Comparative hemolytic effectiveness of 1 MHz ultrasound on human and rabbit blood in vitro.

This project continued testing of the general working hypothesis that cell size is a physical determinant in extent of ultrasound (US)-induced hemolysis, the larger the cell the greater the lysis. For this project, the specific hypothesis tested was that human erythrocytes, being larger than rabbit erythrocytes, would be the more sensitive to sonolysis induced by inertial cavitation in the presence of Albunex, a US contrast agent. The rationale behind this hypothesis was 1. an earlier-published analytic construct indicating an inverse relation between particle size and the shear force required for deformation, and 2. a number of independent demonstrations that, among sized populations of erythrocytes, an inverse relation exists between erythrocyte volume and mechanically-induced shear forces in the cell-bathing medium; namely, the larger the cell, the less shear force required to rupture the cell's membrane. The present data support the hypothesis; over six independent trials, the mean corpuscular volumes of human (H) and rabbit (R) erythrocytes were 89.5 and 64.1 microm(3), respectively, H > R (p << 0.001), and the ratio of US-induced hemolysis in H to R blood in vitro was 1.12:1.0 (p < 0.004).