Extracorporeal circulation activates endothelial nitric oxide synthase in erythrocytes.

Background Extracorporeal circulation used in cardiopulmonary bypass and hemodialysis is often associated with severe hypotension, which is an important predictor for mortality and morbidity. One pathophysiological hypothesis includes nitric oxide (NO) generation. Recently, a functional NO synthase (endothelial type NO synthase [eNOS]), was found to be expressed in human red blood cells. However, to date, activation of red blood cell eNOS has not been shown. We hypothesized that eNOS in circulating red blood cells might be activated during extracorporeal circulation and thus contribute to hypotension through vasodilation upon NO release. Methods We collected blood samples from 28 patients e…