Figure 10. Inhibitory action of ryanodine on caffeine and InsP₃ responses.

After the first caffeine response was obtained, the tracheal SM strips were incubated in the relaxing solution G1 containing either dimethyl sulphoxide (DMSO; A) or ryanodine (B) for 30 min at 24 °C. The second caffeine response was evoked in the absence (A) or presence (B) of ryanodine. A similar protocol was carried out for the InsP₃ response in the absence (C) or presence (D) of ryanodine. Note that GTP was present 3 min before and during the InsP₃ response as indicated. The traces represent at least four separate experiments.