Mesenteric lymph from rats subjected to trauma-hemorrhagic shock are injurious to rat pulmonary microvascular endothelial cells as well as human umbilical vein endothelial cells

Previously, we have documented that gut-derived lymph from rats subjected t o trauma/hemorrhagic shock (T/HS) is injurious to human umbilical vein endo thelial cells (HUVEC). To verify these findings in an all rat systems, the ability of T/HS lymph to increase rat pulmonary microvascular endothelial c ell (RPMVEC) monolayer permeability and kill RPMVEC was compared with that observed with HUVECs. RPMVEcs isolated from male rats or HUVECs were grown in 24-well plates for the cytotoxicity assays or on permeable filters in a two-chamber system for permeability assays. Mesenteric lymph was collected from male rats subjected to trauma (laparotomy) plus hemorrhagic shock (T/H S group) or to a laparotomy plus sham-shock (T/SS group). The T/HS group ha d their mean arterial pressure decreased to 30 mmHg and kept there for 90 m in. Lymph samples centrifuged to remove the cellular component were incubat ed with the RPMVECs or HUVECs at a 10% concentration. Neither T/SS lymph no r post-T/HS portal vein plasma was toxic to or increased the permeability o f the RPMVECs or HUVECs. The pattern of cytotoxicity observed in the HUVECs incubated with T/HS mesenteric lymph was similar to that observed in the R PMVECs, as reflected by trypan blue dye exclusion, with more than 95% of th e HUVECs and RPMVECs being killed after a 16-h incubation with T/HS mesente ric lymph. However, at earlier time points the amount of LDH released from the HUVEC cells incubated with T/HS lymph was greater than that observed wi th the PRMVEC, although trypan blue dye exclusion was similar. Similarly, i ncubation with 10% T/HS lymph increased the permeability of both HUVEC and RPMVEC monolayers more than 2-fold, even with an incubation period as short as 1 h. In conclusion, these results provide further evidence that T/HS ly mph, but not T/SS lymph or post-T/HS portal vein plasma, is injurious to en dothelial cells and that RPMVECs are as susceptible to injury as HUVECs. Ad ditionally, these studies support the emerging concept that gut-induced dis tant organ injury is mediated by factors contained in mesenteric lymph.