Figure 4.

Effect of shear stress pattern on CYP1A1 and CYP1B1 mRNA and protein expression. Human umbilical vein endothelial cells (HUVECs) (n = 5–9) or human aortic endothelial cells (HAECs) (n = 4) were subjected to one of three different flow regimes: low shear stress (1 dyne/cm²), steady arterial shear stress (15 dynes/cm²), or carotid sinus reversing shear stress for 24 h. CYP1A1 and CYP1B1 mRNA and protein expression in HUVECs (A–C) were highest under 15 dynes/cm² and greatly reduced under reversing shear stress. CYP1A1 and CYP1B1 had similar trends of expression in HAECs (D–F). Significance was assessed using analysis of variance, followed by Tukey's post hoc test; *P < 0.05 vs. static conditions and ^‡P < 0.05 between indicated conditions.