Fig. 11.

The effect of tetracaine on MCh-induced contraction and the [Ca²⁺]_i of permeabilized airway SMCs. The airway SMCs were permeabilized to Ca²⁺ by treatment with 20 mM caffeine and 50 μM ryanodine and washed with HBSS supplemented with 20 mM HEPES buffer (sHBSS) for 10 min. A representative trace (A) and summary data (B) showing the effect of tetracaine on the airway contracted with 200 nM MCh are shown. Increasing concentrations of tetracaine relaxed the airway. The extent of relaxation is expressed as a percentage of contracted lumen area induced by MCh. Data represent the means ± SE from 4 different slices from 2 mice. A representative trace (C) and summary data (D) demonstrate that in permeabilized SMCs, the [Ca²⁺]_i remained at a high constant level throughout the experiments (the [Ca²⁺]_i was expressed as ratio of the levels before and after drug exposure in D). Data represent the means ± SE from 4 different slices from 2 mice.