Measurement of PO2 in liver using EPR oximetry

With the use of India ink and lithium phthalocyanine (LiPc) as electron paramagnetic resonance (EPR) oximetry probes, the PO2 of the liver was investigated in mice. Because India ink was taken up by the Kupffer cells of the liver, the EPR signal of the India ink reflected the average PO2 in phagocytic vesicles of these cells. The mean value of PO2 in the Kupffer cells measured by India ink was 15.3 +/- 4.4 Torr in unanesthetized animals. LiPc was administered as a macroscopic crystal and therefore reflected the PO2 of the overall liver. The PO2 measured by LiPc was 23.4 +/- 4.4 Torr, which is consistent with the median value of 23.5 Torr reported previously with the use of an oxygen electrode. Anesthesia (injection of 60 mg/kg ip pentobarbital sodium) decreased the average PO2 in both Kupffer cells and the overall liver. The effects of perturbing the blood flow were studied by reversible blockage of the portal vein and hepatic artery in anesthetized mice; the PO2 in both Kupffer cells (measured with India ink) and in overall liver (measured with LiPc) decreased with obstruction of the blood flow and returned toward normal with reperfusion. These results indicate that the PO2 in different locations in the liver can be significantly different under both normal conditions and after perturbation by either anesthesia or ischemia. These results also demonstrate that EPR oximetry can provide sensitive measurements of PO2 in the liver in vivo under various conditions.

Download Full-text

Measurement of oxygen partial pressure, its control during hypoxia and hyperoxia, and its effect upon light emission in a bioluminescent elaterid larva

Journal of Experimental Biology ◽

10.1242/jeb.202.19.2631 ◽

1999 ◽

Vol 202 (19) ◽

pp. 2631-2638 ◽

Cited By ~ 2

Author(s):

G.S. Timmins ◽

C.A. Penatti ◽

E.J. Bechara ◽

H.M. Swartz

Keyword(s):

Partial Pressure ◽

Light Emission ◽

Threshold Value ◽

Respiratory Physiology ◽

Paramagnetic Resonance ◽

Epr Oximetry ◽

Electron Paramagnetic ◽

Long Term Measurement

This study investigates the respiratory physiology of bioluminescent larvae of Pyrearinus termitilluminans in relation to their tolerance to hypoxia and hyperoxia and to the supply of oxygen for bioluminescence. The partial pressure of oxygen (P(O2)) was measured within the bioluminescent prothorax by in vivo electron paramagnetic resonance (EPR) oximetry following acclimation of larvae to hypoxic, normoxic and hyperoxic (normobaric) atmospheres and during periods of bioluminescence (during normoxia). The P(O2) in the prothorax during exposure to an external P(O2) of 15.2, 160 and 760 mmHg was 10.3+/−2.6, 134+/−0.9 and 725+/−73 mmHg respectively (mean +/− s.d., N=5; 1 mmHg=0.1333 kPa). Oxygen supply to the larvae via gas exchange through the spiracles, measured by determining the rate of water loss, was also studied in the above atmospheres and was found not to be dependent upon P(O2). The data indicated that there is little to no active control of extracellular tissue P(O2) within the prothorax of these larvae. The reduction in prothorax P(O2) observed during either attack-response-provoked bioluminescence or sustained feeding-related bioluminescence in a normoxic atmosphere was variable, but fell within the range 10–25 mmHg. The effect of hypoxic atmospheres on bioluminescence was measured to estimate the intracellular P(O2) within the photocytes of the prothorax. Above a threshold value of 50–80 mmHg, bioluminescence was unaffected by P(O2). Below this threshold, an approximately linear relationship between P(O2) and bioluminescence was observed. Taken together with the extracellular P(O2) measurements, this suggests that control of P(O2) within the photocyte may occur. This work establishes that EPR oximetry is a valuable technique for long-term measurement of tissue P(O2) in insects and can provide valuable insights into their respiratory physiology. It also raises questions regarding the hypothesis that bioluminescence can have a significant antioxidative effect by reduction of prothorax P(O2)through oxygen consumption.

Download Full-text

Tissue Oxygen is Reduced in White Matter of Spontaneously Hypertensive-Stroke Prone Rats: A Longitudinal Study with Electron Paramagnetic Resonance

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2014.35 ◽

2014 ◽

Vol 34 (5) ◽

pp. 890-896 ◽

Cited By ~ 23

Author(s):

John Weaver ◽

Fakhreya Y Jalal ◽

Yi Yang ◽

Jeffrey Thompson ◽

Gary A Rosenberg ◽

...

Keyword(s):

Electron Paramagnetic Resonance ◽

White Matter ◽

Small Vessel Disease ◽

Tissue Oxygen ◽

Paramagnetic Resonance ◽

Spontaneously Hypertensive ◽

Brain Physiology ◽

Epr Oximetry ◽

Electron Paramagnetic

Small vessel disease is associated with white-matter (WM) magnetic resonance imaging (MRI) hyperintensities (WMHs) in patients with vascular cognitive impairment (VCI) and subsequent damage to the WM. Although WM is vulnerable to hypoxic-ischemic injury and O2 is critical in brain physiology, tissue O2 level in the WM has not been measured and explored in vivo. We hypothesized that spontaneously hypertensive stroke-prone rat (SHR/SP) fed a Japanese permissive diet (JPD) and subjected to unilateral carotid artery occlusion (UCAO), a model to study VCI, would lead to reduced tissue oxygen (pO2) in the deep WM. We tested this hypothesis by monitoring WM tissue pO2 using in vivo electron paramagnetic resonance (EPR) oximetry in SHR/SP rats over weeks before and after JPD/UCAO. The SHR/SP rats experienced an increase in WM pO2 from 9 to 12 weeks with a maximal 32% increase at week 12, followed by a dramatic decrease in WM pO2 to near hypoxic conditions during weeks 13 to 16 after JPD/UCAO. The decreased WM pO2 was accompanied with WM damage and hemorrhages surrounding microvessels. Our findings suggest that changes in WM pO2 may contribute to WM damage in SHR/SP rat model, and that EPR oximetry can monitor brain pO2 in the WM of small animals.

Download Full-text

Clinical Electron Paramagnetic Resonance (EPR) Oximetry Using India Ink

Advances in Experimental Medicine and Biology - Oxygen Transport to Tissue XXXI ◽

10.1007/978-1-4419-1241-1_21 ◽

2009 ◽

pp. 149-156 ◽

Cited By ~ 29

Author(s):

Benjamin B. Williams ◽

Nadeem Khan ◽

Bassem Zaki ◽

Alan Hartford ◽

Marc S. Ernstoff ◽

...

Keyword(s):

Electron Paramagnetic Resonance ◽

Paramagnetic Resonance ◽

India Ink ◽

Epr Oximetry ◽

Electron Paramagnetic

Download Full-text

ДИНИТРОЗИЛЬНЫЕ КОМПЛЕКСЫ ЖЕЛЕЗА C ТИОЛСОДЕРЖАЩИМИ ЛИГАНДАМИ ПРЕДСТАВЛЕНЫ В ЖИВЫХ ОРГАНИЗМАХ В ОСНОВНОМ ИХ БИЯДЕРНОЙ ФОРМОЙ

Биофизика ◽

10.31857/s0006302920060149 ◽

2020 ◽

Vol 65 (6) ◽

pp. 1142-1153

Author(s):

В.Д. Микоян ◽

◽

Е.Н. Бургова ◽

Р.Р. Бородулин ◽

А.Ф. Ванин ◽

...

Keyword(s):

Electron Paramagnetic Resonance ◽

Sodium Nitrite ◽

Iron Complexes ◽

Paramagnetic Resonance ◽

First Case ◽

Dinitrosyl Iron ◽

Electron Paramagnetic ◽

Dinitrosyl Complexes

The number of mononitrosyl iron complexes with diethyldithiocarbamate, formed in the liver of mice in vivo and in vitro after intraperitoneal injection of binuclear dinitrosyl iron complexes with N-acetyl-L-cysteine or glutathione, S-nitrosoglutathione, sodium nitrite or the vasodilating drug Isoket® was assessed by electron paramagnetic resonance (EPR). The number of the said complexes, in contrast to the complexes, formed after nitrite or Isoket administration, the level of which sharply increased after treatment of liver preparations with a strong reducing agent - dithionite, did not change in the presence of dithionite. It was concluded that, in the first case, EPR-detectable mononitrosyl iron complexes with diethyldithiocarbamate in the absence and presence of dithionite appeared as a result of the reaction of NO formed from nitrite with Fe2+-dieth- yldithiocarbamate and Fe3+-diethyldithiocarbamate complexes, respectively. In the second case, mononitrosyl iron complexes with diethyldithiocarbamate appeared as a result of the transition of iron-mononitosyl fragments from ready-made iron-dinitrosyl groups of binuclear dinitrosyl complexes, which is three to four times higher than the content of the mononuclear form of these complexes in the tissue...

Download Full-text

Photoreactivity of Hair Melanin from Different Skin Phototypes—Contribution of Melanin Subunits to the Pigments Photoreactive Properties

International Journal of Molecular Sciences ◽

10.3390/ijms22094465 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4465

Author(s):

Krystian Mokrzynski ◽

Shosuke Ito ◽

Kazumasa Wakamatsu ◽

Theodore G. Camenish ◽

Tadeusz Sarna ◽

...

Keyword(s):

Chemical Composition ◽

Singlet Oxygen ◽

Near Infrared ◽

Paramagnetic Resonance ◽

Time Resolved ◽

W Band ◽

Epr Oximetry ◽

X Band ◽

Hair Samples ◽

Electron Paramagnetic

Photoreactivity of melanin has become a major focus of research due to the postulated involvement of the pigment in UVA-induced melanoma. However, most of the hitherto studies were carried out using synthetic melanin models. Thus, photoreactivity of natural melanins is yet to be systematically analyzed. Here, we examined the photoreactive properties of natural melanins isolated from hair samples obtained from donors of different skin phototypes (I, II, III, and V). X-band and W-band electron paramagnetic resonance (EPR) spectroscopy was used to examine the paramagnetic properties of the pigments. Alkaline hydrogen peroxide degradation and hydroiodic acid hydrolysis were used to determine the chemical composition of the melanins. EPR oximetry and spin trapping were used to examine the oxygen photoconsumption and photo-induced formation of superoxide anion, and time-resolved near infrared phosphorescence was employed to determine the singlet oxygen photogeneration by the melanins. The efficiency of superoxide and singlet oxygen photogeneration was related to the chemical composition of the studied melanins. Melanins from blond and chestnut hair (phototypes II and III) exhibited highest photoreactivity of all examined pigments. Moreover, melanins of these phototypes showed highest quantum efficiency of singlet oxygen photogeneration at 332 nm and 365 nm supporting the postulate of the pigment contribution in UVA-induced melanoma.

Download Full-text