Noninvasive in vivo determination of intracerebral oxygen concentration in rats by a longitudinally detected ESR (LODESR) technique

Yokoyama, Hidekatsu; Sato, Toshiyuki; Fukui, Kôichi; Itoh, Osamu; Ohya, Hiroaki; Akatsuka, Takao

doi:10.1002/mrm.10725

Cited by 1 publication

(2 citation statements)

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“…The nitroxyl radicals are well-known from electron-paramagnetic resonance (EPR) studies (Valgimigli et al 2001;Kuppusamy et al 2002;Hirayama et al 2003;Yokoyama et al 2004). They are small molecules, sensitive to redox status of biological samples ( Fig.…”

Section: Introductionmentioning

confidence: 99%

“…They are small molecules, sensitive to redox status of biological samples ( Fig. 1) and are usually used for tissue oxygen and redox mapping in vitro and in vivo (Valgimigli et al 2001;Kuppusamy et al 2002;Hirayama et al 2003;Yokoyama et al 2004;Hyodo et al 2006;Matsumoto et al 2006; Utsumi et al 2006). The paramagnetic nitroxyl radical could be reduced to diamagnetic hydroxylamine with loss of EPR signal and thus to serve as reduction sensor.…”

Section: Introductionmentioning

confidence: 99%

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EPR signal reduction kinetic of several nitroxyl derivatives in blood in vitro and in vivo

Zhelev¹,

Matsumoto²,

Gadjeva³

et al. 2009

gpb

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Abstract. The present study is focused on the mechanism(s) of electron-paramagnetic resonance (EPR) signal reduction kinetic of several nitroxyl radicals and nitroxyl-labeled anticancer drugs in physiological solutions in the context of their application for evaluation of oxidation/reduction status of blood and tissues -an important step in biomedical diagnostics and planning of therapy of many diseases. The nitroxyl derivatives were characterized with different size and water-solubility. Some of them are originally synthesized. In buffer, in the absence of reducing and oxidizing equivalents, the EPR signal intensity of all nitroxyls was constant with the time. In serum and cell cultured medium, in an absence of cells and in a negligible amount of reducing and oxidizing equivalents, there was no significant EPR signal reduction, too. In vitro (in freshly isolated blood samples), the EPR signal intensity was characterized with slow decrease within 30 min, presumably as a result of interaction between the nitroxyl derivative and blood cells. The EPR spectrum of hydrophobic nitroxyls showed a slight anisotropy in cell-containing solutions and it did not changed in non-cell physiological solutions. This suggests for a limited motion of more hydrophobic nitroxyls through their preferable location in cell membranes. In vivo (in the bloodstream of mice under anesthesia), the EPR signal reduction kinetic was characterized by two phases: i) a rapid enhancement within 30 s as a result of increasing of nitroxyl concentration in the bloodstream after its intravenous injection, followed by ii) a rapid decrease (~80-100%) within 2-5 min, presumably as a result of transportation of nitroxyl in the tissues. The hydrophobic nitroxyls were characterized with stronger and faster decrease in EPR signal intensity in the blood in vivo, as a result of their higher cell permeability, rapid clearance from the bloodstream and/or transportation in the surrounding tissues. The hydrophilic nitroxyls persist in the bloodstream (in their radical form) for a comparatively long time.The data suggest that the hydrophobic cell-permeable nitroxyl derivatives are most appropriate for evaluation of cell and tissue oxidation/reduction status, while the hydrophilic nitroxyls (impermeable for cell membranes or with very slow cell permeability) are most appropriate for evaluation of oxidation/reduction status of blood using EPR imaging.

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Section: Introductionmentioning

confidence: 99%