Background:

Sodium-hydrogen exchangers (NHE) are involved in maintaining sodium and pH balance in a variety of tissues. They are also known as sodium-hydrogen antiporters and solute carrier family 9 members. 5-(N-ethyl-N-isopropyl)-Amiloride (EIPA) is a potent inhibitor of several NHE isoforms, inhibiting NHE1, NHE2, NHE3, and NHE5 with Ki values of 0.02, 0.5, 2.4, and 0.42 μM, respectively[1],[2] It less effectively inhibits NHE4 (IC50 ≥10 μM).[1] EIPA is commonly used at a concentration of 5-10 μM to inhibit cellular HNE activity.[3],[4]

Reference:
[1]. Masereel, B., Pochet, L., and Laeckmann, D. An overview of inhibitors of Na+/H+ exchanger Eur. J. Med. Chem. 38(6), 547-554 (2003).
[2]. Attaphitaya, S., Park, K., and Melvin, J.E. Molecular cloning and functional expression of a rat Na+/H+ exchanger (NHE5) highly expressed in brain The Journal of Biological Chemisty 274(7), 4383-4388 (1999).
[3]. Hwang, S.M., Koo, N.Y., Jin, M., et al. Intracellular acidification is associated with changes in free cytosolic calcium and inhibition of action potentials in rat trigeminal ganglion The Journal of Biological Chemisty 286(3), 1719-1729 (2011).[4]. Xue, L., Aihara, E., Wang, T.C., et al. Trefoil factor 2 requires Na/H exchanger 2 activity to enhance mouse gastric epithelial repair The Journal of Biological Chemisty 286(44), 38375-38382 (2011).