This project tested the hypothesis that human erythrocytes pretreated with
Trolox (a water-soluble analog of
vitamin E) would be more susceptible to ultrasound (US)-induced
hemolysis by a cavitational mechanism because of an increased fragility of the erythrocyte membrane over that without
Trolox supplementation. Samples of whole human blood from apparently healthy donors (hematocrit approximately 40%) in vitro were supplemented or not supplemented with
Trolox at various concentrations, ranging from 1.8 to 0.0018 mg/mL plasma. Mechanical fragility tests indicated the
Trolox-treated blood in vitro exhibited greater
hemolysis than untreated blood in vitro (p < 0.001). US exposures at comparable acoustic amplitude, pulse length and duty factor in the presence of the US
contrast agent Albunex yielded differing results; at 1 MHz, the
Trolox-supplemented blood had significantly greater
hemolysis in vitro than non-
Trolox-supplemented blood; at 3 MHz, there was a substantial reduction in
hemolysis relative to that obtained at 1 MHz, and no statistically significant difference between the
Trolox-supplemented and -unsupplemented blood. There was also essentially no support for an alternative hypothesis that the
Trolox was functioning primarily as a
pro-oxidant. These collective experimental results support the hypothesis and suggest duality in the functionality of membranous
antioxidant inclusions or associations; they may foster protection against oxidative damage, yet render the cell less capable of withstanding mechanical stress.