Modifications of Somatosensory Evoked Cortical Potentials during Hypoxia in the Awake Rabbit
Bicher et al. (1971, 1973) evidenced that the decrease of tissue pO2 in the cortex of the cat under nitrogen breathing was followed by an increase of this pO2. The phenomenon is accompanied by an increase in cerebral blood flow and a blocking of the action potentials registered at the prefrontal level of the cortex. Bicher (1974) postulated that the increase in tissue pO2 is due to two compensatory autoregulatory mechanisms; firstly local vasodilation and secondly an active inhibition of the neuronal discharge which decreases the oxygen consumption by limiting the sodium influx into the cell and thus reducing the sodium/ potassium pump energy expenditure, although it is generally admitted that oxygen deficiency causes a decrease of the activity of the pump with progressive cell membrane depolarization. It is well Known indeed that the activity of the nervous system is rapidly abolished by anoxia. Lack of oxygen suppresses both the unitary discharge of the cells and even to a greater extent the synaptic transmission. In the present investigation the modifications of the somatosensory evoked potentials in the unrestrained awake rabbit were studied during hypoxia of the moderate (12 %) and severe (6.5 %) type.
KeywordsSevere Hypoxia Unitary Discharge Moderate Hypoxia Sodium Influx Belgium Introduction
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