Vascular BK channels are composed of pore‐forming α‐ and accessory β1‐subunits.39, 40 It is well known that β1‐subunits regulate BK channel functions by increasing Ca2+ sensitivity and open dwell time of α‐subunits.41, 42 Through single‐channel recording, the present study found that the effectiveness of Ca2+ in activating BK channels at physiological Em was increased in CHF and HHF group, without significant difference between those two groups. The gene discussed is KCNMA1; the disease is congestive heart failure.