title: Oximetry in cells and tissues using a nitroxide-liposome system.
abstract: In order to avoid the complication of reduction of nitroxides in biological media during oxygen measurements, liposomes containing a water-soluble nitroxide, 2,2,6,6-tetramethyl-piperidine-N-oxyl-4-trimethylammonium (Cat1), were used in studies of oxygen consumption by thymus-bone-marrow cells. The superhyperfine structure of Cat1 contained in liposomes was found to be sensitive to oxygen concentration in a fashion similar to that of free Cat1. Measurements of cellular respiration using Cat1 contained in liposomes agreed well with the results obtained using free Cat1. Using this nitroxide-liposome system, the respiration of liver slices was measured successfully, whereas such measurements using free cat1 were complicated by rapid reduction of the nitroxide. This nitroxide-liposome system also could be used in conjunction with a membrane permeable nitroxide and an extracellular broadening agent to measure intracellular and extracellular oxygen concentrations simultaneously.
authors.affiliation: College of Medicine, Department of Medicine, University of Illinois, Urbana 61801.
authors.forename: H C
authors.initials: HC
authors.lastname: Chan
authors.forename: J F
authors.initials: JF
authors.lastname: Glockner
authors.forename: H M
authors.initials: HM
authors.lastname: Swartz
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000378:metabolism*; D002478:Cells, Cultured; D003497:Cyclic N-Oxides; D004578:Electron Spin Resonance Spectroscopy; D007202:Indicators and Reagents; D008081:Liposomes; D051379:Mice; D010084:Oxidation-Reduction; D010092:Oximetry / Q000379:methods*; D010101:Oxygen Consumption; D013113:Spin Labels; D013950:Thymus Gland / Q000378:metabolism*
chemical_list: D003497:Cyclic N-Oxides; D007202:Indicators and Reagents; D008081:Liposomes; D013113:Spin Labels; C051599:4-(N,N,N-trimethylamino)-2,2,6,6-tetramethylpiperidine-1-oxyl