M. Kohno et al., ESR DEMONSTRATION OF NITRIC-OXIDE PRODUCTION FROM NITROGLYCERIN AND SODIUM-NITRITE IN THE BLOOD OF RATS, Free radical biology & medicine, 18(3), 1995, pp. 451-457
Electron spin resonance (ESR) spectra of iron-metal complexes formed b
y the reaction between nitric oxide ((NO)-N-.) and hemoglobin (Hb), re
ferred to as nitrosylhemoglobin (HE-NO), were observed in rat blood tr
eated in vitro and in vivo with nitroglycerin (GTN) at 77K. The same t
ypes of spectra were also detected in rats treated with sodium nitrite
(NaNO2). Two types of Hb-NO, which were identified by ESR parameters
of g values and superhyperfine coupling constants (shfcc), were the 6-
and 5-coordinated complexes. These two types of Hb-NO were generated
in a dose-dependent manner in the blood after intraperitoneal administ
ration of 1.5-6 mg of GTN. At the higher dose of GTN (6 mg), the 6-coo
rdinated complex was the major species generated initially, but within
10 min, the 5-coordinated complex increased time-dependently. Quantit
ative analysis of Hb-NO revealed that when GTN 0.3 mg and 0.6 mg was a
dministered sublingually in rats, the concentration of Hb-NO observed
in rat blood was 30% higher than the estimated concentration of GTN. T
he methemoglobin and peroxide complex of hemoglobin were observed in t
he blood incubated with GTN at 37 degrees C. These results suggest tha
t the function of GTN was related to oxidative stress with the generat
ion of W-NO. Therefore, monitoring of Hb-NO levels may be useful as an
indicator of the function of various vasodilators.