Relations Between Po2 and Neuronal Activity in Hippocampal Slices
It is well known that the oxygen supply of the brain is characterized by typical profiles of Po2 (PtO2) in the tissue (Lübbers, 1969) and that the function of the CNS widely depends on an adequate distribution of PtO2. Hyperoxic PtO2 values, on the one hand, can induce seizures (cf. Bean, 1945; Lehmenkühler et al., 1978). During hypoxia, on the other hand, Speckmann and Caspers (1974) observed a depolarization of neurons in the spinal cord and in the brain cortex which was accompanied by a transient rise of neuronal activity until spike generation was blocked. Different mechanisms may contribute to this dependency of neuronal functions on Po2. (i) Yamamoto and Kurokawa (1970) described that hypoxia modified the energy state of neurons in vitro, (ii) Vyskocil et al. (1972), Morris (1974), Silver (1977) and Lehmenkühler et al. (1981) have shown that the oxygen deficiency alters the ionic milieu of the extracellular space which may be due to neuronal and/or glial dysfunctions as well as to changes of transport rates of ions via microcirculation. (iii) Finally, synaptic inputs e.g. from chemoreceptors can alter the neuronal activity. As a whole, during changes of Po2 neurons in vivo are affected by a great number of factors which can hardly be controlled simultaneously.
KeywordsNeuronal Activity Hippocampal Slice Rest Membrane Potential Membrane Resistance Potassium Activity
Unable to display preview. Download preview PDF.
- Bean, J.W., 1945, Effects of oxygen at increased pressure, Physiol, Rev., 25: 1–147.Google Scholar
- Bingmann, D., and Kolde, G., 1981, Reactions of neurons in vitro to changes of Po2 in the bath solution, Pflügers Arch., 391: R32.Google Scholar
- Bingmann, D., Kolde, G., and Speckmann, E.-J., 1982, Effects of elevated Po2 values in the superfusate on the neural activity in hippocampal slices, in; “Physiology and Pharmacology of Epileptogenic Phenomena”, M.R. Klee, H.B. Lux, E.-J. Speckmann, eds., Raven Press, New York, pp. 97–104.Google Scholar
- Gallego, R., and Belmonte, C, 1981, Electrical properties of petrosal ganglion chemoreceptor cells, in: “Arterial Chemo-receptors”, C. Belmonte, D.J. Pallot, H. Acker, S. Fidone, eds., Leicester University Press, Leicester, pp. 392–399.Google Scholar
- Hansen, A.J., Jahnsen, H., and Hounsgaard, J.B., 1979, Influence of hypoxia on hippocampal nerve cells in vitro, Acta Physiol. Scand., 473: 55.Google Scholar
- Lehmenkühler, A., Bingmann, D., Lange-Asschenfeldt, H., and Berges, D., 1978, Oxygen pressure and ictal activity in the cerebral cortex of artificially ventilated rats during exposure to oxygen high pressure, in: “Oxygen Transport to Tissue III”, I.A. Silver, M. Erecinska and H.I. Bicher, eds., Plenum Press, New York, pp. 679–685.CrossRefGoogle Scholar
- Lehmenkühler, A., Caspers, H., and Speckamnn, E.-J., 1976, A method for simultaneous measurement of bioelectrical activity and local Po2 in the CNS, in: “Oxygen Transport to Tissue II”, J. Grote, D. Reneau and G. Thews, eds., Plenum Press, New York, pp. 3–7.Google Scholar
- Lehmenkühler, A., Zidek, W., Staschen, M., and Caspers, H., 1981, Cortical pH and pCa in relation to DC potential shifts during spreading depression and asphyxiation, in.: “Ion-Selective Microelectrodes and Their Use in Excitable Tissues”, L. Vyklicky, E.S. Ykova, P. Huik, eds., Plenum Press, New York, pp. 225–230.CrossRefGoogle Scholar
- Lübbers, D.W., 1969, The meaning of the tissue oxygen distribution curve and its measurements by means of Pt-electrodes, in: “Oxygen Pressure Recording in Gases, Fluids and Tissues”, F. Kreuzer and H. Herzog, eds., Karger, Basel, pp. 112–123.Google Scholar
- Speckmann, E.-J., and Caspers, H., 1974, The effects of O2 and CO2 tensions in the nervous tissue on neuronal activity and DC-potentials, in: “Handbook of Electroencephalography and Clinical Neurophysiology II”, A. Rémond, ed., Elsevier, AmsterdamLondon-New York, pp. 71–89.Google Scholar
- Staschen, M., Zidek, W., Lehmenkühler, A., and Caspers, H., 1981, Changes of extracellular ion activities (K+, Na+, Ca++, H+, CI−) in relation to cortical DC-potential shifts during reversible asphyxia, Pflügers Arch., 389: R33.Google Scholar
- Yamamoto, C, and Kurokawa, M., 1970, Synaptic potentials recorded in brain slices and their modification by changes in the level of tissue ATP, Brain Res., 10: 159–170.Google Scholar