Responses of WT MscS to crowding agent Ficoll 400. (A) The trace was recorded at 20-mV pipette voltage with stimulation by a 30-s step of constant pressure with five evenly interspersed saturating test pulses of 0.1 s in length (comb protocol). The peaks of current responses to test pulses in the control (0% Ficoll 400) reflect the kinetics of inactivation. In the presence of 10% Ficoll, the MscS population opens in response to the first pulse and then completely inactivates. (B) The kinetics of recovery after inactivation. The inset shows the pressure protocol consisting of a prolonged step of pressure followed by a series of test pulses. The kinetics of recovery is not influenced by 10% Ficoll.