SUR2B expression in mitochondrial fractions of rat heart and other cellular fractions such as microsomes and cell membranes. Immunostaining detected ubiquitous expression of both SUR2A and SUR2B in rat heart in the atria, ventricles, interatrial and interventricular septa, and smooth muscles and endothelia of the coronary arteries. Electron microscopy revealed SUR2A immunoreactivity in the cell membrane, endoplasmic reticulum (ER), and mitochondria. SUR2B immunoreactivity was mainly localized in the mitochondria as well as in the ER and cell membrane. Thus, SUR2A and SUR2B are not only the regulatory subunits of sarcolemmal KATPchannels but may also function as regulatory subunits in mitochondrial KATPchannels and play important roles in cardioprotection. (J Histochem Cytochem 55: 795–804, 2007)