PULMONARY ENDOTHELIAL-CELL ATP DEPLETION FOLLOWING INTESTINAL ISCHEMIA

Multiple organ failure (MOF) is known to follow systemic inflammatory mediator activation associated with intestinal ischemia-reperfusion injury. In particular, the pulmonary microvasculature appears to be susceptible to MOF-related injury. This study was designed to evaluate the hypothesis that non-cellular plasma factors associated with intestinal ischemia without reperfusion also mediate pulmonary endothelial cell injury. Male Sprague-Dawley rats had intestinal ischemia induced by microvascular clip occlusion of the superior mesenteric artery for 30, 60, 90, or 120 min. Following each period of ischemia, plasma samples were obtained from the portal vein. Time-matched sham-operated animals served as controls. Monolayers of cultured rat pulmonary artery endothelial cells were then incubated with the plasma samples and ATP levels determined using a luciferin-luciferase assay. A 51Cr-release assay using labeled endothelial cells was performed under identical conditions to assess cytotoxicity. Endothelial cell ATP levels were 1.99 ± 0.23 × 10-11 mole/μg DNA in sham preparations. After a 4-hr incubation in plasma from the 90 and 120 min ischemia groups, cellular ATP levels fell significantly to 1.07 ± 0.23 × 10-11 mole/μg DNA, respectively (P < 0.005). No significant cytotoxic injury resulted from incubation with plasma from the 120 min group (1.0 ± 0.4% versus 0.8 ± 0.4% in sham group, P = NS). All animals survived 24 hr in the sham, 30, and 60 min groups. However, survival was 40 and 0% in the 90 and 120 min groups, respectively (P < 0.001). These data are consistent with the hypothesis that intestinal ischemia results in the appearance of non-cellular humoral mediators which cause endothelial cell ATP depletion without cellular death, possibly contributing to the pathogenesis of MOF-related acute lung injury. There is a strong correlation of the in vitro data with in vivo survival. © 1992.