Evaluation of systemic blood NO dynamics by EPR spectroscopy: HbNO as an endogenous index of NO.
The measurement of hemoglobin-nitric oxide (NO) adduct (HbNO) in whole blood by the electron paramagnetic resonance (EPR) method seems relevant for the assessment of systemic NO levels. However, ceruloplasmin and unknown radical species overlap the same magnetic field as that of HbNO. To reveal the EPR spectrum of HbNO, we then introduced the EPR signal subtraction method, which is based on the computer-assisted subtraction of the digitized EPR spectrum of HbNO-depleted blood from that of sample blood using the software. Rats were treated with N(omega)-nitro-L-arginine methyl ester (L-NAME; 120 mg. kg-1. day-1) for 1 wk to obtain HbNO-depleted blood. When this method was applied to the analysis of untreated fresh whole blood, the five-coordinate state of HbNO was observed. HbNO concentration in pentobarbital-anesthetized rats was augmented (change in [HbNO] = 1.6-5.5 microM) by infusion of L-arginine (0.2-0.6 g/kg) but not D-arginine. Using this method, we attempted to evaluate the effects of temocapril on HbNO dynamics in an L-NAME-induced rat endothelial dysfunction model. The oral administration of L-NAME for 2 wk induced a serious hypertension, and the HbNO concentration was reduced (change in [HbNO] = 5.7 microM). Coadministration of temocapril dose dependently improved both changes in blood pressure and the systemic HbNO concentration. In this study, we succeeded in measuring the blood HbNO level as an index of NO by the EPR HbNO signal subtraction method. We also demonstrated that temocapril improves abnormalities of NO dynamics in L-NAME-induced endothelial dysfunction rats using the EPR HbNO signal subtraction method.
Kirima
Kazuyoshi
K
Department of Pharmacology, The University of Tokushima School of Medicine, 3-18-15 Kuramoto, Tokushima 770-8503, Japan.
Tsuchiya
Koichiro
K
Sei
Hiroyoshi
H
Hasegawa
Toyoshi
T
Shikishima
Michiyo
M
Motobayashi
Yuki
Y
Morita
Kyoji
K
Yoshizumi
Masanori
M
Tamaki
Toshiaki
T
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D002138:Calibration; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006454:Hemoglobins / Q000378:metabolism*; D006973:Hypertension / Q000139:chemically induced / Q000378:metabolism; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000097:blood*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013841:Thiazepines / Q000494:pharmacology
D000806:Angiotensin-Converting Enzyme Inhibitors; D004791:Enzyme Inhibitors; D006454:Hemoglobins; D013841:Thiazepines; D009569:Nitric Oxide; C055603:temocapril hydrochloride; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester