Role of α2 adrenergic receptors in dexmedetomidine-induced inhibition of lipid peroxidation during lung ischemia-reperfusion injury in rats

Abstract

Objective To evaluate the role of α2 adrenergic receptors in dexmedetomidine-induced inhibition of lipid peroxidation during lung ischemia-reperfusion (I/R) injury in rats. Methods Thirty-two isolated rat lungs in which the model of isolated lung perfusion was successfully established, were divided into 4 groups (n=8 each) using a random number table: control group (C group), I/R group, dexmedetomidine group (D group) and dexmedetomidine plus yohimbine group (DY group). The isolated lungs were subjected to 60 min of ischemia and apnea followed by 75 min of reperfusion and ventilation to establish the model of isolated lung I/R injury.From the beginning of reperfusion, 2.3 ng/ml dexmedetomidine was added to the perfusion fluid in D group, and 2.3 ng/ml dexmedetomidine and 0.4 μg/ml yohimbine (an α2 adrenergic receptor blocker) were added to the perfusion fluid in DY group.Lung specimens were obtained immediately after the end of reperfusion for determination of the wet/dry weight ratio (W/D ratio), superoxide dismutase (SOD) activity (by using modified pyrogallol autoxidation method) and malondialdehyde (MDA) content (by thiobarbituric acid method) and for examination of the pathological changes (using haematoxylin and eosin staining). Results Compared with C group, the W/D ratio and MDA content were significantly increased, and the SOD activity was decreased in I/R, D and DY groups (P<0.05). Compared with I/R group, the W/D ratio and MDA content were significantly decreased, and the SOD activity was increased in D group (P<0.05). Compared with DY group, the W/D ratio and MDA content were significantly decreased, and the SOD activity was increased in group D (P<0.05). The pathological changes of lung tissues were significantly attenuated in D group as compared with I/R and DY groups. Conclusion The mechanism by which dexmedetomidine inhibits lipid peroxidation is related to activating α2 adrenergic receptors during lung I/R injury in rats. Key words: Dexmedetomidine; Lung; Reperfusion injury; Receptors, adrenergic, alpha-2; Lipid peroxidation