8-Br-cAMP (1 mmol/L, 30 min), 8-Br-cGMP (1 mmol/L, 30 min), or both 8-Br-cAMP+8-Br-cGMP significantly inhibits NHE3-mediated Na+ influx. *P<0.05 vs. VEH. The PP2A inhibitor okadaic acid (OA, 10 nmol/L) blocks the inhibition of NHE3-mediated Na+ influx caused by 8-Br-cAMP, 8-Br-cGMP, or 8-Br-cAMP+8-Br-cAMP. #P<0.05 vs. 8-Br-cAMP, 8-Br-cGMP, or 8-Br-cAMP+8-Br-cAMP.