title: Real-time, in vivo determination of dynamic changes in lung and heart tissue oxygenation using EPR oximetry.
abstract: The use of electron paramagnetic resonance (EPR) oximetry for oxygen measurements in deep tissues (>1 cm) is challenging due to the limited penetration depth of the microwave energy. To overcome this limitation, implantable resonators, having a small (0.5 mm diameter) sensory loop containing the oxygen-sensing paramagnetic material connected by a pair of twisted copper wire to a coupling loop (8-10 mm diameter), have been developed, which enable repeated measurements of deep-tissue oxygen levels (pO2, partial pressure of oxygen) in the brain and tumors of rodents. In this study, we have demonstrated the feasibility of measuring dynamic changes in pO2 in the heart and lung of rats using deep-tissue implantable oxygen sensors. The sensory loop of the resonator contained lithium octa-n-butoxynaphthalocyanine (LiNc-BuO) crystals embedded in polydimethylsiloxane (PDMS) polymer and was implanted in the myocardial tissue or lung pleura. The external coupling loop was secured subcutaneously above chest. The rats were exposed to different breathing gas mixtures while undergoing EPR measurements. The results demonstrated that implantable oxygen sensors provide reliable measurements of pO2 in deep tissues such as heart and lung under adverse conditions of cardiac and respiratory motions.
authors.affiliation: Department of Internal Medicine, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA.
authors.forename: Brian K
authors.initials: BK
authors.lastname: Rivera
authors.affiliation: Department of Internal Medicine, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA.
authors.forename: Shan K
authors.initials: SK
authors.lastname: Naidu
authors.affiliation: Department of Internal Medicine, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA.
authors.forename: Kamal
authors.initials: K
authors.lastname: Subramanian
authors.affiliation: Department of Internal Medicine, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Joseph
authors.affiliation: EPR Center for the Study of Viable Systems, Department of Radiology, Geisel School of Medicine at Dartmouth, 48 Lafayette Street, Lebanon, NH, 03766, USA.
authors.forename: Huagang
authors.initials: H
authors.lastname: Hou
authors.affiliation: EPR Center for the Study of Viable Systems, Department of Radiology, Geisel School of Medicine at Dartmouth, 48 Lafayette Street, Lebanon, NH, 03766, USA.
authors.forename: Nadeem
authors.initials: N
authors.lastname: Khan
authors.affiliation: EPR Center for the Study of Viable Systems, The Geisel School of Medicine at Dartmouth, Lebanon, NH, USA.
authors.forename: Harold M
authors.initials: HM
authors.lastname: Swartz
authors.affiliation: EPR Center for the Study of Viable Systems, Department of Radiology, Geisel School of Medicine at Dartmouth, 48 Lafayette Street, Lebanon, NH, 03766, USA. Periannan.Kuppusamy@Dartmouth.edu.
authors.forename: Periannan
authors.initials: P
authors.lastname: Kuppusamy
mesh_terms: D000818:Animals; D004129:Dimethylpolysiloxanes; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D008168:Lung / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004129:Dimethylpolysiloxanes; C013830:baysilon; D010100:Oxygen
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