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Pulmonary endothelial cell ATP depletion following intestinal ischemia
T M Gerkin1, T H Welling, R H Turnage
1Department of Surgery, University of Michigan Medical School, Ann Arbor 48109.
Abstract:
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 protal 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 x 10(-11) mole/micrograms 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 x 10(-11) mole/micrograms DNA, respectively (P less than 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 less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Plasma factors from intestinal ischemia, without reperfusion, can injure pulmonary endothelial cells. This suggests non-cellular mediators contribute to organ failure, impacting lung microvasculature.
Area of Science:
- Physiology
- Pathology
- Cell Biology
Background:
- Systemic inflammatory mediator activation following intestinal ischemia-reperfusion injury can lead to multiple organ failure (MOF).
- The pulmonary microvasculature is particularly vulnerable to MOF-related damage.
- The role of non-cellular plasma factors in mediating pulmonary endothelial cell injury during intestinal ischemia alone requires further investigation.
Purpose of the Study:
- To investigate the hypothesis that non-cellular plasma factors, present during intestinal ischemia without reperfusion, can cause pulmonary endothelial cell injury.
- To assess the impact of varying durations of intestinal ischemia on plasma-mediated endothelial cell dysfunction.
Main Methods:
- Intestinal ischemia was induced in Sprague-Dawley rats via superior mesenteric artery occlusion for 30, 60, 90, or 120 minutes.
- Plasma samples were collected from the portal vein post-ischemia; sham-operated rats served as controls.
- Cultured rat pulmonary artery endothelial cells were incubated with plasma, and cellular ATP levels and cytotoxicity were assessed.
Main Results:
- Incubation with plasma from rats subjected to 90 and 120 minutes of ischemia significantly reduced endothelial cell ATP levels.
- No significant cytotoxic injury was observed in endothelial cells incubated with plasma from the 120-minute ischemia group.
- Survival rates decreased significantly with longer ischemia durations, with 0% survival at 120 minutes.
Conclusions:
- Non-cellular plasma factors generated during intestinal ischemia, even without reperfusion, can impair pulmonary endothelial cell function.
- These findings suggest a potential mechanism for pulmonary microvascular injury contributing to MOF.
- The duration of intestinal ischemia is critical in determining the severity of plasma-mediated endothelial cell effects and overall survival.