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

This research project tested the hypothesis that cold-equilibrated (similar to 0 degrees C) human erythrocytes in vitro in the presence of an ultrasound contrast agent (Albunex((R))) will undergo greater ultrasound-induced hemolysis than physiologically equilibrated (37 degrees 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 mu s 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 degrees C blood plasmas, the cold (similar to 0 degrees C) erythrocytes displayed substantially greater amounts of ultrasound-induced hemolysis than the physiological (37 degrees C) erythrocytes. The data supported the hypothesis. (E-mail: Morton-Miller@urmc.rochester.edu) (c) 2006 World Federation for Ultrasound in Medicine & Biology.