Premium
Pivotal role of NOX‐2‐containing NADPH oxidase in early ischemic preconditioning
Author(s) -
Bell Robert M.,
Cave Alison C.,
Johar Sofian,
Hearse David J.,
Shah Ajay M.,
Shattock Michael J.
Publication year - 2005
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/fj.04-2774fje
Subject(s) - nadph oxidase , chelerythrine , chemistry , reactive oxygen species , oxidase test , peroxynitrite , protein kinase c , pharmacology , ischemic preconditioning , ischemia , biochemistry , medicine , superoxide , kinase , enzyme
ABSTRACT Reactive oxygen species (ROS)‐mediated signaling is implicated in early ischemic preconditioning (PC). A NOX‐2‐containing NADPH oxidase is a recognized major source of ROS in cardiac myocytes, whose activity is augmented by preconditioning mimetics, such as angiotensin II. We hypothesized that this oxidase is an essential source of ROS in PC. Hearts from wild‐type (WT) and NOX‐2 knockout (KO) mice were Langendorff perfused and subjected to 35 min ischemia/reperfusion with or without preceding PC or drug treatment. Infarct size was measured by triphenyl tetrazolium chloride staining, and NADPH oxidase activity by lucigenin chemiluminescence. PC significantly attenuated infarct size in WT (26±2% vs. control, 38±2%, P <0.05) yet was ineffective in KO hearts (33±3% vs. control, 34±3%). Concomitantly, PC significantly increased NADPH oxidase activity in WT (+41±13%; P <0.05), but not in KO (−5±18%, P =NS). The ROS scavenger MPG (N‐2‐mercaptopropionyl glycine, 300 µmol/L) abrogated PC in WT (39±2% vs. control, 33±1%). CCPA (2‐chloro N6 cyclopentyl adenosine, 200 nmol/L), a putative ROS‐independent PC trigger, significantly attenuated infarct size in WT, MPG‐treated WT and KO hearts (24±2, 23±1, and 20±3%, respectively, P <0.05). Furthermore, CCPA did not augment NADPH oxidase activity over control (+22±11%, P =NS). Inhibition of protein kinase C (PKC) with chelerythrine (CHE, 2 µmol/L) completely abrogated both PC (38±2% vs. CHE alone, 35±2%) and associated increases in oxidase activity (+3±10%, P =NS). PKC‐dependent activation of a NOX‐2‐containing NADPH oxidase is pivotally involved in early ischemic PC. However, adenosine receptor activation can trigger a ROS and NOX‐2 independent PC pathway.