Mechanosensing with restart of flow drives K _ATP channel induced NOX2 activation in a model of Lung Ischemia Reperfusion

From our earlier studies in lung ischemia, we concluded that endothelial mechanotransduction with stop of flow in the lung activates the generation of reactive oxygen species (ROS) as a result of K ATP closure that leads to NOX2 activation. As the next phase, we evaluated the role of mechanosignaling with reperfusion (I/R). We now propose that the increase in shear with reperfusion triggers a mechanosignaling cascade similar to that associated with ischemia. Isolated perfused mouse lungs and pulmonary endothelial cells showed a 2 fold increase in ROS production (as monitored by ROS sensitive dyes H 2 DCFDA, H 2 DFFDA and DHE) with ischemia that is further enhanced by 3–3.5 fold upon reperfusion. This was not observed in lungs from K ATP channel null and NOX2 mice. Lungs subjected to ischemia or I/R show ~1.8 fold increase in lung damage (as assessed by 8‐isoprostanes, TBARS, permeability) with ischemia and a ~2.5 fold increase during the reperfusion period. Understanding the initiation of reperfusion signaling has potential application in lung transplantation which requires reperfusion of a previously ischemic lung; thus this model is relevant to design strategies that can reduce NOX2 activation and resultant injury.