Mechanosensing by K_ATP channels and PECAM‐1 contributes to superoxide generation in mouse model of lung ischemia

Abstract

Vascular responses to shear stress arising from blood flow entail the involvement of mechanosensors on endothelial cells. We showed earlier that the KATP channel is an important component of the flow sensing machinery in the pulmonary endothelium. Based on previous studies (E. Tzima, Nature, 2005), we posited that the platelet endothelial cell adhesion molecule 1 (PECAM‐1), by virtue of its junctional location and cytoskeletal linkage, could serve as a mechanosensor that senses loss of blood flow. Using an isolated perfused mouse lung and confocal imaging of ROS probes in the pulmonary microvasculature, we detected ROS generation upon loss of shear (ischemia) in wild type lungs that was significantly attenuated both in KATP and PECAM‐1 knockout (KO) mouse lung. By image analysis, KATP KO and PECAM‐1 KO were capable of generating only 62% and 51% of the ROS level detected in wild type (WT), respectively. High‐performance liquid chromatography (HPLC) of dihydroethidium extracted from the ischemic lung was used to detect superoxide (SO). In agreement with the imaging data, HPLC analysis showed a partial attenuation of SO in the PECAM‐1 KO, indicating SO as the parent oxidant species and reinforcing the confocal imaging method. These results indicate that KATP channel and PECAM‐1 may be a part of a mechanosensing machinery that contributes to the generation of SO in a shear‐dependent manner. NHLBI‐T32‐S54932