Sensitization of KCl-induced airway contraction by PKC activation and thrombin. (A and B) Representative experiments showing the increase in KCl-induced airway contraction caused by the exposure of lung slices to 10 µM PMA or 0.1 U/ml thrombin, respectively. (C) Summary of effects of sHBSS (control), PMA, and thrombin on airway contraction induced by 50 mM of isosmotic KCl. The ratios were calculated by dividing the KCl-induced airway contractions after and before the treatments from experiments similar to those shown in A and B. *, significantly higher than the first stimulation (P < 0.01).