ABSTRACT
Objective To evaluate the effect of regional hypothermia on limb ischemia-reperfusion (I/R) injury in a rabbit model of hemorrhagic shock.Methods Eighteen healthy adult New Zealand white rabbits of both sexes,weighing 2.0-2.5 kg,were divided into 3 groups (n=6 each) using a random number table:sham operation group (S group),limb I/R group (I/R group) and regional hypothermia group (RH group).Rabbits were shot with 0.25 g steel ball with a 7.62 mm smoothbore at the middle and lower 1/3 of the left hindlimb in I/R and RH groups.When the blood pressure was stable for 30 min after injury,blood was drawn via the right femoral artery at a rate of 2 ml/min until mean arterial pressure decreased to 45-50 mmHg.Then a rubber tourniquet was used to ligate left hindlimbs 10 min later.The injured limb was cooled down for 4 h after applying tourniquet to maintain the subcutaneous temperature at 9-11 ℃ in group RH.After tourniquet was applied for 4 h,perfusion was restored and lasted 6 h.After catheterization (T0) and at 2,4 and 6 h of reperfusion (T1-3),blood samples were collected from the right femoral artery for blood gas analysis and for determination of tumor necrosis factor-α (TNF-α),interleukin-2 (IL-2) and IL-6 concentrations in serum (by enzyme-linked immunosorbent assay).The animals were sacrificed at T3,and tissues around the margin of the inferior lobe of right lung were obtained for examination of the pathological changes which were scored and for determination of wet to dry weight ratio (W/D ratio).Results Compared with group S,the respiratory rate was significantly increased and PaCO2 was decreased at T2,3,the pathological score and W/D ratio were increased,and the concentrations of TNF-α,IL-2 and IL-6 in serum were increased at T1-3 in I/R and RH groups (P＜0.05).Compared with group I/R,the respiratory rate was significantly decreased and PaCO2 was increased at T2,3,the pathological score and W/D ratio were decreased,and the concentrations of TNF-α,IL-2 and IL-6 in serum were decreased at T1-3 (P＜0.05),and the pathological score was significantly attenuated in group RH.Conclusion Regional hypothermia can reduce limb I/R injury in a rabbit model of hemorrhagic shock,and the mechanism may be related to inhibiting systemic inflammatory responses.