Background: Water immersion stress (WIS) in rats causes decrease in deformability of red blood cells (RBC). We hypothesize that this phenomenon is mediated by reactive oxygen species. Since tirilazad mesylate (U74006F) is a potent scavenger of free oxygen radicals, the aim of this study was to investigate possible influence of this drug on WIS induced decrease in RBC deformability in rats.
Material/Methods: The rats were injected i. p. with tirilazad mesylate in a dose of 10 mg per kg body weight or vehiculum at the beginning of the experiment and immersed in water at 23°C to the depth of xyphoid for 5h. Control rats were kept in normal environment. After 6 h blood samples were collected for examination. An elongation index of RBC measured by Rheodyn SSD (Myrenne GmbH, Germany) was used as a parameter of deformability. Lipid peroxidation products have been assayed in RBC by BIOXYTECH® LPO-586™) kit.
Results: Tirilazad mesylate prevents a decrease in RBC deformability, but does not prevent an increase in concentration of lipid peroxidation products in erythrocytes during WIS.
Conclusions: Positive effect of tirilazad on stress induced decrease in RBC deformability is not related to inhibition of lipid peroxidation within the erythrocytes.

Keywords: Erythrocyte Deformability