Cyclic stretch, reactive oxygen species, and vascular remodeling.

Blood vessels respond to changes in mechanical load from circulating blood in the form of shear stress and mechanical strain as the result of heart propulsions by changes in intracellular signaling leading to changes in vascular tone, production of vasoactive molecules, and changes in vascular permeability, gene regulation, and vascular remodeling. In addition to hemodynamic forces, microvasculature in the lung is also exposed to stretch resulting from respiratory cycles during autonomous breathing or mechanical ventilation. Among various cell signaling pathways induced by mechanical forces and reported to date, a role of reactive oxygen species (ROS) produced by vascular cells receives increasing attention. ROS play an essential role in signal transduction and physiologic regulation of vascular function. However, in the settings of chronic hypertension, inflammation, or acute injury, ROS may trigger signaling events that further exacerbate smooth muscle hypercontractility and vascular remodeling associated with hypertension and endothelial barrier dysfunction associated with acute lung injury and pulmonary edema. These conditions are also characterized by altered patterns of mechanical stimulation experienced by vasculature. This review will discuss signaling pathways regulated by ROS and mechanical stretch in the pulmonary and systemic vasculature and will summarize functional interactions between cyclic stretch- and ROS-induced signaling in mechanochemical regulation of vascular structure and function.