Figure 3. Known interactions between H₂S, CO, and NO signalling pathways.

Each gasotransmitter is capable of regulating the other two. Pointed arrows represent a stimulatory effect. Flat-headed arrows indicate an inhibitory effect. H₂S, Hydrogen sulfide; NO, Nitric oxide; CO, Carbon monoxide; CBS, Cystathionine-β-synthase; CSE, Cystathionine-γ-lyase; MPST, 3-Mercaptopyruvate sulfurtransferase; eNOS, Endothelial NO synthase; HO, Heme oxygenase; sGC, Soluble guanylyl cyclase; PKG, Protein kinase G; cGMP, Cyclic guanosine monophosphate.