Whole body hyperthermia of rats decreases insulin binding to erythrocytes

125I-insulin binding to rat erythrocytes was studied to investigate the effect of whole body hyperthermia on the insulin receptor. Heat treatment of rats at 42 degrees C for 15 min caused a significant decrease (48.7% of control) in 125I-insulin binding to rat erythrocytes. Scatchard analysis showed that the decreased binding resulted from a decrease in the number of the insulin receptors rather than from a decrease in receptor affinity. The decreased receptor number for insulin showed no evidence of recovery, 2 h and 8 h after the hyperthermia. Plasma insulin levels remained lower than the control, up to 8 h after the hyperthermia, whereas plasma glucose, which decreased immediately after the hyperthermia, increased higher than the control, 8 h after the hyperthermia. The low plasma insulin level and decreased number of insulin receptor are believed to be possible factors for the elevation of plasma glucose.