Endothelin-1-induced translocation of RhoA is mediated by endothelin ETA receptors in rat bronchial smooth muscle

To clarify the receptor subtype(s) contributing to the RhoA activation by endothelin-1 in bronchial smooth muscle, the effects of BQ-123 [cycro(D-Asp-Pro-D-Val-Leu-D-Trp)], an endothelin ETA receptor antagonist, and/or BQ-788 [2,6-dimethylpiperidinecarbonyl-g-methyl-Leu-Nin-(Methoxycarbonyl)-D-Trp-D-Nle], an endothelin ETB receptor antagonist, on the endothelin-1-induced translocation of RhoA to plasma membrane were examined. Incubation of rat bronchial smooth muscle with endothelin-1 induced a distinct translocation of RhoA to plasma membrane, indicating an activation of RhoA by endothelin-1. The endothelin-1-induced translocation of RhoA was completely blocked by treatment with BQ-123, whereas BQ-788 had no effect. Thus, endothelin ETA but not ETB receptors might be involved in the endothelin-1-induced translocation of RhoA in rat bronchial smooth muscle.