Effects of hyperthermia on cell survival and patterns of protein synthesis in endothelial cells from different origins.

Thermotolerance, transient resistance to heat induced by heat itself, is generally thought to be linked to the accumulation of 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 passage cultures of bovine aortic endothelial cells readily acquired thermotolerance; 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 brain capillary cells lost their ability to acquire heat resistance. Endothelial cells from different origins (aortic endothelium versus capillary endothelium) but from the same species and about the same passage number had a notably different response in terms of thermotolerance and 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. Furthermore, the data show that endothelial cells from different origins are dissimilar in their response to hyperthermia.