FIGURE 9.

Superoxide (${\mathrm{O}}_2^{-}$) signaling in thick ascending limbs. Arrows indicate stimulation, and T-lines indicate inhibition. Dashed lines indicate that the complete signaling cascade is unknown. NADPH oxidase (NOX) is likely the primary source of ${\mathrm{O}}_2^{-}$ in thick ascending limbs but the isoform activated by a given stimulus may vary. NHE, Na⁺/H⁺ exchanger; NKCC2, Na⁺-K⁺-2Cl⁻ cotransporter type 2; PKCα, protein kinase Cα.