Transient receptor potential polycystin-L (TRPP3) is a member of the TRP superfamily of cation channels that is localized to a subset of taste receptor cells in the tongue and to neurons surrounding the central canal of the spinal cord. Phenamil is a second generation analog of amiloride (hydrochloride) , the prototypical epithelial sodium channel (ENaC) blocker that inhibits TRPP3-mediated Ca2+-activated currents with an IC50 value of 0.14 μM. It is also known to inhibit ENaC (IC50 = 10 nM). ENaC blockers such as phenamil have been proposed as a therapy to restore mucus clearance in cystic fibrosis airways. Phenamil inhibits active sodium transport of human and ovine bronchial epithelial cells with IC50 values of 75 and 116 nM, respectively.
