CORTICAL CO2 TENSION AND NEURONAL EXCITABILITY,
Abstract
Changes in the excitability of cortical cells were tested by micro-iontophoresis of L-glutamate during hypercapnia, recording simultaneously the cortical PCO2. Many cells clearly reacted to even small changes in PCO2. Moderate doses of CO2 led to both excitation and depression. With relatively low concentrations of inspired CO2 (<10%) the relative importance of excitant and depressant effects varied between cells and between different animals; with strong doses of CO2 (>10%) the depressant action was always predominant. CO2 probably acts directly on the cortex. Cortical responses evoked by peripheral stimulation were also examined; moderate hypercapnia depressed the evoked firing of units, but had relatively little effect on the slow-wave responses. Under chloralose anaesthesia, slow waves were very much potentiated by strong hypercapnia. Membrane potentials of cortical cells showed a consistent tendency towards hyperpolarization during hypercapnia and a sharp depolarization when PCO2 fell again. These changes in resting potential may account for some of the observed variations in excitability. Spinal neurones appear to be less sensitive than cortical neurones to variations in PCO2. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 23, 1964
- Accession Number
- AD0615075
Entities
People
- B. K. Siesjo
- K. Krnjevic
- Mirjana Randic
Organizations
- Lund University