VU0134992 hydrochloride is the first subtype-preferring, orally active and selective Kir4.1 potassium channel pore blocker, with an IC50 of 0.97 μM. VU0134992 hydrochloride is 9-fold selective for homomeric Kir4.1 over Kir4.1/5.1 concatemeric channels (IC50=9 μM) at -120 mV.