Effects of hyperthermia on avian red blood cells.

Our primary goal was to develop a model for studying the effects of heat on terminally differentiated cells. Using nucleated chicken red blood cells (RBC) as the model, heat dose-response and thermotolerance were investigated. A new haemolytic assay was developed to score them. Heating chicken RBC for as long as 3 h at 51.5 degrees C resulted in only small amounts of haemolysis immediately after heating. When haemolysis was scored 1-2 days after heating, heat-induced haemolysis increased with heating temperature and duration. Heat shock of 30-90 min at 42.6 degrees C just before heat challenge of 40 min at 51.5 degrees C, or heat shock of 15 min at 43.1 degrees C with incubation of 0-2 h at 35-37 degrees C prior to the same heat challenge induced thermotolerance, but the levels of heat resistance achieved were different. Similar experiments were performed using potassium leakage as the endpoint. Potassium leakage was measurable immediately after heating, and it increased with heating duration, but there was no correlation between potassium leakage and haemolysis. Potassium leakage was not a suitable criterion for measuring thermotolerance.