Polarographic measurements of the oxygen pressure performed simultaneously with optical measurements of the redox state of the respiratory chain in suspensions of mitochondria under steady-state conditions at low oxygen tensions
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Polarographic measurements were performed in respiring suspensions of mitochondria with membrane-covered platinum electrodes, using an optical cuvette which was provided with a Teflon window located parallel to the light path. When gases containing different amounts of oxygen were passing before the Teflon window, then in stirred probes the oxygen which had been consumed by respiration, could be replaced and steady-state conditions could be established with respect to oxygen pressure.
Simultaneous measurements of the redox state of cytochrome a+a3 with the dual wavelength spectrophotometer, or of the fluorescence of flavin and NADH with an additional fluorescence device, showed that the oxidation of mitochondria was achieved at oxygen pressures below the range (0.05 Torr oxygen pressure) which can be measured with the polarographic method.
Key wordsOxygen Uptake of Mitochondria CriticalPo2 Redox State of the Respiratory Chain
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