Mannitol attenuates acute lung injury induced by infrarenal aortic occlusion-reperfusion in rats

Mannitol is used as a treatment for ischemia/reperfusion (IR) injury of various organs in humans, despite the fact that its effectiveness in vivo is still disputed. The purpose of this study was to determine the effects of mannitol on acute lung injury (ALI) induced by infrarenal aortic occlusion.

Male Wistar-albino rats were allocated into five groups: (i) sham-operated group, which received a laparotomy without IR injury (n = 12); (ii) IR group, which received 3 h of ischemia followed by 2 h of reperfusion (n = 12); (iii) IR + inferior caval phlebotomy (ICP) group, which was identical to group 2 except for 1 ml of blood aspiration from the inferior caval vein (n = 12); (iv) IR + mannitol-treated group, for which rats were subjected to IR and received a bolus injection of mannitol (n = 12); and (v) IR + ICP + mannitol-treated group, which underwent the same procedures as described for the previous groups. Arterial blood gas parameters were studied and bronchoalveolar lavage (BAL) was performed. Evans blue dye was injected into half of the rats. We biochemically assessed the degree of pulmonary tissue injury by investigating oxidative stress markers and enzymatic and nonenzymatic antioxidant markers, and evaluated ALI by establishing pulmonary leukosequestration and ALI scoring, histopathologically. Pulmonary edema was estimated by using Evans blue dye extravasation and wet/dry weight ratios.

Hypertonic mannitol treatment significantly reduced oxidative stress markers, and significantly increased enzymatic and nonenzymatic antioxidant markers in the lung tissues (P < 0.05). Arterial blood gas parameters were significantly ameliorated (P < 0.05), the BAL cytology was significantly better (P < 0.05), pulmonary leukosequestration and ALI scores were significantly decreased (P < 0.05), and pulmonary edema was significantly alleviated (P < 0.05) by mannitol administration.

This study clearly showed that mannitol treatment significantly attenuated the aortic IR-induced ALI. Further clinical studies are required to clarify whether mannitol has a useful role in ALI during surgeries in which IR-induced organ injury occurs.