BA6b9 is an allosteric inhibitor targeting the SK4 channel via the CaM-PIP2 binding domain. It interacts with two critical residues, Arg191 and His192, located in the S4-S5 linker to inhibit the SK4 channel, with an IC50 of 8.6 μM (WT SK4). BA6b9 significantly prolongs the effective refractory period (ERP) of the atria and atrioventricular node in isolated rat hearts, reducing the induction of atrial fibrillation (AF), highlighting its potential for arrhythmia research.

BA6b9 (10 μM) 通过提高Ca 2+ 激活的EC 50，从65 nM增至435 nM，显著抑制Ca 2+ 激活的SK4通道。此外，在重量为200-250 g的成年雄性Sprague-Dawley大鼠的Langendorff分离心脏模型实验中，BA6b9引发心率下降、PR间期延长以及心房和房室结有效不应期(ERP)的延长，并有效抑制由卡巴胆碱引起的心房颤动(AF)。