Effect of PKC inhibitor GF-109203X on Ca²⁺ sensitization induced by PMA or contractile agonists. Lung slices were first exposed to 20 mM caffeine plus 25 µM ryanodine (upper bars) to induce Ca²⁺ permeabilization. (A) Representative experiment showing the effect of airway exposure to 1 µM GF-109203X before and during stimulation with 10 µM PMA. Contractile response of the airways after Ca²⁺ permeabilization was accessed with 0.5 µM 5-HT before their exposure to GF-109203X and PMA. This experiment is representative of six lung slices from three mice. (B and C) Airway contraction induced by PMA or 0.1 U/ml thrombin and the subsequent relaxation induced by GF-109203X. (D) Summary of the effect of GF-109203X on airway contraction in Ca²⁺-permeabilized airways precontracted with 10 µM PMA, 0.25 µM ACh, 0.5 µM 5-HT, and 0.1 U/ml thrombin. Airway relaxation (mean ± SEM; n = 5 lung slices from 3 mice) was obtained from experiments similar to that shown in B and C using the appropriated contractile agonist or PMA.