Mechanisms of K⁺-induced Glial Swelling

Abstract

The effect of high extracellular K⁺ (K⁺ _e) on glial swelling was analyzed in vitro employing C6 glioma cells or astrocytes obtained from primary culture. The cells were suspended in an incubation chamber with continuous control of pH, temperature, and PO₂. Cell swelling was quantified by flow cytometry. After a control period, the K⁺ _e level in the suspension medium was increased to 30 mM, with maintenance of isotonicity and normal pH. Elevation of K⁺ _e led to an increase in cell volume by 7%–10% within 12 min. This was followed by spontaneous normalization of volume although K⁺ _e remained increased. The K₊-induced glial swelling was prevented by ouabain or by inhibition of glycolysis using iodoacetate. The findings indicate that cell swelling from high K⁺ _e results from intracellular accumulation of this ion secondary to activation of Na⁺/K⁺-ATPase. Cell swelling under these conditions is supported by enhanced intracellular formation of lactic acid resulting from K⁺ _e-induced stimulation of anaerobic metabolism.

Supported by Deutsche Forschungsgemeinschaft ba 452/6–7