[Fibronectin or RGD peptide promotes nitric oxide synthesis of rabbit bronchial epithelial cells]

To find out whether the extracellular matrix component fibronectin plays a regulatory and protective role in bronchial epithelial cells, the present study was undertaken to detect the NO released from primary cultured rabbit bronchial epithelial cells (BEC) and the activity of NO synthesase (NOS) in cells. Stress with ozone was taken as the positive control, and the effects of fibronectin (Fn) or its specific sequence Arg-Gly-Asp (RGD peptide) was observed. The results showed: (1) Ozone stress enhanced NO release from BEC, and treatment with Fn also promoted the NO production. The effect of Fn could be blocked by calmodulin inhibitor W(7). (2) Both Fn and RGD showed a dose-dependent promotion on NO release. (3) The NOS activity was significantly elevated in Fn treated group and the effect of Fn was abolished by W(7). A dose-response relation in NOS activity was observed in either Fn treated or RGD treated group. It is concluded that the binding of fibronectin or its specific sequence RGD peptide with integrins of BEC plays a role in upregulating the NOS activity and the NO release, and calmodulin may take part in the pathway of signal transduction.