Figure 1 .

Effect of pH on large conductance K⁺ channels in isolated surface cells from rat distal colon. Typical recordings from an inside-out patch of membrane from a distal colonic surface cell isolated from K⁺ loaded animals at different V_com values, referenced to the pipette interior (K₂SO₄ solution containing 32 nM Ca²⁺ in bath, K₂SO₄ solution containing 1.2 mM Ca²⁺ in the pipette). (A) and (B) Recordings at bath pH values of 7.40 and 7.60 respectively. The dashed lines indicate zero current levels, upward current deflections indicate K⁺ flow from the bath to the pipette, and downward current deflections indicate K⁺ flow from the pipette to the bath.