Fig. 8.

Model of nongenomic signaling of aldosterone in mouse OMCD intercalated cells to stimulate H⁺-ATPase activity. Aldosterone stimulates H⁺-ATPase activity through a major pathway requiring G_αq proteins, phospholipase C, intracellular Ca²⁺, PKC, and ERK1/2. A second interlinked pathway involves cAMP and PKA. The PKA-dependent pathway is likely upstream of PKC and ERK1/2 because inhibition of this pathway blocks the cAMP/PKA-dependent stimulation of H⁺-ATPase activity. Chelation of Ca²⁺ may interfere at several stages because Ca²⁺ may be involved in stimulation of PKC isoforms as well as in the exocytic insertion of H⁺-ATPases into the membrane, which has been shown earlier to occur during stimulation of H⁺-ATPase activity (58, 75). Inhibitors and activators of signaling molecules used in this study are shown in italics.