Biological and environmental factors affecting ultrasound-induced hemolysis in vitro: 5. Temperature

This research project tested the hypothesis that cold-equilibrated (∼0°C) human erythrocytes in vitro in the presence of an ultrasound contrast agent (Albunex®) will undergo greater ultrasound-induced hemolysis than physiologically equilibrated (37°C) human erythrocytes in vitro because of a temperature-related transition in membrane fluidity leading to increased fragility. First, it was shown that cold-equilibrated erythrocytes are more susceptible to mechanically induced hemolysis than physiologically equilibrated erythrocytes. Second, when adjustments were made for (1) temperature-dependent efficiencies of a 1-MHz transducer (200 μs pulse length, 20 ms interpulse interval, 30 s exposure duration) such that when cold or physiological temperatures were employed, there were equivalent acoustic outputs in terms of peak negative pressure (MPa P−) and (2) comparable viscosities of the 0 and 37°C blood plasmas, the cold (∼0°C) erythrocytes displayed substantially greater amounts of ultrasound-induced hemolysis than the physiological (37°C) erythrocytes. The data supported the hypothesis. (E-mail: [email protected])