DiBAC₄(3) hits a "sweet spot" for the activation of arterial large-conductance Ca²⁺-activated potassium channels independently of the β₁-subunit.

The voltage-sensitive dye bis-(1,3-dibutylbarbituric acid)trimethine oxonol [DiBAC₄(3)] has been reported as a novel large-conductance Ca²⁺-activated K⁺ (BK) channel activator with selectivity for its β₁- or β₄-subunits. In arterial smooth muscle, BK channels are formed by a pore-forming α-subunit and a smooth muscle-abundant regulatory β₁-subunit. This tissue specificity has driven extensive pharmacological research aimed at regulating arterial tone.