Figure 5.

Mechano-sensitive single-channel currents from isolated nuclei. (A) A typical record of single-channel currents from a nucleus-attached patch in response to pipette suction (40 mm Hg) at an applied potential of +40 mV. Pipette and bath solutions were 145 mM KCl, 0.1 mM CaCl₂, 2 mM MgCl₂, 1.1 mM EGTA, 10 mM Hepes-K, at pH 7.4. (B) Single-channel records at different applied membrane potentials from −30 to +30 mV during constant pipette suction. (C) Current–voltage (I–V) curves from nucleus-attached patches recorded in symmetrical 145 mM KCl (○) or 72.5 mM CaCl₂ pipette/145 mM KCl (●) bath solutions. Each point represents the mean single-channel amplitude of the main open state (obtained from all-points total amplitude histograms) versus the relative membrane potential averaged over three separate experiments (± SD). (D) Relationship of channel activity to pipette suction strength at a relative membrane potential of +40 mV. Negative pressures applied to the pipette progressively increased channel activity. (E) Pressure dependence of channel open probability (NPo, where N is the number of channels in the patch and Po is the open probability of a single channel).