FIG. 3.

Regulation of Ca²⁺ influx by H₂S. H₂S enhances the activity of NMDA receptors activated by the neurotransmitter glutamate and thereby increases Ca²⁺ influx in neurons. H₂S activates TRP channels to increase Ca²⁺ influx in astrocytes. In contrast, in retinal neurons, H₂S suppresses Ca²⁺ influx by activating V-ATPase, which releases H⁺ to suppress Ca²⁺ channels. NMDA, N-methyl-d-aspartate; TRP, transient receptor potential; V-ATPase, vacuolar-type proton ATPase.