In vivo oximetry using a nitroxide-liposome system.
Liposomes containing the deuterated, charged, aqueous soluble nitroxide 4-trimethyl-ammonium-2,2,6,6-tetramethylpiperidine-d16-1-oxyl (d-Cat1) were used as probes to measure oxygen concentrations in vivo. Following intramuscular or intraperitoneal injection of the liposome suspension. ICR mice were placed over the surface probe of a low frequency (1.1 GHz) electron paramagnetic resonance (EPR) spectrometer. The linewidth of the deuterated nitroxide is sensitive to changes in the dissolved oxygen concentration: this parameter was calibrated separately so that linewidths measured in the injected mice could be converted into oxygen tensions. This technique detected substantial changes in pO2 as the oxygen content of the breathing gas was changed from 21 to 85 to 0%. Intravenous injection of the liposomes also is possible, and the liposomes accumulate in the liver and spleen, where detectable, oxygen-sensitive EPR signals can be measured.
Glockner
J F
JF
College of Medicine, Department of Medicine, University of Illinois, Urbana 61801.
Chan
H C
HC
Swartz
H M
HM
D000818:Animals; D002138:Calibration; D002245:Carbon Dioxide / Q000008:administration & dosage; D003497:Cyclic N-Oxides; D004337:Drug Carriers; D004355:Drug Stability; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation; D008081:Liposomes; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation; D051379:Mice; D008813:Mice, Inbred ICR; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000008:administration & dosage / Q000097:blood*; D013113:Spin Labels
D003497:Cyclic N-Oxides; D004337:Drug Carriers; D008081:Liposomes; D013113:Spin Labels; D002245:Carbon Dioxide; C051599:4-(N,N,N-trimethylamino)-2,2,6,6-tetramethylpiperidine-1-oxyl; D010100:Oxygen