Figure 5.

Effect of ryanodine on airway contraction and Ca²⁺ oscillations. (A) Representative response of the effect of ryanodine (50 μM) on His-induced (500 nM) airway contraction (% of the initial area with respect to time). Ryanodine had no significant effect on airway contraction during 15-minute exposure (n = 4 slices from 3 individuals). (B) Representative response of the effect of ryanodine on His-induced Ca²⁺ oscillations of airway SMCs (as indicated by the change in fluorescence intensity with respect to time). Ryanodine did not inhibit the Ca²⁺ oscillations or alter the propagation of the associated Ca²⁺ waves (n = 5 slices from 2 individuals). (C) A representative response indicating that KCl-induced (50 mM) Ca²⁺ oscillations were inhibited within 3 minutes of ryanodine exposure. In addition, the Ca²⁺ baseline was elevated as the Ca²⁺ oscillations were inhibited (n = 2 slice from 2 individual). (D) A representative line scan analysis across several airway SMCs (indicated by the white line in the left image) showing the immediate induction of Ca²⁺ oscillations when the lung slice loaded with caged IP₃ was flashed with ultraviolet (UV) light to release IP₃ from its caged compound. (E) Line scan plot showing that IP₃ released by a UV light flash from caged IP₃ induces Ca²⁺ oscillations in the presence of 50 μM ryanodine (n = 3 slices from 2 individuals).