Effects of Hyperthermia on Cell Survival and Patterns of Protein Synthesis in Endothelial Cells from Different Origins1

Thermotolerance, transient resistance to heat induced by heat itself, is generally thought to be linked to the accumulationof heat-shock proteins in eukaryotic cells. The induction of thermotolerance and the synthesis of heat-shock proteins in primary and passage cultures of bovine aortic endothelium, passage cultures of bovine brain capillaries, and passage cultures of rat epididymal capillaries were examined. Primary and pas sage cultures of bovine aortic endothelial cells readily acquired thermo tolerance; however, passage cultures of rat epididymal capillary cells and bovine brain capillary cells were very heat sensitive. In all endothelial cell types examined except rat epididymal capillary cells, the levels of HSP71, the most inducible of the HSP70 family, correlated well with thermotolerance. With prolonged passage, rat epididymal capillary cells and bovine braincapillary cells lost their ability to acquire heat resistance. Endothelial cells from different origins (aortic endothelium versuscapil lary endothelium) but from the same species and about the same passage numberhad a notably different response in terms of thermotoleranceand synthesis of proteins after exposure to hyperthermia. The results of this study suggest that, while the expression of HSP71 may be a good indicator of heat resistance, the reverse is not necessarily true. Further more, the data show that endothelial cells from different origins are dissimilar in their response to hyperthermia.