Resistance to multi organ damage after hemorrhagic shock induced ischemia/reperfusion in arctic ground squirrels

Abstract

During hemorrhagic shock (HS), the body undergoes global ischemia as blood pressure drops below the threshold at which tissues can be adequately perfused. Resistance to ischemia/reperfusion (I/R) injury is a characteristic of hibernating mammals. The present study sought to determine if arctic ground squirrels (AGS) are protected from HS induced I/R and if any protection is dependent upon their hibernation season. Rats, euthermic AGS, and interbout arousal AGS were subject to HS by withdrawing blood to a mean arterial blood pressure (MAP) of 35 mmHg. Low MAP was maintained for 20 min and then the animals were reperfused with Ringers. The animals’ temperature was maintained at 36.5–37.5 °C. After reperfusion, animals were monitored for 3 hrs then tissues and blood were collected for histopathology, clinical chemistries, and cytokine level analysis. In addition, a group rats and AGS were monitored for three days after HS to access survival and physiological impairment. AGS were able to survive three days beyond HS with no impairment noticeable after 12 hrs whereas rats did not survive to 12 hrs. Regardless of season, blood chemistries indicate no organ damage in the ground squirrel while the rat showed signs of liver damage. In addition, both winter and summer AGS had a lower cytokine response after HS than did rats. Funded by USAMRMC W81XWH009‐2‐0134.