A recent study indicated that
apamin-sensitive current (I KAS, mediated by
apamin-sensitive
small conductance calcium-activated potassium channels subunits) density significantly increased in
heart failure and led to recurrent spontaneous
ventricular fibrillation. While the underlying molecular correlation with SK channels is still undetermined, we hypothesized that they are remodeled in HF and that
bisoprolol could reverse the remodeling. Volume-overload models were created on male Sprague-Dawley rats by producing an abdominal
arteriovenous fistula. Confocal microscopy, quantitative real-time PCR, and western blot were performed to investigate the expression of SK channels and observe the influence of β-blocker
bisoprolol on the expression of SK channels I KAS, and the effect of
bisoprolol on I KAS and the sensitivity of I KAS to [Ca(2+)]i at single isolated cells were also explored using whole-cell patch clamp techniques. SK channels were remodeled in HF rats, displaying the significant increase of SK1 and SK3 channel expression. After the treatment of HF rats with
bisoprolol, the expression of SK1 and SK3 channels was significantly downregulated, and
bisoprolol effectively downregulated I KAS density as well as the sensitivity of I KAS to [Ca(2+)]i. Our data indicated that the expression of SK1 and SK3 increased in HF.
Bisoprolol effectively attenuated the change and downregulated I KAS density as well as the sensitivity of I KAS to [Ca(2+)]i.