HYPERTONICITY INDUCES INJURY TO CULTURED HUMAN ENDOTHELIUM - ATTENUATION BY GLUTAMINE

Background. Although most preservation solutions as well as some cardi oplegic solutions used for organ storage and transplantation are hyper tonic, the effects of extracellular hypertonicity on endothelium are n ot well established. Aims of this study were to evaluate the response of cultured human saphenous vein endothelial cells to extracellular hy pertonicity and to investigate the role of the amino acid glutamine in preventing endothelial damage in vitro. Methods. Eight distinct strai ns of human saphenous vein endothelial cells were studied. Hypertonic (350 and 400 mosm/kg) media were obtained by supplementing culture med ium with sucrose. Cell viability was assessed in the absence or the pr esence of glutamine through the determination of cell number and prote in content of the cultures. Confocal microscopy of cells loaded with t he fluorescent dye calcein was also performed. Results. Exposure of hu man saphenous vein endothelial cells to hypertonic media without gluta mine caused significant cell loss within 30 minutes. Cell loss progres sed steadily during incubation and after 6 hours reached 50% at 350 mo sm/kg and 65% at 400 mosm/kg. In the presence of 2 mmol/L glutamine, e ndothelial damage was completely prevented at 350 mosm/kg and signific antly lessened at 400 mosm/kg compared with glutamine-free media. Conf ocal microscopy showed that most hypertonicity-treated cells exhibited the typical features of an apoptotic death and confirmed the osmoprot ective effect of glutamine. Conclusions. These results indicate that t he supplementation of hypertonic storage solutions with glutamine migh t exert a partial osmoprotective effect and suggest that the relations hip between endothelial damage and tonicity of storage and cardioplegi c solutions should be carefully investigated. (C) 1997 by The Society of Thoracic Surgeons.