Figure 5. Syncytial coupling attenuates local elevated extracellular K⁺-induced V_M depolarization.

(A) Bath 23.5 mM high K⁺-induced V_M depolarization from an astrocyte and an NG2 glia, as indicated. (B) Summary of bath and local high [K⁺]_e induced V_M depolarization. (C) A 5 ms local high [K⁺]e was applied to a recorded astrocyte with an affected subdomain area monitored by SR101 included in the high [K⁺]_e solution (two sample t test). (D) A 5 ms local high [K⁺]_e puff induced V_M depolarization in an astrocyte and an NG2 glia. (E) Schematic illustration of V_M response to a high [K⁺]_e puff. In an uncoupled astrocyte, the V_M quickly depolarizes to the new elevated [K⁺]_e established E_M. Once V_M → E_M, the K⁺ uptake stops. In coupled astrocytes, the V_M remains close to a constant. This maintains the driving force, V_M − E_M, for a “sustained K⁺ uptake”. *P < 0.05, one way ANOVA test for comparison of the V_M depolarization between astrocytes and NG2 glia.