title: Cardioprotective PKG-independent NO signaling at reperfusion.
abstract: Cell models of ischemic preconditioning (IPC) indicate nitric oxide (NO) is involved in protection accruing during reoxygenation but disagree whether it acts through PKG. Using a more relevant intact heart model, we studied isolated rabbit hearts subjected to 30-min coronary artery occlusion/120-min reperfusion. We previously found protection from PKG activator 8-(4-chlorophenylthio)-guanosine 3',5'-cyclic monophosphate (CPT-cGMP) at reperfusion was blocked by A(2b) adenosine receptor (A(2b)AR), ERK, or phosphatidylinositol 3-kinase (PI3-kinase) blockers. In this investigation A(2b)AR agonist BAY 60-6583 or CPT-cGMP at reperfusion reduced infarction comparably to IPC. Their protection was abrogated by N(ω)-nitro-l-arginine methyl ester (l-NAME), suggesting a PKG-independent NO synthase in IPC's mediator pathway downstream of PKG and A(2b)AR. NO donor S-nitroso-N-acetyl-d,l-penicillamine (SNAP) at reperfusion also protected. This protection was not blocked by PI3-kinase inhibitor wortmannin or ERK antagonist PD-98059, suggesting NO acted downstream of these kinases. Protection from SNAP was not affected by mitochondrial ATP-sensitive K(+) channel closer 5-hydroxydecanoate, PKC antagonist chelerythrine, reactive oxygen species scavenger N-2-mercaptopropionylglycine, or soluble guanylyl cyclase antagonist 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). Absence of ODQ effect indicated NO was acting independently of PKG. BAY 58-2667, a soluble guanylyl cyclase activator, was protective, and l-NAME blocked its infarct-sparing effect, indicating a second signaling event dependent on NO generation but independent of PKG. SB216763, a blocker of glycogen synthase kinase-3β (GSK-3β), decreased infarct size, and its infarct-sparing effect was not affected by l-NAME, suggesting GSK-3β acted downstream or independently of NO. Hence, NO signaling occurs in IPC's mediator pathway downstream of Akt and ERK, and its protection is independent of PKG.
authors.affiliation: Department of Physiology, University of South Alabama College of Medicine, Mobile, Alabama 36688, USA. mcohen@usouthal.edu
authors.forename: Michael V
authors.initials: MV
authors.lastname: Cohen
authors.forename: Xi-Ming
authors.initials: XM
authors.lastname: Yang
authors.forename: Yanping
authors.initials: Y
authors.lastname: Liu
authors.forename: Nataliya V
authors.initials: NV
authors.lastname: Solenkova
authors.forename: James M
authors.initials: JM
authors.lastname: Downey
mesh_terms: D058908:Adenosine A2 Receptor Agonists / Q000494:pharmacology; D000818:Animals; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism*; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005260:Female; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism; D006439:Hemodynamics; D066298:In Vitro Techniques; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D009203:Myocardial Infarction / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D015428:Myocardial Reperfusion Injury / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D011817:Rabbits; D043704:Receptor, Adenosine A2B / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D058908:Adenosine A2 Receptor Agonists; D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D043704:Receptor, Adenosine A2B; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D017869:Cyclic GMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D038362:Glycogen Synthase Kinase 3; D006162:Guanylate Cyclase