Role of Rac1 in augmented endothelin-1-induced bronchial contraction in airway hyperresponsive mice.

It has recently been exhibited that Rac1 expression is increased in the bronchial tissue of a murine model with repeated antigen-challenged airway hyperresponsiveness (AHR). In the present study, the role of Rac1 in endothelin-1 (ET-1)-induced bronchial contraction and myosin light chain (MLC) phosphorylation was examined in AHR mice. Enhanced reactions in AHR mice were prevented by the Rac1 inhibitor NSC23766. These findings suggest that increased activation of Rac1 might be responsible for the enhancement of the bronchial contraction induced by ET-1 in AHR.