Figure 5. Ca²⁺ permeation and blockade of MS channels.

Mechanogated currents (on the left) and corresponding I-V relationships (on the right) measured in cell-attached experiments with various Ca²⁺ concentrations (mm) in the pipette; NMDG was added to maintain the ionic strength; c indicates the closed state. A, in the presence of 2 mm CaCl₂, single-channel activity in the inward (at −100 mV) and outward (at +30 mV) direction was recorded. The I-V curve shows unitary conductance of 8 pS and a reversal potential of −39 mV. B, in the presence of 20 mm CaCl₂, no inward currents were observed, whereas outward channel activity was recorded. C, at 90 mm CaCl₂, MS currents were inhibited over the entire voltage range studied.