[Effect of mesenteric lymph duct ligation on lung injury in hemorrhagic shock rats]

To observe the effect of ligation of mesenteric lymph duct on release of oxygen free radical and inflammatory mediator in lung of rat with serious hemorrhagic shock at different periods, and explore the role of intestinal lymphatic pathway on acute lung injury (ALI).

Seventy-eight male Wistar rats were randomly divided into the sham operation group, shock group, and ligation group. The model of serious hemorrhagic shock was reproduced in shock group, ligation group, and mesenteric lymph flow was occluded by ligating mesenteric lymph duct in ligation group after resuscitation. Eight rats were sacrificed and the lung was harvested and homogenized for the determination of malondialdehyde (MDA), superoxide dismutase (SOD), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and myeloperoxidase (MPO) activity at 90 minutes after shock, 0, 1, 3, 6, 12 and 24 hours after transfusion and resuscitation.

The contents of MDA, TNF-alpha, IL-6 and MPO activity in lung homogenate of shock group were elevated after transfusion and resuscitation, and the levels were higher significantly at 3-12 hours, than those of the sham operation group, while the activity of SOD was significantly lower than that of sham operation group (P<0.05 or P<0.01). The contents of MDA, TNF-alpha, IL-6 and MPO in lung homogenate of ligation group at 3, 6, 12 and 24 hours after resuscitation were significantly lower than those of shock group at the same time points, and the SOD activity were higher (P<0.05 or P<0.01).

The results demonstrate that the ligation of mesenteric lymph duct could ameliorate ALI in rats with serious hemorrhagic shock, and its mechanism might relate with reduction of sequestration of neutrophils, thus reduce the release of TNF-alpha and IL-6, and also reduce the release of oxygen free radical and consumption of SOD. Therefore mesenteric lymphatics might play an important role in pathogenesis of ALI.