Real-time monitoring of drug-induced changes in the stomach acidity of living rats using improved pH-sensitive nitroxides and low-field EPR techniques

Potapenko, Dmitrii I.; Foster, Margaret A.; Lurie, David John; Kirilyuk, Igor A.; Hutchison, J.M.S.; Григорьев, И. А.; Bagryanskaya, Elena G.; Khramtsov, Valery V.

doi:10.1016/j.jmr.2006.06.002

Cited by 57 publications

(58 citation statements)

References 38 publications

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“…Fig. 12c demonstrates real-time measurements of the stomach acidity in living rats using 300 MHz EPR and IR6 probe (Potapenko et al, 2006). Long lifetime of the IR6 probe in vivo allows for monitoring drug-induced perturbation of stomach acidity and its normalization afterwards for periods of 1 h or longer, therefore supporting applicability of pH sensitive NRs to the studies of drug pharmacology and disease in living animals.…”

Section: In Vivo Ph Monitoring Using Ph-sensitive Nitroxidesmentioning

confidence: 88%

“…properties optimized for monitoring stomach acidity (Potapenko et al, 2006). The presence of bulky groups in the vicinity of the NO fragment enhanced IR6 stability towards reduction, resulting in about four fold increase of its lifetime in vivo compared with that for previously used IR3 (Gallez et al, 1996b;Foster et al, 2003).…”

Section: In Vivo Ph Monitoring Using Ph-sensitive Nitroxidesmentioning

confidence: 98%

“…Low-field EPR spectroscopy using spin pH probes has been shown to be a valuable tool for in vivo pH monitoring in organs and small animals such as rodents (Gallez et al, 1996b;Mader et al, 1996;Khramtsov et al, 2000;Foster et al, 2003;Potapenko et al, 2006;Bobko et al, 2012;Komarov et al, 2012). Figure 12a shows the structure of the nitroxide IR6 with The pH dependence of hyperfine splitting, aN, measured from 300 MHz EPR spectra of IR6.…”

Section: In Vivo Ph Monitoring Using Ph-sensitive Nitroxidesmentioning

confidence: 99%

“…(c) Changes in the stomach acidity of living rat measured by longitudinally detected EPR spectrometer operated at 304 MHz excitation frequency, after giving 3 ml of gavage containing 5 mM IR6 probe alone (□) or with 50 mM bicarbonate (•). From (Potapenko et al, 2006) with permission, copyright 2006, Elsevier Inc.…”

Section: In Vivo Ph Monitoring Using Ph-sensitive Nitroxidesmentioning

confidence: 99%

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In vivo Spectroscopy and Imaging of Nitroxide Probes

Khramtsov¹

2012

Nitroxides - Theory, Experiment and Applications

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Section: In Vivo Ph Monitoring Using Ph-sensitive Nitroxidesmentioning

confidence: 88%

Section: In Vivo Ph Monitoring Using Ph-sensitive Nitroxidesmentioning

confidence: 98%

Section: In Vivo Ph Monitoring Using Ph-sensitive Nitroxidesmentioning

confidence: 99%

Section: In Vivo Ph Monitoring Using Ph-sensitive Nitroxidesmentioning

confidence: 99%

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In vivo Spectroscopy and Imaging of Nitroxide Probes

Khramtsov¹

2012

Nitroxides - Theory, Experiment and Applications

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“…Note that at low EPR frequency, 563.2 MHz in Figure 14, the three lines of the spectrum are unequally spaced due to the Breit-Rabi effect (13,102).…”

Section: Fig 12 Redox Imaging Of Muscle In Bpvc-treated Mice By Usimentioning

confidence: 97%

In Vivo Application of Proton-Electron Double-Resonance Imaging

Kishimoto

Krishna

Khramtsov

et al. 2018

Antioxidants & Redox Signaling

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Significance: Proton-electron double-resonance imaging (PEDRI) employs electron paramagnetic resonance irradiation with low-field magnetic resonance imaging so that the electron spin polarization is transferred to nearby protons, resulting in higher signals. PEDRI provides information about free radical distribution and, indirectly, about the local microenvironment such as partial pressure of oxygen (pO 2 ), tissue permeability, redox status, and acid-base balance. Recent Advances: Local acid-base balance can be imaged by exploiting the different resonance frequency of radical probes between R and RH + forms. Redox status can also be imaged by using the loss of radical-related signal after reduction. These methods require optimized radical probes and pulse sequences. Critical Issues: High-power radio frequency irradiation is needed for optimum signal enhancement, which may be harmful to living tissue by unwanted heat deposition. Free radical probes differ depending on the purpose of PEDRI. Some probes are less effective for enhancing signal than others, which can reduce image quality. It is so far not possible to image endogenous radicals by PEDRI because low concentrations and broad line widths of the radicals lead to negligible signal enhancement. Future Directions: PEDRI has similarities with electron paramagnetic resonance imaging (EPRI) because both techniques observe the EPR signal, directly in the case of EPRI and indirectly with PEDRI. PEDRI provides information that is vital to research on homeostasis, development of diseases, or treatment responses in vivo. It is expected that the development of new EPR techniques will give insights into novel PEDRI applications and vice versa. Antioxid. Redox Signal. 28, 1345Signal. 28, -1364

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Electron Paramagnetic Resonance Imaging

Eaton

2011

Encyclopedia of Analytical Chemistry

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Unpaired electrons can be measured by their absorption of electromagnetic radiation when the energy level separations established by a magnetic field match the energy of the incident electromagnetic radiation (usually microwave or radio frequency). The measurement method is called electron paramagnetic resonance (EPR). The EPR methodology can be continuous‐wave (CW), pulsed, or rapid‐scan EPR. Since the paramagnetic species are commonly not uniformly distributed in the material studied, the spatial distribution can be discerned by performing the EPR measurement in a magnetic‐field gradient, such that different parts of the sample resonate at different strengths of the applied magnetic field. Performing EPR in a gradient field and then constructing a spatial image from the acquired EPR spectra is called EPR imaging, sometimes abbreviated to EPRI. The method is analogous to MRI, but with several differences in implementation due to differences in spectral line widths, relaxation times, and unpaired spin concentrations. The goal of EPRI is to determine why the spins are where they are. Applications are as diverse as understanding physiology, measuring O 2 concentration in tumors, and determining the distribution of radiation‐induced defect centers in solid materials.

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Real-time monitoring of drug-induced changes in the stomach acidity of living rats using improved pH-sensitive nitroxides and low-field EPR techniques

Cited by 57 publications

References 38 publications

In vivo Spectroscopy and Imaging of Nitroxide Probes

In vivo Spectroscopy and Imaging of Nitroxide Probes

In Vivo Application of Proton-Electron Double-Resonance Imaging

Electron Paramagnetic Resonance Imaging

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