Figure 9.

Process by which electronic cigarette vape (ECV) exposure triggers endothelial reactive oxygen species (ROS) generation and vascular endothelial dysfunction. ECV exposure generates ROS that increase the activation and expression of NADPH oxidase and trigger nitric oxide (NO) synthase (eNOS) uncoupling, leading to a vicious cycle of superoxide production and peroxynitrite formation, with protein modifications, and tetrahydrobiopterin (BH₄) depletion. Together these cause decreased NO synthesis and bioavailability, leading to endothelial dysfunction.