Characterization of the Signaling Pathways Activated by KCl-Induced RTK Stimulation in Guinea Pig Airways.

We found that, in guinea pig airway smooth muscle, the pharmacological inhibition of RTKs significantly decreased the contraction induced by 20 mM KCl. We observed that MEK pharmacological inhibitors diminished the contraction induced by 20 mM KCl, but not that induced by 60 mM. On the other hand, ERK inhibitors also altered the contraction generated by 20 mM KCl. When a ROCK inhibitor was tested, we found that it significantly inhibited the KCl-induced contraction. These results were complemented with Western blot experiments, and a decrease in ERK phosphorylation was noticed when the RTKs were inhibited. When MEK and ERK inhibitors were used, we also observed a decrease in ERK phosphorylation. In the case of MYPT1, its phosphorylation decreased when RTK, MEK, and ROCK inhibitors were used. In conclusion, we found that, in guinea pig airway smooth muscle, the contraction induced by 20 mM KCl includes the activation of RTKs and, in turn, MEK-ERK and ROCK.