title: Role of endogenous nitric oxide in classic preconditioning in rat hearts.
abstract: Ischemic preconditioning (IPC) protects the heart against subsequent sustained ischemia reperfusion (RP). Despite many triggers and signaling pathways, which seem to be involved in IPC, the IPC-mechanisms remain a controversial issue. One of them is endogenous production of nitric oxide (NO). To assess the role of NO in IPC and its relation with glycogen and glycolysis, the effects of inhibiting NO synthase with L-NAME (50 microM) were examined in IPC rat hearts perfused with medium containing 10 mM glucose. Left ventricular developed pressure-rate product (RPP) and end diastolic pressure (EDP), lactate and glycogen contents, and cell viability were measured. Global ischemia (25 min) was followed by 30 min RP. IPC consisted in one cycle of 3 min ischemia-5 min RP. IPC reduced EDP and improved RP recovery of RPP. L-NAME had no effects on the non-IPC group but abolished these effects of IPC. IPC reduced ischemic decrease of glycogen and the acceleration of glycolysis, and improved cell viability. L-NAME did not affect these effects of IPC. The results suggest that NO is ineffective on the noxious effects of ischemia-RP in non-IPC hearts and on the effects of IPC on cell viability, glycogenolysis and glycolysis whereas it is only involved in functional protection.
authors.affiliation: Cátedra de Fisiología, Facultad de Farmacia y Bioquímica, UBA and IQUIMEFA-CONICET, Junín 956, 1113 Buenos Aires, Argentina. gmarina@ffyb.uba.ar <gmarina@ffyb.uba.ar>
authors.forename: María G
authors.initials: MG
authors.lastname: Marina Prendes
authors.forename: Marcela
authors.initials: M
authors.lastname: González
authors.forename: Enrique A
authors.initials: EA
authors.lastname: Savino
authors.forename: Alicia
authors.initials: A
authors.lastname: Varela
mesh_terms: D000818:Animals; D002470:Cell Survival; D005260:Female; D006003:Glycogen / Q000378:metabolism; D006019:Glycolysis / Q000187:drug effects; D006321:Heart / Q000187:drug effects / Q000503:physiopathology*; D066298:In Vitro Techniques; D019194:Ischemic Preconditioning; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D009569:Nitric Oxide; D006003:Glycogen; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester