Intestinal metabolism after ischemia-reperfusion

Effects of bradykinin preconditioning in an experimental intestinal ischemia reperfusion model on rats

PURPOSE

To investigate the effects of bradykinin on reperfusion injury in an experimental intestinal ischemia reperfusion model.

METHODS

We used 32 Wistar-Albino rats. We composed 4 groups each containing 8 rats. Rats in sham group were sacrified at 100 minutes observation after laparotomy. Thirty minutes reperfusion was performed following 50 minutes ischaemia in control group after observing 20 minutes. Ischaemic preconditioning was performed in one group of the study. We performed the other study group pharmacologic preconditioning by infusional administration of 10 μg/kg/minute bradykinin intravenously. We sacrified all of the rats by taking blood samples to evaluate the lactate and lactate dehydrogenase (LDH) after resection of jejunum for detecting tissue myeloperoxidase (MPO) activity.

RESULTS

Lactate and LDH levels were significantly higher in control and study groups than the sham group (P<0.001). There is no difference between the study groups statistically. (P>0.05). The results were the same for MPO levels. Although definitive cell damage was determinated in the control group by hystopatological evaluation, the damage in the study groups observed was lower in different levels. However, there was no significant difference between the study groups statistically (P>0.05).

CONCLUSION

Either ischeamic preconditioning or pharmacologic preconditioning made by bradykinin reduced the ischemia reperfusion injury at jejunum.

The intestinal injury caused by ischemia-reperfusion is attenuated by amniotic fluid stem cells via the release of tumor necrosis factor-stimulated gene 6 protein

Ischemia/reperfusion (I/R) is implicated in the pathogenesis of various acute intestinal injuries. Amniotic fluid stem cells (AFSC) are beneficial in experimental intestinal diseases. Tumor necrosis factor-induced protein 6 (TSG-6) has been shown to exert anti-inflammatory effects. We aimed to investigate if AFSC secreted TSG-6 reduces inflammation and rescues intestinal I/R injury. The superior mesenteric artery of 3-week-old rats was occluded for 90 minutes and green fluorescent protein-labeled AFSC or recombinant TSG-6 was injected intravenously upon reperfusion. AFSC distribution was evaluated at 24, 48, and 72 hours after I/R. AFSC and TSG-6 effects on the intestine were assessed 48 hours postsurgery. Intestinal organoids were used to study the effects of TSG-6 after hypoxia-induced epithelial damage. After I/R-induced intestinal injury, AFSC migrated preferentially to the ileum, the primary site of injury, through blood circulation. Engrafted AFSC reduced ileum injury, inflammation, and oxidative stress. These AFSC-mediated beneficial effects were dependent on secretion of TSG-6. Administration of TSG-6 protected against hypoxia-induced epithelial damage in intestinal organoids. Finally, TSG-6 attenuated intestinal damage during I/R by suppressing genes involved in wound and injury pathways. This study indicates that AFSC or TSG-6 have the potential of rescuing the intestine from the damage caused by I/R.

Metabolomic profiling of faecal extracts from Cryptosporidium parvum infection in experimental mouse models

Cryptosporidiosis is a gastrointestinal disease in humans and animals caused by infection with the protozoan parasite Cryptosporidium. In healthy individuals, the disease manifests mainly as acute self-limiting diarrhoea, but may be chronic and life threatening for those with compromised immune systems. Control and treatment of the disease is challenged by the lack of sensitive diagnostic tools and broad-spectrum chemotherapy. Metabolomics, or metabolite profiling, is an emerging field of study, which enables characterisation of the end products of regulatory processes in a biological system. Analysis of changes in metabolite patterns reflects changes in biochemical regulation, production and control, and may contribute to understanding the effects of Cryptosporidium infection in the host environment. In the present study, metabolomic analysis of faecal samples from experimentally infected mice was carried out to assess metabolite profiles pertaining to the infection. Gas-chromatography mass spectrometry (GC-MS) carried out on faecal samples from a group of C. parvum infected mice and a group of uninfected control mice detected a mean total of 220 compounds. Multivariate analyses showed distinct differences between the profiles of C. parvum infected mice and uninfected control mice,identifying a total of 40 compounds, or metabolites that contributed most to the variance between the two groups. These metabolites consisted of amino acids (n = 17), carbohydrates (n = 8), lipids (n = 7), organic acids (n = 3) and other various metabolites (n = 5), which showed significant differences in levels of metabolite abundance between the infected and uninfected mice groups (p < 0.05). The metabolites detected in this study as well as the differences in abundance between the C. parvum infected and the uninfected control mice, highlights the effects of the infection on intestinal permeability and the fate of the metabolites as a result of nutrient scavenging by the parasite to supplement its streamlined metabolism.

Metabolomics classifies phase of care and identifies risk for mortality in a porcine model of multiple injuries and hemorrhagic shock

BACKGROUND

Early recognition and intervention in hemorrhagic shock is essential to improved outcomes. However, the lack of robust diagnostic tools readily available to identify patients in the field inhibits the ability to provide timely intervention. Therefore, the development of a reliable prognostic indicator, such as a serum biomarker or a metabolic profile, has significant potential to improve far-forward trauma care. In this study, we used metabolomics as a tool to identify a metabolic state associated with the hemorrhagic shock and outcome in our porcine model of multiple injuries, shock, and resuscitation.

METHODS

Proton nuclear magnetic resonance spectroscopy was used to evaluate serum metabolites from 23 animals that underwent multiple injuries, controlled hemorrhage, and 20 hours of a standard resuscitation protocol. Serum samples were collected from the animals at baseline (before hemorrhage), at shock (after 45 minutes of shock), and at 8 hours of full resuscitation.

RESULTS

We were able to demonstrate shifts in the metabolome throughout different time points and construct a metabolic profile associated with mortality using partial least squares discriminate analysis. The metabolites most responsible for the classification of hemorrhagic shock in our model serve as markers for ischemia, changes in energy production, and cellular damage. Hemorrhagic shock was characterized by marked increases in tricarboxylic acid cycle intermediates, glycolytic-gluconeogenic by-products, purine-pyrimidine catabolism, and fatty acid oxidation.

CONCLUSION

The results of this study demonstrate the potential for metabolomics as a tool to classify the metabolic flux, to identify relevant biochemical pathways, and to identify clinically useful biomarkers.

Development of an untargeted metabolomics method for the analysis of human faecal samples using Cryptosporidium-infected samples

Faecal metabolite profiling, though in its infancy, allows for investigation of complex metabolic interactions between gastrointestinal infections or diseases and host health. In the present study, we describe a faecal metabolite extraction method for untargeted gas chromatography-mass spectrometry (GC-MS) analysis using Cryptosporidium positive and negative human faecal samples. The extraction method takes into account the varying faecal consistencies and quantities received for clinical diagnosis. Optimisation was carried out using different extraction solvents and on three different faecal quantities to determine the minimum amount of faecal sample required. The method was validated by untargeted GC-MS analysis on 8 Cryptosporidium positive and 8 Cryptosporidium negative human faecal samples, extracted using the optimised conditions. The method showed good extraction reproducibility with a relative standard deviation of 9.14%. Multivariate analysis of the GC-MS generated dataset showed distinct differences between profiles of Cryptosporidium positive and Cryptosporidium negative samples. The most notable differences included changes in amino acid, nitrogen and energy metabolism, demonstrating the association of infection with Cryptosporidium and altered permeability of the small intestine.

Proteomic analysis of intestinal ischemia/reperfusion injury and ischemic preconditioning in rats reveals the protective role of aldose reductase

Intestinal ischemia/reperfusion (I/R) injury is a critical condition associated with high morbidity and mortality. Studies show that ischemic preconditioning (IPC) can protect the intestine from I/R injury. However, the underlying molecular mechanisms of this event have not been fully elucidated. In the present study, 2-DE combined with MALDI-MS was employed to analyze intestinal mucosa proteomes of rat subjected to I/R injury in the absence or presence of IPC pretreatment. The protein content of 16 proteins in the intestinal mucosa changed more than 1.5-fold following intestinal I/R. These proteins were, respectively, involved in the cellular processes of energy metabolism, anti-oxidation and anti-apoptosis. One of these proteins, aldose reductase (AR), removes reactive oxygen species. In support of the 2-DE results, the mRNA and protein expressions of AR were significantly downregulated upon I/R injury and enhanced by IPC as confirmed by RT-PCR and western blot analysis. Further study showed that AR-selective inhibitor epalrestat totally turned over the protective effect of IPC, indicating that IPC confers protection against intestinal I/R injury primarily by increasing intestinal AR expression. The finding that AR may play a key in intestinal ischemic protection might offer evidences to foster the development of new therapies against intestinal I/R injury.

Proteomics of ischemia/reperfusion injury in rat intestine with and without ischemic postconditioning

BACKGROUND

Intestinal ischemia/reperfusion (I/R) injury is a critical condition associated with high morbidity and mortality. Our previous study showed that ischemic postconditioning (IPo) protects the intestinal mucosa from I/R injury. However, the precise molecular mechanisms of this event remain poorly elucidated. The aim of this study was to investigate the differentially expressed proteins of intestinal mucosa after intestinal I/R with or without IPo, and to explore the potential mechanisms of intestinal I/R injury and the protective effect of IPo in relation to the differential proteins.

MATERIALS AND METHODS

Intestinal I/R injury was established by occluding the superior mesenteric artery (SMA) for 60 min followed by 60 min reperfusion. The rats were randomly allocated into one of three groups based upon the intervention (n = 8); sham : sham surgical preparation including isolation of the SMA without occlusion was performed; injury: there was no intervention either before or after SMA occlusion; IPo: three cycles of 30 s reperfusion-30 s reocclusion were imposed immediately upon reperfusion. A comparative proteomics approach with two-dimensional gel electrophoresis was used to isolate proteins in intestinal mucosa, the expression of which were regulated by I/R injury post-treated with or without IPo. The differentially displayed proteins were identified through matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS).

RESULTS

Image analysis revealed that an average of 1300 protein spots were detected on each gel; 16 and 9 proteins showing more than 1.5-fold difference were identified between the Sham versus Injury group and injury group versus IPo group, respectively. The identified proteins were functionally involved in the cellular processes of energy metabolism, anti-oxidation, and anti-apoptosis.

CONCLUSIONS

This study provided new clues for understanding the mechanisms of IPo against intestinal I/R injury.

Intestinal ischemia/reperfusion injury: defining the role of the gut microbiome

Intestinal ischemia/reperfusion (I/R) injury initiates a systemic inflammatory response syndrome with a high associated mortality rate. Early diagnosis is essential for reducing surgical mortality, yet current clinical biomarkers are insufficient. Metabonomics is a novel strategy for studying intestinal I/R, which may be used as part of a systems approach for quantitatively analyzing the intestinal microbiome during gut injury. By deconvolving the mammalian–microbial symbiotic relationship systems biology thus has the potential for personalized risk stratification in patients exposed to intestinal I/R. This review describes the mechanism of intestinal I/R and explores the essential role of the intestinal microbiota in the initiation of systemic inflammatory response syndrome. Furthermore, it analyzes current and future approaches for elucidating the mechanism of this condition.

The effects of moderate hypothermia on energy metabolism and serum inflammatory markers during laparotomy

The objective of this study was to investigate energy metabolism of the gut and liver as well as serum inflammatory cytokines following exploratory laparotomy at moderate hypothermia. Two groups of rats were studied, (n=6-8/group); laparotomy at normothermia for 120 min and laparotomy at hypothermia (32-33 degrees C) for 120 min. Study 1: Intestinal glucose, succinate, lactate, phosphocreatine, and ATP as well as hepatic glucose, succinate, lactate, and ATP were measured in terms of micromole per gram using magnetic resonance spectroscopy. Study 2: Serum levels of TNF-alpha, IL-1beta, LPS-inducible chemokine (LIX), and sICAM-1 were measured by ELISA. Histology of the gut and liver were interpreted. Data are expressed as mean and SEM. In Study 1, laparotomy at hypothermia caused an increase in intestinal glucose levels (0.78+/-0.03 vs. 1.29+/-0.11, P=0.0012) with a decrease in hepatic lactate levels (0.82+/-0.04 vs. 0.44+/-0.06, P<0.001). There were no differences in the other metabolites between the two groups. In Study 2, there were no differences in serum TNF-alpha, IL-1beta, LIX, or sICAM-1 between the two groups. Histological features of the gut and liver among groups were comparable. In conclusion, the intestine and liver react to hypothermia differently. However, levels of high-energy phosphates in both organs are not affected by hypothermia suggesting adequate energy for the organs. It is unlikely that hypothermia induces either systemic inflammatory response or hypoxic damage to the intestine and liver in this model.

Amelioration of intestinal reperfusion injury by moderate hypothermia is associated with serum sICAM-1 levels

BACKGROUND

The aim of this study was to investigate the effects of moderate hypothermia on various serum markers involving in inflammation after intestinal ischemia-reperfusion (IR).

MATERIALS AND METHODS

The model of 30 min intestinal ischemia +90 min reperfusion was used. Three groups of rats were studied, n=7-8 per group: 1) sham at normothermia, 36.5 to 37.5 degrees C; 2) IR at normothermia and; 3) IR at moderate hypothermia, 32 to 33 degrees C. Serum levels of TNF-alpha, lipopolysaccharide-inducible CXC chemokine (LIX), and soluble intercellular adhesion molecule-1 (sICAM-1) were determined using ELISA technique. Histological features of terminal ileum were also graded.

RESULTS

Intestinal IR at normothermia caused remarkable tissue injury together with an elevation in serum TNF-alpha, LIX, and sICAM-1 levels. Moderate hypothermia significantly decreased the degree of mucosal damage and attenuated the elevation of serum sICAM-1 levels. However, there were no significant differences in serum TNF-alpha and LIX levels between IR at normothermia and IR at hypothermia.

CONCLUSIONS

Intestinal IR at normothermia induces the elevation of serum TNF-alpha, LIX, and sICAM-1 levels. Moderate hypothermia protects the small intestine from reperfusion injury. This beneficial effect is associated with serum sICAM-1 levels but not with serum TNF-alpha and LIX levels. We speculate that one of the mechanisms, by which hypothermia blunts the tissue injury, is at the step of firm adhesion between leukocytes and endothelial cells.

Biochemical Characterization of Rat Intestine Development Using High-Resolution Magic-Angle-Spinning 1H NMR Spectroscopy and Multivariate Data Analysis

We report details of metabolic profiles for small intestinal samples obtained using high-resolution magic-angle-spinning (HRMAS) (1)H NMR spectroscopy. Intact samples of jejunum and ileum from male Long Evans rats were analyzed on a 600 MHz spectrometer using standard one and two-dimensional (1)H NMR spectroscopic pulse sequences. The metabolic profiles of ileum and jejunum predominantly comprised a number of amino acids, lipids, glycerophosphocholine (GPC), choline, creatine, and ethanol, a number of carboxylic acids including acetate and lactate, and nucleoside bases including cytosine, isocytosine, and uracil. Principal component analysis (PCA) was applied to these NMR data to characterize the biochemical differences between jejunum and ileum tissues. Compared with ileum, jejunum contained higher levels of lipids, GPC, choline, lactate and creatinine, but lower levels of amino acids and acetate. In addition, the age dependence of the biochemical composition of intestinal tissues from young rats (15, 36 days and 3-4 months old) was studied. In general, levels of lipids, lactate, taurine and creatinine were positively correlated with age while amino acids and GPC decreased in the older age group. This study will provide a metabolic reference for further studies assessing the metabolic consequences of nutrition, stress and gut microbiota on intestinal composition.

Effects of intestinal lymph on expression of neutrophil adhesion factors and lung injury after trauma-induced shock

AIM: To study how intestinal lymph after trauma-induced shock (TIS) interferes with expression of neutrophil adhesion factors (CD11b and CD18) and causes lung injury.

METHODS: Thirty-two adult healthy Sprague-Dawley rats were randomly divided into four experimental groups. Groups 1 and 2 included rats with TIS caused by hitting the mid-upper part of both side femoral bones with a 2 500 kg raw-iron, and with or without ligation of mesenteric lymph duct. Groups 3 and 4 included rats with sham-TIS and with or without ligation of mesenteric lymph duct. Expression of neutrophil CD18 and CD11b in at 1 and 3 h after a 90-min TIS/sham-TIS was evaluated. These rats were killed at 3 h after TIS/sham-TIS, and lungs were taken immediately. The main lung injury indexes (the MPO activity and lung injury score) were measured.

RESULTS: The expressions of CD18 and CD11b at 1 and 3 h after a 90-min TIS and the main lung injury indexes were significantly increased compared with those in the sham-TIS groups (P < 0.05). Moreover, at 1 and 3 h after TIS, the expressions of CD18 (32.12 ± 1.25 and 33.46 ± 0.98) and CD11b (29.56 ± 1.35 and 30.56 ± 1.85) were significantly decreased in rats with ligation of mesenteric lymph duct, compared with those (52.3 ± 1.12 and 50.21 ± 1.25, and 42.24 ± 1.24 and 42.81 ± 1.12, respectively) in those without the ligation (all P < 0.05). The main lung injury indexes in rats with TIS with ligation of mesenteric lymph duct (0.96 ± 0.12 and 6.54 ± 0.35) were also significantly decreased, compared with those (1.56 ± 0.21 and 9.56 ± 0.23) in rats with TIS without the ligation (both P < 0.05). However, there was no significant difference in expressions of CD18 and CD11b and the main lung injury indexes between the two sham-TIS groups.

CONCLUSION: Previous ligation of mesenteric lymph ducts prevents or alleviates the up-regulated expression of PMN CD18 and CD11b and the lung injury induced by TIS. Our findings also indicate that neutrophil adhesion molecule activation and lung injury during TIS appear to be caused by some factors that are released or produced by post-ischemic intestine through the mesenteric lymph pathway.

Biochemical and morphological evaluation of Ischemia-Reperfusion injury in rat small bowel modulated by ischemic preconditioning

The objective of this study was to evaluate the effect of ischemic preconditioning upon lesions produced by ischemia-reperfusion of the small intestine. Thirty EPM-1 Wistar rats were randomly distributed into three groups: ischemic preconditioning (IPC; n = 12), ischemia-reperfusion (I/R; n = 12), and control (C; n = 6). Laparotomy permitted isolation of the mesenteric artery for clamping. The animals were heparinized and hydrated. IPC was induced by: 10 minutes of ischemia followed by 10 minutes of reperfusion and then 50 minutes ischemia followed by another 30 minutes reperfusion. Group I/R was submitted to the same protocol except for the 20 minutes of preconditioning. Group C animals underwent only laparotomy for 100 minutes. After reperfusion small intestine fragments were examined histologically. Blood samples were obtained to measure LDH and lactate prior to euthanasia. Lactate values were significantly lower in the IPC as compared to I/R group, 39 versus 67 mg/dL, respectively (P < or =.05). However, neither IPC (grade 3) lesions of the mucosa versus I/R (grade 4) nor LDH values (PCI = 680, I/R = 873 U/L) were statistically different. Thus No morphological evidence of protection was observed following ischemic preconditioning.

The protective effect of moderate hypothermia during intestinal ischemia-reperfusion is associated with modification of hepatic transcription factor activation

BACKGROUND/PURPOSE

Moderate hypothermia throughout intestinal ischemia-reperfusion (IIR) injury reduces multiple organ dysfunction. Heat shock proteins (HSPs) have been shown to be protective against ischemia-reperfusion injury, and STAT (Signal Transducers and Activators of Transcription) proteins are pivotal determinants of the cellular response to reperfusion injury. The aim of this study is to investigate the mechanism of hypothermic protection during IIR.

METHODS

Adult rats underwent intestinal ischemia-reperfusion (IIR), 60-minute ischemia and 60-minute reperfusion, or sham (120 minutes) at either normothermia or moderate hypothermia. Four groups of animals were studied: (1) normothermic sham (NS), (2) normothermic IIR (NIIR), (3) hypothermic sham (HS), and (4) hypothermic IIR (HIIR). Western blotting measured heat shock protein expression, phosphorylated (p-) and total (T-) hepatic STAT-1 and STAT-3.

RESULTS

There were no differences in expression of HSPs 27, 47, 60, i70, c70, or 90 between any of the experimental groups. NIIR caused a significant increase in p-STAT-1 compared with normothermic sham (P <.05) and a highly significant increase in p-STAT-3 (P <.001), both these increases were completely abolished by moderate hypothermia (P <.01 v NIIR.)

CONCLUSIONS

The protective effect of moderate hypothermia on liver is not mediated by HSP expression at this time-point. Hypothermia may act by decreasing hepatic STAT activation, supporting the potential therapeutic role of moderate hypothermia. Modulation of STAT activation may also provide novel therapeutic targets.

Intestinal ischemia and reperfusion injury in growing rats: hypothermia and N-acetylcysteine modulation

Our objective was to evaluate intestinal ischemia-reperfusion injury in growing rats, modulated by hypothermia (I/RH) and N-acetylcysteine (NAC). We used 30 EPM-1 Wistar male rats, aged around 35 days, weighing 90 g. Rats were randomized into 5 groups with 6 animals in each: I/RH group, intestinal ischemia under hypothermia for 40 min and reperfusion for 30 min; I/RH-NAC group, same procedure but adding NAC (150 mg x kg(-1)), previously with ischemia; S-H group, topic hypothermia for 40 min, and observation for 30 min; I/R H-Ve group; and S-NAC group, NAC administration and observation for 70 min. All animals were heparinized and anesthetized with ketamine (60 mg kg(-1)) and xylazine (10 mg kg(-1)) intramuscularly. Surgical procedures were done under microsurgical technique (augmentation, 10x). After laparotomy, the superior mesenteric artery was dissected and clamped to promote ischemia. Topic hypothermia was obtained by using plastic bags at 4 degrees C, changed every 10 min. Rats were sacrificed by exsanguination, and blood samples were utilized to measure D(-)lactate. Intestinal fragments were removed for morphological study. Statistical analysis was done with nonparametric tests (P <or= 0.05). Concerning to D(-)lactate, the data showed biochemical tissue injury, with hypothermia only (S-H = 27 mg/dl), and this became more important when intestinal ischemia and reperfusion were associated to hypothermia (I/RH = 36 mg/dl). NAC decreased ischemia-reperfusion injury (I/RH-NAC = 19 mg/dl). Morphologic tissue injuries, evaluated by hematoxylin-eosin staining, showed grades 4 and 5 for the I/RH and I/RH-Ve groups, respectively, in contrast with other groups (I/RH-NAC = 2, S-H = 1, and S-NAC = 1). Based on our data, we conclude that intestinal ischemia reperfusion injury occurred morphologically as well as functionally, even under hypothermia. However, NAC showed a protective effect on the small bowel from ischemia-reperfusion injury.

Heart energy metabolism after intestinal ischaemia and reperfusion

BACKGROUND/PURPOSE

Multiple organ failure subsequent to intestinal ischaemia and reperfusion (I/R) includes cardiac failure, but little is known about heart energy metabolism in this setting. This study investigates the effects of intestinal I/R on heart energy metabolism and evaluates the effects of moderate hypothermia.

METHODS

Adult rats underwent intestinal ischaemia for 60 minutes followed by 120 minutes of reperfusion. Animals were maintained at either normothermia (36 degrees to 38 degrees C) or moderate hypothermia (30 degrees to 32 degrees C). In experiment A, 2 groups were studied: (1) sham at normothermia; (2) I/R at normothermia. After death, the heart was removed. Cardiac phosphoenergetics were assessed by 31P magnetic resonance spectroscopy; data are expressed as micromoles per gram. In experiment B, 4 groups were studied: (1) sham at normothermia, (2) I/R at normothermia, (3) sham at hypothermia, (4) I/R at hypothermia. At the end of the experiment, the heart was harvested. The activity of carnitine palmitoyl transferase I (CPT I), an important enzyme in the control of fatty acid oxidation, was measured; data are expressed as nanomoles per minute per unit citrate synthase. Results are expressed as mean +/- SEM.

RESULTS

In experiment A, there were no differences between the 2 study groups in cardiac phosphocreatine, inorganic phosphate, adenosine triphosphate (ATP), or in the ratio of inorganic phosphate to ATP. In experiment B, CPT I activity was decreased significantly after I/R at normothermia compared with normothermic sham, but this enzyme inhibition was prevented by hypothermia (3.9 +/- 0.2; v I/R).

CONCLUSIONS

These results suggest that although cardiac ATP supply was maintained during intestinal I/R at normothermia, the balance of substrate utilisation was shifted from fatty acid oxidation to carbohydrate utilisation. However, moderate hypothermia modified these changes. The beneficial effect of moderate hypothermia on cardiac metabolism during intestinal I/R has potential clinical application in various surgical conditions.

Intestinal ischemia reperfusion injury and multisystem organ failure

Intestinal ischemia-reperfusion is a common pathway for many diseases in infants, children, and adults, and this may lead to multiple organ dysfunction syndrome and death. While several studies have investigated reperfusion injury in cardiac, cerebral, and hepatic disease, limited work has been published on intestinal ischemia-reperfusion and its multiorgan effects. The authors have developed models of intestinal ischemia-reperfusion in rats and have demonstrated that intestinal reperfusion causes liver energy failure at normothermia. This is followed by 100% mortality within 4 hours of reperfusion. Moderate hypothermia (32 degrees C to 33 degrees C) induced throughout ischemia and reperfusion prevents liver energy failure, intestinal damage, and neutrophil infiltration in the lungs. Moderate hypothermia in this model of intestinal ischemia and reperfusion prevents mortality. Further studies are needed to establish whether therapeutic hypothermia is a useful intervention in the treatment of infants and children with intestinal injuries caused by ischemia and reperfusion.

Intestinal energy metabolism after ischemia-reperfusion: Effects of moderate hypothermia and perfluorocarbons

PURPOSE

This study investigated the roles of moderate hypothermia and extraluminal oxygenated perfluorcarbon (PFC) on intestinal metabolism after ischemia-reperfusion.

METHODS

A model of 30-minute intestinal ischemia followed by 60 minutes of reperfusion was used. The animals were maintained at either normothermia (36.5 to 37.5 degrees C) or moderate hypothermia (31 to 32 degrees C). Four groups of adult rats were studied (n = 8 per group): (A) sham at normothermia, (B) ischemia-reperfusion at normothermia, (C) ischemia-reperfusion at hypothermia and, (D) ischemia-reperfusion with extraluminal oxygenated PFC perfusion during ischemia at normothermia. Intestinal phosphocreatine, ATP and lactate levels were measured. Histologic changes in the intestine were evaluated.

RESULTS

Intestinal ischemia-reperfusion at normothermia caused a marked reduction in phosphocreatine and ATP with an increase in lactate. Moderate hypothermia exerted beneficial effects by attenuating the depletion of high-energy phosphates and the elevation of lactate. Extraluminal PFC perfusion during ischemia failed to produce a protective effect on high-energy phosphates, although it reduced lactate accumulation. Moderate hypothermia significantly decreased the degree of mucosal damage.

CONCLUSIONS

Whole-body moderate hypothermia protects the small intestine from reperfusion injury as measured both biochemically and histologically. Extraluminal oxygenated PFC administration during ischemia did not protect the intestine from reperfusion injury in this model.

Moderate hypothermia ameliorates liver energy failure after intestinal ischaemia-reperfusion in anaesthetised rats

BACKGROUND/PURPOSE

Intestinal ischaemia-reperfusion (IR) can cause liver failure. The aims of this work were to study the effects of intestinal IR on liver energy metabolism and to evaluate the effects of moderate hypothermia.

METHODS

Intestinal IR (90-minute intestinal ischaemia plus 60-minute or 240-minute reperfusion) was achieved by clamping and unclamping the superior mesenteric artery in rats. Normothermia or moderate hypothermia (30 degrees to 33 degrees C) was maintained by adjusting the environmental temperature. The ratio of hepatic inorganic phosphate to adenosine triphosphate (ATP) was monitored continuously during intestinal IR using in vivo phosphorus ((31)P) magnetic resonance spectroscopy. Phosphorus metabolites also were measured in extracts prepared from freeze-clamped liver and intestine.

RESULTS

Mortality occurred exclusively during normothermic intestinal IR. A progressive increase in the hepatic inorganic phosphate to ATP ratio after normothermic intestinal IR was observed. Moderate hypothermia delayed this effect. Analysis of liver extracts confirmed above findings. However, there was no difference in intestinal phosphocreatine or ATP between normothermic and hypothermic rats undergoing intestinal IR.

CONCLUSIONS

Intestinal IR at normothermia was associated with liver energy failure and high mortality rate. Moderate hypothermia ameliorated liver energy failure but did not attenuate intestinal energy failure after intestinal IR. Hypothermia may prove to be useful in the management of patients with intestinal IR injuries in the future.