title: The influence of hematocrit on hemolysis by ultrasonically activated gas-filled micropores.
abstract: In vitro studies of ultrasonic bioeffects typically employ cell number densities much lower than those present in vivo, which can lead to difficulties in interpretation and extrapolation. In this study, the influence of cell number density on the hemolytic effect of ultrasonic gas-body activation (a low-level form of cavitation) was investigated. Hydrophobic membranes with 4 micron diameter gas-trapping micropores were immersed in saline suspensions of erythrocytes with hematocrits (HCT) from 0.001 to 0.3, and whole blood, and exposed to 1.7 MHz continuous-wave ultrasound in a 37 degrees C saline-filled exposure bath. Significant hemolysis was observed for spatial peak intensities above about 45-90 mW/cm2 for the 16 min exposures. The percentage of cells hemolyzed tended to decrease with increasing hematocrit such that the number of cells hemolyzed, which is proportional to the product of the hematocrit and the percent hemolysis, remained roughly constant. Readily observable in vitro effects may therefore become quite subtle when diluted, as for in vivo conditions, by large numbers of cells.
authors.affiliation: Battelle Pacific Northwest Laboratory, Richland, WA 99352.
authors.forename: D L
authors.initials: DL
authors.lastname: Miller
mesh_terms: D001772:Blood Cell Count; D005740:Gases; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D006461:Hemolysis; D006801:Humans; D008567:Membranes, Artificial; D013053:Spectrophotometry; D014465:Ultrasonics
chemical_list: D005740:Gases; D006454:Hemoglobins; D008567:Membranes, Artificial