Effects of heat on fragility and morphology of human and calf erythrocytes.

It is important to know the species differences when data from animal experiments are interpreted for human application. This in vitro study focused on the effects of heat, a major concern in mechanically actuated artificial heart development, on the physiology of human and calf erythrocytes (RBC). RBC from calves and healthy human donors were incubated at 25, 37, 46, 48, 50, or 52 degrees C for 1 h. Osmotic fragility was tested and morphological changes were then observed by scanning electron microscopy. The osmotic fragility of human and calf RBC increased at and above 50 degrees C. After incubation at 50 degrees C, 6% of human and 1% of calf RBC hemolyzed. Changes in surface morphology, which included spherocytic or echinocytic forms, were observed in 97% of human and 19% of calf RBC after incubation at 50 degrees C. In conclusion, human RBC showed greater changes in osmotic fragility and morphology at and above 50 degrees C. These changes, however, were not observed in either species after 1 h incubation at 46 degrees C.