Brain Liver Intestine Na Channel (BLINaC) is an ion channel of the DEG/ENaC gene family with unknown function (ref. 1). In rodents, the blinac mRNA is expressed mainly in brain, liver, and intestine and to a lesser extent in kidney and lung (ref. 1); in humans, it is mainly expressed in the small intestine (ref. 2). To explore the expression of the BLINaC protein in these tissues, we generated a polyclonal antibody against mouse BLINaC, which recognizes an antigen of the correct size in Western blots. We currently use this antibody to determine the cellular expression pattern of BLINaC, in particular in the GI tract. Functional expression of rat BLINaC (rBLINaC) in Xenopus oocytes leads to small unselective currents that are only weakly sensitive to amiloride (ref. 1). rBLINaC is potently inhibited by micromolar concentrations of extracellular Ca2+ (Ki = 10 ± 1.5 μM) and removal of Ca2+ leads to robust currents and increases Na+ selectivity of the ion pore (ref. 3). Strikingly, the species ortholog from mouse (mBLINaC) has an almost 250-fold lower Ca2+ affinity than rBLINaC (Ki = 2.3 ± 0.2 mM), rendering mBLINaC constitutively active at physiological Ca2+ concentrations (ref. 3). In addition, mBLINaC is more selective for Na+ and has a 700-fold higher amiloride affinity than rBLINaC (Ki = 7.1 ± 0.9 μM compared with 6.4 ± 1.7 mM) (ref. 3). A single amino acid in the extracellular domain determines these profound species differences (ref. 3). These results suggest that rBLINaC is opened by an unknown ligand whereas mBLINaC is a constitutively open epithelial Na+ channel. The reason for this species difference is still enigmatic. Recently, we identified the fenamate flufenamic acid (FFA) and related compounds as agonists of rBLINaC. Application of millimolar concentrations of FFA to rBLINaC expressing oocytes induces a robust, Na+-selective current, which is partially blocked by amiloride. We also discovered that rBLINaC and mBLINaC, similar to the related acid sensing ion channels (ASICs) but in contrast to the epithelial Na+ channel ENaC, are inhibited by micromolar concentrations of diarylamidines and nafamostat. Thus, we identified pharmacological tools that will help to characterize the function of BLINaC in native tissues.