Spin trapping of nitric oxide produced in vivo in septic-shock mice.
A nitric oxide (.NO) spin-trapping technique combined with electron paramagnetic resonance (EPR) spectroscopy has been employed to measure the in vivo production of .NO in lipopolysaccharide (LPS)-treated mice. The in vivo spin-trapping of .NO was performed by injecting into mice a metal-chelator complex, consisting of N-methyl-D-glucamine dithiocarbamate (MGD) and reduced iron (Fe2+), that binds to .NO and forms a stable, water-soluble [(MGD)2-Fe(2+)-NO] complex, and by monitoring continuously the in vivo formation of the latter complex using an S-band EPR spectrometer. At 6 h after intravenous injection of LPS, a three-line EPR spectrum of the [(MGD)2-Fe(2+)-NO] complex, was observed in the blood circulation of the mouse tail; the [(MGD)2-Fe2+] complex was injected subcutaneously 2 h before EPR measurement. No signal was detected in control groups. Administration of NG-monomethyl-L-arginine, an .NO synthase inhibitor, caused a marked reduction in the in vivo EPR signal of the [(MGD)2-Fe(2+)-NO] complex, suggesting that the .NO detected is synthesized via the arginine-nitric oxide synthase pathway. The results presented here demonstrated, for the first time, the in vivo real time measurement of .NO in the blood circulation of conscious, LPS-treated animals.
Lai
C S
CS
Biophysics Research Institute, Medical College of Wisconsin, Milwaukee 53226.
Komarov
A M
AM
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002614:Chelating Agents; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005260:Female; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000633:toxicity*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism*; D009928:Organ Specificity; D012772:Shock, Septic / Q000378:metabolism*; D013012:Sorbitol / Q000031:analogs & derivatives; D013113:Spin Labels; D013859:Thiocarbamates; D013997:Time Factors; D019323:omega-N-Methylarginine
D002614:Chelating Agents; D008070:Lipopolysaccharides; D013113:Spin Labels; D013859:Thiocarbamates; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D013012:Sorbitol; C041262:N-methyl-D-glucamine dithiocarbamate; D001120:Arginine