Endothelial cell response to different mechanical forces

Purpose: Endothelial cells (ECs) are subjected to the physical forces induc ed by blood flow. The aim of this study was to directly compare the EC sign aling pathway in response to cyclic strain and shear stress in cultured bov ine aortic ECs. Materials and Methods The ECs were seeded on flexible collagen I-coated sil icone membranes to examine the effect of cyclic strain. The membranes were deformed with a 150-mm Hg vacuum at a rate of 60 cycle/min for up to 120 mi nutes. For a comparison of the effect of shear stress, ECs from the same ba tch as used in the strain experiments were seeded on collagen I-coated sili cone sheets. The ECs were then subjected to 10 dyne/cm(2) shear with the us e of a parallel now chamber for up to 120 minutes. Activation of the mitoge n-activated protein kinases was assessed by determining phosphorylation of extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase (JNK), and p38 with immunoblotting. Results: ERR, JNK and p38 were activated by both cyclic strain and shear st ress. Both cyclic strain and shear stress activated JNK. with a similar tem poral pattern and magnitude and a peak at 30 minutes. However, shear stress induced a more robust and rapid activation of ERK and p38, compared with c yclic strain. Conclusions: Our results indicate that different mechanical forces induced differential activation of mitogen-activated protein kinases. This suggests that there may be different mechanoreceptors in ECs to detect the differen t forces or alternative coupling pathways from a single receptor.