Figure 3.

Control of sodium and water transport by vasopressin in CD principal cells. The peptide hormone AVP binds to basolateral V2 receptors coupled to the activation of adenylyl cyclase via protein Gαs (Gαs). Generated cAMP binds to PKA regulatory subunits leading to release and activation of PKA catalytic subunit (PKAc) that phosphorylates a subset of substrates. PKA activation induces both post-transcriptional effects such as activation of ENaC and Na⁺,K⁺-ATPase as well as translocation of AQP2 water channels, and transcriptional effects such as increased AQP2 and ENaC subunits mRNA expression.