Objective: The authors examine the hypothesis that hemorrhage/reperfusion injury predisposes the splanchnic bed to decreased prostacyclin (PGl2) release and blood flow after subsequent endotoxin challenge.
Summary background data: Prostacyclin is a potent vasodilator that has been demonstrated to be an important regulator of splanchnic blood flow. Previous studies have demonstrated that during resuscitation from severe hemorrhage, there is a marked reduction in intestinal PGl2 levels, which is associated with reduced splanchnic perfusion.
Methods: Anesthetized Sprague-Dawley rats underwent hemorrhage to a mean arterial pressure of 30 mmHg for 30 minutes followed by the reinfusion of shed blood. Then the animals were maintained on total parenteral nutrition (TPN) for 10 days, after which time they received 20 mg/kg Escherichia coli endotoxin intraperitoneally. Aortic and superior mesenteric artery (SMA) blood flow was monitored with a Doppler flow probe. The splanchnic bed was excised and perfused in vitro for measurement of venous effluent eicosanoid concentrations. Controls consisted of animals that received TPN and endotoxin but did not undergo hemorrhage and resuscitation (sham).
Results: Total parenteral nutrition support of sham animals followed by endotoxin challenge did not alter splanchnic eicosanoid release or blood flow. Hemorrhage/reperfusion animals supported by long-term TPN and challenged with endotoxin demonstrated a threefold decrease in splanchnic prostacyclin metabolite (6-keto-PGF1 alpha) release and a 50% decrease in SMA blood flow.
Conclusions: Hemorrhage/reperfusion injury predisposes the splanchnic bed from rats sustained with long-term TPN to decreased release of PGl2 and SMA blood flow when challenged with endotoxin as a second injury.