Fig. 6.

Membrane molecular pathways of Na⁺ signalling in astrocytes. Influx of Na⁺ occurs though (i) Na⁺-permeable channels which include ionotropic receptors (AMPAR, NMDAR, P2XR: AMPA, NMDA glutamate receptors and ionotropic purinoceptors, respectively); channels of the transient receptor potential (TRP) family (TRPC1/4/5 channels that operate as a part of store-operated Ca²⁺ entry and hence generate Na⁺ influx in response to the depletion of endoplasmic reticulum Ca²⁺ stores; as well as TRPA1 and TRPV4 channels); voltage-dependent Na_v channels and [Na⁺]_o-activated Na_x channels; (ii) through Na⁺-dependent SLC transporters that include excitatory amino acid transporters EAAT1,2, GABA transporters GAT 1,3, glycine transporters GlyT, noradrenaline transporters NET and concentrative adenosine transporters CNT2,3. The main pathway for Na⁺ exit is provided by Na⁺-K⁺ pump, NKA. The Na⁺-Ca²⁺ exchanger NCX fluctuates between forward and reverse modes and couples Na⁺ and Ca²⁺ signalling. Other abbreivations as in Fig. 5. (Reproduced with permission from Verkhratsky et al. (2020))