Figure 8.

Relative contribution of Ca²⁺ signaling and Ca²⁺ sensitivity to airway relaxation induced by formoterol isomers and (R)-albuterol. (A) The mean concentration-dependent relaxation of airways (contracted by MCh, 400 nM) induced by (R,R)-formoterol and (R)-albuterol (1–2,000 nM) in normal (black line, data from Figures 1D and 3B) and Ca²⁺-permeabilized lung slices (gray line, data from Figure 7C). Relaxation induced by (R,R)-formoterol and (R)-albuterol in normal and Ca²⁺-permeabilized lung slices was significantly different (*P < 0.05). (B) The mean concentration-dependent relaxation of airways (contracted by MCh, 400 nM) induced by low concentrations of (R,R)-formoterol (0.5–10 nM) in normal (black line, data from Figure 3D) and Ca²⁺-permeabilized lung slices (gray line; *P < 0.05; n = 5 mice). Mean (±SD) values are presented; a minimum of three experiments was performed for each concentration for each mouse. (C) The mean concentration-dependent relaxation of airways (contracted by MCh, 400 nM) induced by racemic- and (S,S)-formoterol in normal (black line, data from Figure 1D) and Ca²⁺-permeabilized slices (gray line, data from Figure 7C).