Moderate hypothermia suppressed excessive generation of superoxide anion radical and inflammatory reactions in blood and liver in heatstroke: Laboratory study in rats

Abstract

The study was performed to demonstrate superoxide radical (O2·–) generation, systemic inflammation and liver injury caused by heatstroke and to reveal suppressive effects of moderate hypothermia. Heatstroke was defined as achieving pharyngeal temperature of 40°C with arterial pressure reduction. Heatstroke rats were divided to four groups by the temperature after the onset; 40°C, 37°C, 32°C and sham-treated with 37°C. O2·– current was measured continuously in the right atrium using an electrochemical O2·– senor. The O2·– current increased in all groups except for the sham-treated group during the induction. After the onset of heatstroke, the O2·– current was suppressed with temperature-dependency. Plasma and liver high-mobility group box 1, intercellular adhesion molecule-1, plasma aspartate aminotransferase and alanine aminotransferase were also suppressed with the suppression of O2·– generation. Therefore, excessive O2·– generation might be a key factor in heatstroke and the suppression with moderate hypothermia would be a therapeutic modality.