Background: This study aimed to investigate alterations in hemorheology by cold exposure, in vivo and ex vivo, and to determine their relationship to oxidative stress.
Material/Methods: Rats were divided into 2 in vivo and ex vivo cold exposure groups. The in vivo group was further divided into control (AR), AC (4°C, 2 hours) and ALTC (4°C, 6 hours) subgroups; and the ex vivo group was divided into control (BR) and BC (4°C, 2 hours) subgroups. Blood samples were used for the determination of erythrocyte deformability, aggregation, and oxidative stress parameters.
Results: Erythrocyte deformability and aggregation were not affected by 2-hour ex vivo cold exposure. While 2 hour in vivo cold exposure reduced erythrocyte deformability, it returned to normal after 6 hours, possibly due the compensation by acute neuroendocrine response. Six hours of cold exposure decreased aggregation index, and might be an adaptive mechanism allowing the continuation of circulation. Aggregation of ex vivo groups was lower compared to in vivo groups. Cold exposure at various temperatures did not cause alterations in plasma total oxidant antioxidant status and oxidative stress index (TOS, TAS, OSI) when considered together.
Conclusions: Results of this study indicate that the alterations observed in hemorheological parameters due to cold exposure are far from being explained by the oxidative stress parameters determined herein.

Keywords: Oxidants - blood, Hemorheology, Erythrocyte Deformability, Erythrocyte Aggregation, Cold Temperature, Antioxidants - metabolism, Random Allocation