EPR evidence for nitric oxide production from guanidino nitrogens of L-arginine in animal tissues in vivo.
Administration of Fe(2+)-citrate complex (50 mg/kg of FeSO4 or FeCl2 plus 250 mg/kg of sodium citrate) subcutaneously in the thigh or Escherichia coli lipopolysaccharide (LPS, 1 mg/kg) intraperitoneally, (i.p.) to mice induced NO formation in the livers in vivo at the rate of 0.2-0.3 micrograms/g wet tissue per 0.5 h. The NO synthesized was specifically trapped with Fe(2+)-diethyldithiocarbamate complex (FeDETC2), formed from endogenous iron and diethyldithiocarbamate (DETC) administered i.p. 0.5 h before decapitation of the animals. NO bound with this trap resulted in the formation of a paramagnetic mononitrosyl iron complex with DETC (NO-FeDETC2), characterized by an EPR signal at g perpendicular = 2.035, g parallel = 2.02 with triplet hyperfine structure (HFS) at g perpendicular. This allowed quantification of the amount of NO formed in the livers. An inhibitor of enzymatic NO synthesis from L-arginine, NG-nitro-L-arginine (NNLA, 50 mg/kg) attenuated the NO synthesis in vivo. L-Arginine (500 mg/kg) reversed this effect. Injection of L-[guanidineimino-15N2]arginine combined with Fe(2+)-citrate or LPS led to the formation of the EPR signal of NO-FeDETC2 characterized by a doublet HFS at g perpendicular, demonstrating that the NO originates from the guanidino nitrogens of L-arginine in vivo.
Kubrina
L N
LN
Institute of Chemical Physics, USSR Academy of Sciences, Moscow, Russia.
Caldwell
W S
WS
Mordvintcev
P I
PI
Malenkova
I V
IV
Vanin
A F
AF
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D004050:Ditiocarb / Q000378:metabolism / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D007501:Iron / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism*; D019335:Nitroarginine; D009590:Nitrogen Radioisotopes
D009590:Nitrogen Radioisotopes; D019335:Nitroarginine; D009569:Nitric Oxide; D001120:Arginine; D004050:Ditiocarb; D007501:Iron