ON THE CELLULAR-LOCALIZATION AND DISTRIBUTION OF CARBONIC-ANHYDRASE-II IMMUNOREACTIVITY IN THE RAT-BRAIN

Evidence is provided that carbonic anhydrase-II is localized in the ce ntral nervous system to wide spread systems of oligodendrocytes and re stricted astroglia populations, involving both fiber bundles and neuro pil. It is suggested that CO, formed in activated axons may, via carbo nic anhydrase-II, give rise to protons controlling the excitability of surrounding neuropil. Thus, CO2 may represent an important, highly di ffusible, signal in brain, involved in the tonic control of neuronal a ctivity.