EPR spectroscopy studies on the structural transition of nitrosyl hemoglobin in the arterial-venous cycle of DEANO-treated rats as it relates to the proposed nitrosyl hemoglobin/nitrosothiol hemoglobin exchange.
In vivo studies show a dynamic cycle in which alpha-nitrosylated hemoglobin is mainly in the relaxed state in arterial blood of rats treated with 2-(N,N-diethylamino)-diazenolate-2-oxide, but converts mainly to the tense state during the arterial-venous transit. A detailed analysis shows that different electron paramagnetic resonance spectra recorded for alpha-nitrosyl hemoglobin in arterial and venous blood at 77 K originate only from a different ratio between 5- and 6-coordinate heme without any change in the concentration of nitrosyl hemoglobin. In venous blood, the five- and six-coordination equilibrium of the alpha-nitrosyl heme is shifted in favor of the 5-coordinate state (58% venous vs. 20% arterial). These results are not consistent with the recently proposed exchange of nitrosyl heme with the beta-93 nitrosothiol group of hemoglobin during the arterial-venous cycle.
Jaszewski
Adrian R
AR
Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA. jaszews1@niehs.nih.gov
Fann
Yang C
YC
Chen
Yeong Renn
YR
Sato
Keizo
K
Corbett
Jean
J
Mason
Ronald P
RP
D000818:Animals; D004048:Diethylamines / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D006418:Heme / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry*; D008280:Magnetics; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D009589:Nitrogen Oxides; D051381:Rats; D011916:Rats, Inbred F344; D013438:Sulfhydryl Compounds / Q000737:chemistry*
D004048:Diethylamines; D006454:Hemoglobins; D009589:Nitrogen Oxides; D013438:Sulfhydryl Compounds; C008657:nitrosyl hemoglobin; D009569:Nitric Oxide; D006418:Heme; C087229:diethylamine dinitric oxide adduct