Figure 8.
Changes in kinetic parameters of mechano-gating by suction are consistently antagonized by GsMTx4. A–C, histograms of SAKcaC open (left) or closed (right) times for control (A), suction (B, −40 mm Hg), and 50 nm GsMTx4 (with continuous suction of −40 mm Hg) are presented. The membrane potentials were held at −20 mV (upper panel), −50 mV (middle panel), and −80 mV (lower panel), respectively. Dashed lines at right in each panel represent the distributions of the closed-time components (τC1 and τC2) determined by the likelihood ratio test (see “Experimental procedures”). D, statistical comparison of the open-time constants (τO) among control, suction, and GsMTx4 with continuous suction at the voltages as indicated. E and F, statistical comparison of the closed-time constants τC1 (E) and τC2 (F) for control, suction, and GsMTx4 with continuous suction on the cell membrane. G, summarized relative weight area (AC1(%)) showing the percentage of the first closed component τC1. AC1 (%) = (AC1/(AC1 + AC2)) × 100%. The histograms in C were obtained from the single channel traces 25 min later following the back-filling when GsMTx4 was completely diffused to the patch membrane. Data points in D–G at each membrane potential represent at least three determinations. *, p < 0.05; **, p < 0.01. SAKcaCs were recorded from isolated chick ventricular myocytes.