Systematic evaluation of nitric oxide, tetrahydrobiopterin, and anandamide levels in a porcine model of endotoxemia.

PURPOSE: Using a lipopolysaccharide (LPS)-treated porcine model, we examined: (1) whether nitric oxide (NO), anandamide, and tetrahydrobiopterin (BH4) increased or not in early endotoxic shock; and (2) the location of the major site of production of these molecules, by comparing their concentrations in arteries and the portal and hepatic veins. METHODS: Ten pigs received an infusion of LPS at 1.7 microg x kg(-1)x h(-1) via the portal vein for 240 min. Consecutive changes in systemic hemodynamics, hepatosplanchnic circulation, and oxygen delivery were measured. Furthermore, the variable changes in the concentrations of nitrite and nitrate (NOx), anandamide, and BH4 were measured. To access the effects of surgery, anesthesia, and fluid management on BH4, an experiment without LPS infusion was performed in two other animals. RESULTS: Mean arterial pressure and cardiac index started to decrease at 60 min after LPS infusion. However, systemic vascular resistance remained unchanged. Total hepatic blood flow and hepatic oxygen delivery also decreased significantly. NOx and anandamide did not change during LPS infusion. BH4 values did not change without LPS infusion. However, BH4 values increased significantly in the arterial, portal, and hepatic circulation during LPS infusion, especially in the hepatic vein (from 136.8 +/- 27.5 to 281.3 +/- 123.2 mol/ml; P < 0.01). CONCLUSION: Our data suggest that the BH4 values were significantly increased in several organs, especially in the liver during endotoxic shock. Impaired cardiac output and decreased blood pressure appeared in the early phase of porcine endotoxemia. Longer-term observation of these parameters after LPS treatment should be performed as the next step in future studies.

Effects of olprinone on hepatosplanchnic circulation and mitochondrial oxidation in a porcine model of endotoxemia.

PURPOSE: This study was performed in order to assess the effects of olprinone, a phosphodiesterase III inhibitor, on hepatic oxygen delivery (DO2H), oxygen consumption (VO2H), and mitochondrial oxidation in the liver of a porcine endotoxemia model. METHODS: Fourteen pigs received continuous infusion of endotoxin via the portal vein for 240 min. From t = 150 to t = 240 min, animals were randomly divided into two groups to receive saline (control [CONT]; n = 7), or olprinone (OLP; n = 7) via the central vein. RESULTS: In the OLP group, prior to olprinone treatment at 150 min, endotoxin induced significant decreases in the cardiac index (CI; from 120 +/- 31 to 65 +/- 13 ml.kg(-1).min(-1); P < 0.01) and DO2H (from 3.58 +/- 0.81 to 1.55 +/- 0.49 ml.kg(-1).min(-1); P < 0.01), while VO2H was maintained. After administration of olprinone (from t = 150 to t = 240 min), CI was unchanged, while DO2H increased from 1.55 +/- 0.49 to 1.93 +/- 0.38 ml.kg(-1).min(-1) (P < 0.01) and VO(2)H increased from 0.42 +/- 0.28 to 0.69 +/- 0.38 ml.kg(-1).min(-1) (P < 0.01). At t = 240 min, the oxidation level of cytochrome aa3 was significantly higher in the OLP group than in the CONT group (OLP, 66.2 +/- 19.3% vs CONT, 26.4 +/- 17.3%; P < 0.01). CONCLUSION: Our data for this porcine endotoxemia model suggest that olprinone may have beneficial therapeutic effects in restoring not only systemic and hepatic circulation but also mitochondrial oxidation in the liver.