A Method for Simultaneous Measurements of Bioelectric Activity and Local Tissue PO2 in the CNS
Previous investigations have shown that recordings of tissue PO2 in central nervous structures by means of the Polarographic method may be considerably distorted, if Pt-microelectrodes are used in connection with a remote reference point (4). Such distortions are due to DC potentials generated by neural networks of the CNS in a variety of physiological and pathological conditions (c.f. 2). The bioelectric DC potentials interfere with the polarizing voltage in the Polarographic circuit and can simulate changes in PO2, since a sufficient Polarographie step in the current-voltage curves of Pt-microelectrodes is often missing. To avoid this source of error, a recording device has to be used which allows either to reduce the pick up of DC potentials to a minimum or to compensate for them. These requirements are fulfilled by concentric or double micro-electrodes in which the AgAgCl-reference is coupled to the active Pt-tip at a distance of a few microns (c.f. 4). Meanwhile various technical versions of such electrode arrangements have proved their reliability (s. also 1).
KeywordsPolarize Voltage Bioelectric Activity High Oxygen Pressure Graphic Circuit Polarographic Current
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