Activation of endothelial NADPH oxidase during normoxic lung ischemia is K ATP channel dependent

• Published in: American journal of physiology. Lung cellular and molecular physiology 2005-12, Vol.289 (6), p.L954-L961
• Main Authors: Zhang, Qunwei, Matsuzaki, Ikuo, Chatterjee, Shampa, Fisher, Aron B.
• Format: Article
• Language: English
• ISSN: 1040-0605; 1522-1504
• DOI: 10.1152/ajplung.00210.2005

Previous studies have shown endothelial cell membrane depolarization and generation of reactive oxygen species (ROS) in endothelial cells with abrupt reduction in shear stress (ischemia). This study evaluated the role of ATP-sensitive potassium (K ATP ) channels and NADPH oxidase in the ischemic response by using Kir6.2−/− and gp91 phox −/− mice. To evaluate ROS generation, we subjected isolated perfused mouse lungs labeled with 2′,7′-dichlorodihydrofluorescein (DCF), hydroethidine (HE), or diphenyl-1-pyrenylphosphine (DPPP) to control perfusion followed by global ischemia. In wild-type C57BL/6J mice, imaging of subpleural endothelial cells showed a time-dependent increase in intensity for all three fluorescence probes with ischemia, which was blocked by preperfusion with cromakalim (a K ATP channel agonist) or diphenyleneiodonium (DPI, a flavoprotein inhibitor). Endothelial cell fluorescence with bis-oxonol, a membrane potential probe, increased during lung ischemia indicating cell membrane depolarization. The change in membrane potential with ischemia in lungs of gp91 phox −/− mice was similar to wild type, but ROS generation did not occur. Lungs from Kir6.2−/− showed marked attenuation of the change in both membrane potential and ROS production. Thus membrane depolarization during lung ischemia requires the presence of a K ATP channel and is required for activation of NADPH oxidase and endothelial ROS generation.