VU 0240551 is a selective, small-molecule antagonist of the neuronal K-Cl cotransporter KCC2, exhibiting an IC50 of 560 nM. It also demonstrates off-target activity by inhibiting L-type calcium channels and the hERG potassium channel. This compound is utilized in neuroscience research to investigate GABAergic signaling, neuronal excitability, and related pathophysiology in both cellular and animal models.