title: Isoflurane favorably modulates guanosine triphosphate cyclohydrolase-1 and endothelial nitric oxide synthase during myocardial ischemia and reperfusion injury in rats.
abstract: BACKGROUND
  The authors investigated the hypothesis that isoflurane modulates nitric oxide (NO) synthesis and protection against myocardial infarction through time-dependent changes in expression of key NO regulatory proteins, guanosine triphosphate cyclohydrolase (GTPCH)-1, the rate-limiting enzyme involved in the biosynthesis of tetrahydrobiopterin and endothelial nitric oxide synthase (eNOS).
  
  
  METHODS
  Myocardial infarct size, NO production (ozone-mediated chemiluminescence), GTPCH-1, and eNOS expression (real-time reverse transcriptase polymerase chain reaction and western blotting) were measured in male Wistar rats with or without anesthetic preconditioning (APC; 1.0 minimum alveolar concentration isoflurane for 30 min) and in the presence or absence of an inhibitor of GTPCH-1, 2,4-diamino-6-hydroxypyrimidine.
  
  
  RESULTS
  NO2 production (158 ± 16 and 150 ± 13 pmol/mg protein at baseline in control and APC groups, respectively) was significantly (P < 0.05) increased 1.5 ± 0.1 and 1.4 ± 0.1 fold by APC (n = 4) at 60 and 90 min of reperfusion, respectively, concomitantly, with increased expression of GTPCH-1 (1.3 ± 0.3 fold; n = 5) and eNOS (1.3 ± 0.2 fold; n = 5). In contrast, total NO (NO2 and NO3) was decreased after reperfusion in control experiments. Myocardial infarct size was decreased (43 ± 2% of the area at risk for infarction; n = 6) by APC compared with control experiments (57 ± 1%; n = 6). 2, 4-Diamino-6-hydroxypyrimidine decreased total NO production at baseline (221 ± 25 and 175 ± 31 pmol/mg protein at baseline in control and APC groups, respectively), abolished isoflurane-induced increases in NO at reperfusion, and prevented reductions of myocardial infarct size by APC (60 ± 2%; n = 6).
  
  
  CONCLUSIONS
  APC favorably modulated a NO biosynthetic pathway by up-regulating GTPCH-1 and eNOS, and this action contributed to protection of myocardium against ischemia and reperfusion injury.
authors.affiliation: From the Department of Anesthesiology (I.B., D.W., J.P., Z.-D.G., S.S., D.C.W., J.R.K.), Department of Biophysics, Redox Biology Program (J.V.-V.), and Department of Pharmacology and Toxicology (D.C.W., J.R.K.), Medical College of Wisconsin, Milwaukee, Wisconsin.
authors.forename: Ines
authors.initials: I
authors.lastname: Baotic
authors.forename: Dorothee
authors.initials: D
authors.lastname: Weihrauch
authors.forename: Jesse
authors.initials: J
authors.lastname: Procknow
authors.forename: Jeanette
authors.initials: J
authors.lastname: Vasquez-Vivar
authors.forename: Zhi-Dong
authors.initials: ZD
authors.lastname: Ge
authors.forename: Shaan
authors.initials: S
authors.lastname: Sudhakaran
authors.forename: David C
authors.initials: DC
authors.lastname: Warltier
authors.forename: Judy R
authors.initials: JR
authors.lastname: Kersten
mesh_terms: D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D000818:Animals; D006136:GTP Cyclohydrolase / Q000096:biosynthesis*; D007530:Isoflurane / Q000008:administration & dosage*; D008297:Male; D017202:Myocardial Ischemia / Q000188:drug therapy / Q000201:enzymology*; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy / Q000201:enzymology*; D052250:Nitric Oxide Synthase Type III / Q000096:biosynthesis*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar
chemical_list: D018685:Anesthetics, Inhalation; D007530:Isoflurane; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D006136:GTP Cyclohydrolase