title: Cytokine-induced nitric oxide production inhibits mitochondrial energy production and impairs contractile function in rat cardiac myocytes.
abstract: OBJECTIVE
  The present study examined whether nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) can directly inhibit aerobic energy metabolism and impair cell function in interleukin (IL)-1beta,-stimulated cardiac myocytes.
  
  
  BACKGROUND
  Recent reports have indicated that excessive production of NO induced by cytokines can disrupt cellular energy balance through the inhibition of mitochondrial respiration in a variety of cells. However, it is still largely uncertain whether the NO-induced energy depletion affects myocardial contractility.
  
  
  METHODS
  Primary cultures of rat neonatal cardiac myocytes were prepared, and NO2-/NO3- (NOx) in the culture media was measured using Griess reagent.
  
  
  RESULTS
  Treatment with IL-1beta (10 ng/ml) increased myocyte production of NOx in a time-dependent manner. The myocytes showed a concomitant significant increase in glucose consumption, a marked increase in lactate production, and a significant decrease in cellular ATP (adenosine 5'-triphosphate). These metabolic changes were blocked by co-incubation with N(G)-monomethyl-L-arginine (L-NMMA), an inhibitor of NO synthesis. Sodium nitroprusside (SNP), a NO donor, induced similar metabolic changes in a dose-dependent manner, but 8-bromo-cyclic guanosine 3',5'-monophosphate (8-bromo-cGMP), a cGMP donor, had no effect on these parameters. The activities of the mitochondrial iron-sulfur enzymes, NADH-CoQreductase and succinate-CoQreductase, but not oligomycin-sensitive ATPase, were significantly inhibited in the IL-1beta, or SNP-treated myocytes. Both IL-1beta and SNP significantly elevated maximum diastolic potential, reduced peak calcium current (I(Ca)), and lowered contractility in the myocytes. KT5823, an inhibitor of cGMP-dependent protein kinase, did not block the electrophysiological and contractility effects.
  
  
  CONCLUSIONS
  These data suggest that IL-1beta-induced NO production in cardiac myocytes lowers energy production and myocardial contractility through a direct attack on the mitochondria, rather than through cGMP-mediated pathways.
authors.affiliation: Second Department of Medicine, Kyoto Prefectural University of Medicine, Japan. tatsumi@koto.kpu-m.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Tatsumi
authors.forename: S
authors.initials: S
authors.lastname: Matoba
authors.forename: A
authors.initials: A
authors.lastname: Kawahara
authors.forename: N
authors.initials: N
authors.lastname: Keira
authors.forename: J
authors.initials: J
authors.lastname: Shiraishi
authors.forename: K
authors.initials: K
authors.lastname: Akashi
authors.forename: M
authors.initials: M
authors.lastname: Kobara
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
authors.forename: M
authors.initials: M
authors.lastname: Katamura
authors.forename: C
authors.initials: C
authors.lastname: Nakagawa
authors.forename: B
authors.initials: B
authors.lastname: Ohta
authors.forename: T
authors.initials: T
authors.lastname: Shirayama
authors.forename: K
authors.initials: K
authors.lastname: Takeda
authors.forename: J
authors.initials: J
authors.lastname: Asayama
authors.forename: H
authors.initials: H
authors.lastname: Fliss
authors.forename: M
authors.initials: M
authors.lastname: Nakagawa
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured / Q000502:physiology; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000502:physiology*; D005947:Glucose / Q000032:analysis / Q000378:metabolism; D006019:Glycolysis; D007249:Inflammation; D007375:Interleukin-1 / Q000502:physiology*; D019344:Lactic Acid / Q000032:analysis / Q000378:metabolism; D008929:Mitochondria, Heart / Q000378:metabolism*; D009200:Myocardial Contraction / Q000502:physiology*; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D007375:Interleukin-1; D009599:Nitroprusside; D019323:omega-N-Methylarginine; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; D019344:Lactic Acid; D000255:Adenosine Triphosphate; D019001:Nitric Oxide Synthase; D006152:Cyclic GMP; D005947:Glucose