The Effect of Hco₃⁻ on the Swelling and Ion Uptake of Monkey Cerebral Cortex Under Conditions of Raised Extracellular Potassium

Increasing the HCO 3 − concentration of incubation media containing raised K + concentrations (18‐71 mm) caused increased swelling of monkey cerebral cortex slices. This swelling was mainly associated with increased intracellular levels of Na + and Cl − ions. It was independent of the type of buffer used and was not a result of the increased Na + concentration in the media due to added HCO 3 − or the increased osmolarity. The levels also were unaffected by alteration of the pH in the range of 6·9‐ 7·8 or pCO 2 in the range of 3–81 mm Hg. The anatomical locus of this HCO 3 − stimulated swelling appeared in electron micrographs to be an expanded glial compartment. The significance of these findings is discussed in terms of the transport processes involved and the role of glial cells in maintaining correct cerebro‐cortical ion balances under normal and pathological conditions.