Development of a Method for Measuring Oxyngen Concentration in Biological Systems by Means of ESR

点击翻译按钮获取中文摘要

Active charcoal, fusinite and a stable nitroxide radical, TEMPONE, were examined for suitability as a probe for the measurement of dissolved oxygen concentrations in cells and in tissues using ESR.Fusinite and activated charcoal were very slow in reaching an equilibrium. On the other hand, the equilibrium was rapidly obtained with ESR spectrum of TEMPONE although its dependence on oxygen concentrations was smaller. Perdeuterted analog of TEMPONE (TEMPONE-d_<16>) is most useful since its ESR signals are narrower so that it gives higher sensitivity and higher accuracy in the determination of linewidth or peak height.Biological Membranes are permeable to TEMPONE-d_<16>. Therefore, it quickly distributes both inside and outside cells. Broadening extracellular signals with paramagnetic ions such as oxalatochromate (III) leaves intracellular signals intact and hence enables to measure intracellular oxygen concentrations. Nitroxide radicals are usually subject to redox reactions inside cells. This is very useful to monitor activities of redox enzymes while it necessitates one to measure linewidths, not peak heights, for oxymetry.Experiment with a mouse whole-body was performed using as L-band spectrometer. An aqueous solution of TEMPONE-d_<16> is sealed in a small TPX tube which is permeable to gas. The probe was incorporated in a mouse peritoneal cavity by operation. A satisfactory S/N ratio was obtained after a fine tuning of the loop-gap resonator. Depending on the change in oxygen concentrations of respiratory gas, peak heights of the ESR signal changed. The peak height was smaller with higher oxygen concentrations and vice versa.