Damage to erythrocytes from long-term heat stress
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1Department of Biomedical Engineering and Applied Therapeutics, Cleveland Clinic Foundation, Ohio 44195.
1. Erythrocytes are known to haemolyse in vitro at 48-50 degrees C. We hypothesized that erythrocytes might be damaged at much lower temperatures if they are incubated for prolonged periods. Erythrocytes from healthy human donors (n = 7) were incubated at 37, 40, 42, 44, 46 or 48 degrees C for 4-48 h. The haemolytic percentage and osmotic fragility were then measured by a modification of the method of Parpart et al. 2. Significant haemolysis and increased fragility were not observed at any temperatures after incubation for 4 h. However, the haemolytic percentage increased after incubation for 24 h at 44 degrees C (9.1 +/- 4.9%, P less than 0.01), 46 degrees C (52.4 +/- 14.1%, P less than 0.01) and 48 degrees C (98.0 +/- 2.6%, P less than 0.01) and after incubation for 48 h at 42 degrees C (9.8 +/- 4.5%, P less than 0.01) when compared with the values before heating (1.1 +/- 0.9%). The osmotic fragility also increased after incubation for 24 h at and above 42 degrees C. 3. Although heat-induced haemolysis and an increase in fragility have not been known to occur below 48 degrees C, these were quite apparent after incubation for 24-48 h at only 42 degrees C. This suggests that with regard to thermal effects, it is important to consider not only the temperature but also the duration of heating.
1. Erythrocytes are known to haemolyse in vitro at 48-50 degrees C. We hypothesized that erythrocytes might be damaged at much lower temperatures if they are incubated for prolonged periods. Erythrocytes from healthy human donors (n = 7) were incubated at 37, 40, 42, 44, 46 or 48 degrees C for 4-48 h. The haemolytic percentage and osmotic fragility were then measured by a modification of the method of Parpart et al. 2. Significant haemolysis and increased fragility were not observed at any temperatures after incubation for 4 h. However, the haemolytic percentage increased after incubation for 24 h at 44 degrees C (9.1 +/- 4.9%, P less than 0.01), 46 degrees C (52.4 +/- 14.1%, P less than 0.01) and 48 degrees C (98.0 +/- 2.6%, P less than 0.01) and after incubation for 48 h at 42 degrees C (9.8 +/- 4.5%, P less than 0.01) when compared with the values before heating (1.1 +/- 0.9%). The osmotic fragility also increased after incubation for 24 h at and above 42 degrees C. 3. Although heat-induced haemolysis and an increase in fragility have not been known to occur below 48 degrees C, these were quite apparent after incubation for 24-48 h at only 42 degrees C. This suggests that with regard to thermal effects, it is important to consider not only the temperature but also the duration of heating.