FIGURE 2.

Ionic currents between neurons, astrocytes, and the extracellular space. There are five K⁺ currents (indicated here by a single arrow): KDR (delayed rectifier), BK (noninactivating calcium-dependent), KM (noninactivating muscarinic), SK (voltage-independent Ca²⁺-dependent), and IK (K2 Ca²⁺-dependent); two Na⁺ currents (indicated by a single arrow): NaF (fast Na⁺) and NaP (persistent Na⁺); one Ca²⁺ current (high-voltage activated, P-type) and the NMDA receptor currents, present only in the neurons. The pumps and exchangers are the Cl⁻, Ca²⁺, and Na⁺/K⁺ pumps, the Na⁺/Ca²⁺ exchanger, and the K⁺/Cl⁻ and Na⁺/K⁺/Cl⁻ transporters, the last one present only in the astrocytes. The remaining currents are the K⁺, Na⁺, Ca²⁺, and Cl⁻ leak currents. The detailed equations and parameter values for all these currents are given in Data S1.