Rat hippocampal slices need bicarbonate for the recovery of synaptic transmission after anoxia

The purpose of this study was to see how the nominal removal of bicarbonate (HCO(-)(3)) from the extracellular space of brain tissue influenced recovery of brain tissue from anoxia. Removal of HCO(-)(3) in HEPES-buffered artificial cerebrospinal fluid (aCSF) inhibited almost completely recovery of synaptic transmission in hippocampal slices after anoxia. Altered pH did not contribute to this finding because adjusting intracellular (pH(i)) and extracellular (pH(o)) pH to control levels did not reduce the effect of HCO(-)(3) removal. Our results suggest that HCO(-)(3) levels are important in determining the extent of anoxic or ischemic brain injury.