Disturbed Shear Stress Affects Disposition And Expression Of Caveolin-1, NO Synthase In Endothelial Cells

Many studies have demonstrated that atherosclerotic lesions develop primarily at sites of disturbed or altered blood flow, such as at bifurcations of blood vessel. The caveolin-1 serves as the structural components of caveolae, while also functioning as scaffolding proteins, capable of recruiting numerous signaling molecules to caveolae, as well as regulating their activities. Though previous studies have suggested that caveolae and endothelial caveolin-1 may regulate the vascular response to altered shear stress, it is not enough to explain the importance of caveolin-1 in inducing atherosclerotic lesions especially under disturbed shear stress. In order to study distribution and expression of caveolin-1 under disturbed shear stress, we established a novel PDMS-based vertical-step flow chamber to simulate the blood flow features of the AS predilection site in vitro. The catalytic sites of eNOS mainly located at the membrane of the caveolae and have the conjunctive sequence for Cav-1, NO which is the product of eNOS is the key regulation factor of blood vessel internal environment . Therefore, we detected the dilivery of NO, then investigated the interrelation between Cav-1, perturbed shear stress and NO.Cells were inoculated to the flow channel, and then exposed to disturbed shear stress (about 40 dynes/cm2). Cells under shear stress were allowed to grow for 6 hours, 12 hours, 24 hours and 48 hours,while culture media was collected for investigating NO, then these cells were processed directly for immunofluorescence staining with SABC-FITC and compared with cells under resting state. At the same time,the expression of Caveolin-1 gene was examined by RT-PCR.In our research, we got different results with cells cultured under laminar flow shear stress. Cells displayed ellipse under disturbed shear stress, and Caveolin-1 did not move toward the upstream edge of the cell, but moved toward the edge of the cell, and expression of Caveolin-1 gene in EC showed a significant decrease about 40% after exposure to shear stress for 48 hours. The release of NO was gradually decreased when cells were allowed to grow 6 hours, 12 hours, 24 hours, 48 hours. When cells were allowed to grow for 48 hours, the release of NO showed a significant decrease about 30%.The results showed that disturbed shear stress resulted in the disposition and expression of caveolin-1. This interaction might play an important role in transducing mechanical stimuli into intracellular signals. It might be a reason that caused ECs pathological changes.The synthesis of NO decreased with the loading time . It could result in that NO couldn't effectively inhibit leucocyte adheresion with ECs, platelets adhersion and vascular smooth muscle cell proliferation, thus Atheromatosis would be caused .This study might offer researchers a new reference to explain how atherosclerotic lesions develop primarily at sites of disturbed or altered blood flow.