Mesenteric lymph duct ligation provides long term protection against hemorrhagic shock-induced lung injury

Recently we have shown that ligation of the main mesenteric lymph (MLN) duc t prior to an episode of hemorrhagic shock (HS) prevents shock-induced lung injury. Yet, ligation or diversion of intestinal lymph immediately prior t o injury is not clinically feasible. Diversion of intestinally derived lymp h after injury to protect against secondary insults is possible, but it is not known how long the protective effects of lymph ligation would last. Thu s, we tested whether ligation of the MLN duct seven days prior to HS would still be protective. Male Sprague-Dawley rats were subjected to laparotomy with or without MLN duct ligation. Seven days later, half of the sham and a ctual MLN duct ligated animals randomly were selected to undergo HS (30 mmH G for 90 min). The other half of the animals was subjected to sham shock. L ung permeability, pulmonary myeloperoxidaae (MPO) activity, and bronchoalve olar fluid (BALF) protein content were used to determine lung injury. Lymph atic division 7 days prior to HS continued to prevent shack induced lung in jury as assessed by a lower Evans Blue dye concentration, BALF protein and MPO activity. in addition, there was no evidence of Patent Blue dye in the previously ligated MLN duel. Since ligation of the main mesenteric lymphati c duct continues to protect against shock-induced lung injury 1 week after duct ligation, it is feasible that lymphatic ligation performed after an in jury remains protective against certain secondary insults for at least 1 we ek.