Guanine-induced inhibition of renal Na+-ATPase activity: Evidence for the involvement of the Gi protein-coupled receptor

► Guanine binds to a DPCPX-sensitive receptor in proximal tubule basolateral membrane. ► Guanine promotes the activation of Gi protein leading to a decrease in cAMP level. ► Guanine decreases Na+-ATPase activity in isolated basolateral membrane. ► These events indicate a role of guanine on the modulation of renal sodium excretion.