Direct induction of acute lung and myocardial dysfunction by liver ischemia and reperfusion

Effects of Lycopene Attenuating Injuries in Ischemia and Reperfusion

Tissue and organ ischemia can lead to cell trauma, tissue necrosis, irreversible damage, and death. While intended to reverse ischemia, reperfusion can further aggravate an ischemic injury (ischemia-reperfusion injury, I/R injury) through a range of pathologic processes. An I/R injury to one organ can also harm other organs, leading to systemic multiorgan failure. A type of carotenoid, lycopene, has been shown to treat and prevent many diseases (e.g., rheumatoid arthritis, cancer, diabetes, osteoporosis, male infertility, neurodegenerative diseases, and cardiovascular disease), making it a hot research topic in health care. Some recent researches have suggested that lycopene can evidently ameliorate ischemic and I/R injuries to many organs, but few clinical studies are available. Therefore, it is essential to review the effects of lycopene on ischemic and I/R injuries to different organs, which may help further research into its potential clinical applications.

Ischemia-Reperfusion Injury in Peripheral Artery Disease and Traditional Chinese Medicine Treatment

Peripheral artery disease (PAD) is a serious public health issue, characterized by circulation disorder of the lower extreme that reduces the physical activity of the lower extremity muscle. The artery narrowed by atherosclerotic lesions initiates limb ischemia. In the progression of treatment, reperfusion injury is still inevitable. Ischemia-reperfusion injury induced by PAD is responsible for hypoxia and nutrient deficiency. PAD triggers hindlimb ischemia and reperfusion (I/R) cycles through various mechanisms, mainly including mitochondrial dysfunction and inflammation. Alternatively, mitochondrial dysfunction plays a central role. The I/R injury may cause cells' injury and even death. However, the mechanism of I/R injury and the way of cell damage or death are still unclear. We review the pathophysiology of I/R injury, which is majorly about mitochondrial dysfunction. Then, we focus on the cell damage and death during I/R injury. Further comprehension of the progress of I/R will help identify biomarkers for diagnosis and therapeutic targets to PAD. In addition, traditional Chinese medicine has played an important role in the treatment of I/R injury, and we will make a brief introduction.

Effect of silibinin on the expression of MMP2, MMP3, MMP9 and TIMP2 in kidney and lung after hepatic ischemia/reperfusion injury in an experimental rat model

PURPOSE

The protective effect of silibinin on kidney and lung parenchyma during hepatic ischemia/reperfusion injury (IRI) is explored.

METHODS

Sixty-three Wistar rats were separated into three groups: sham; control (45 min IRI); and silibinin (200 μL silibinin administration after 45 min of ischemia and before reperfusion). Immunohistochemistry and real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) were used to evaluate the expression levels of MMP2, MMP3, MMP9, and TIMP2 on kidney and lung.

RESULTS

Comparing sham vs. control groups, confirmed that hepatic IRI increased both renal and lung MMP2, MMP3, MMP9 and TIMP2 expressions starting at 180 min (p<0.001). Comparison of the control vs. silibinin groups showed a statistically significant decrease in the expression levels of MMP2, MMP3, and MMP9 and increase of TIMP2 in kidney and lung parenchyma. The starting point of this decrease was at 120 min after reperfusion, both for kidney and lung parameters, and it was statistically significant at 240 min (p<0.001) for kidney, while silibinin showed a peak of lung protection at 180 min after hepatic reperfusion (p<0.001).

CONCLUSIONS

Hepatic IRI causes distant kidney and lung damage, while a statistically significant protective action, both on kidney and lung parenchyma, is conveyed by the intravenous administration of silibinin.

Tender Coconut Water Protects Mice From Ischemia-Reperfusion-Mediated Liver Injury and Secondary Lung Injury

ABSTRACT

Organ injury by oxidative and inflammatory mediators occurs during ischemia-reperfusion (I/R) of the liver. Remote organ injury secondary to liver I/R increases the systemic insult. Tender coconut water (TCW) has been studied in chemical and fructose-induced liver injury but its ability to decrease tissue injury in clinically relevant injury models is unknown. We evaluated the therapeutic potential of TCW in preventing liver I/R injury and associated remote organ injury. Mice were fed sugar water (SUG; control) or TCW for a week and then subjected to 60 min of liver ischemia followed by reperfusion for 6 h. Plasma alanine transaminase levels, tissue damage, and mRNA levels of Nos2, Tnf, and Il6 were significantly lower in mice fed TCW prior to I/R. Plasma cytokines followed liver cytokine patterns. TCW increased mRNA levels of the anti-oxidant genes Hmox1 and Ptgs2 in the liver of mice subjected to I/R. Remote lung injury from liver I/R was also decreased by TCW feeding as evident by less neutrophil infiltration, decreased pro-inflammatory Il6, and increased anti-inflammatory Il10 mRNA levels in the lung. To examine macrophage activation as a potential mechanism, TCW pretreatment decreased the amount of nitrite produced by RAW264.7 macrophages stimulated with LPS. The levels of Nos2, Il1b, Tnf, and Il6 were decreased while Il10 and Hmox1 mRNA levels were significantly up-regulated upon LPS stimulation of TCW pretreated RAW264.7 macrophages. Collectively, our results indicate that TCW decreased hepatic I/R-mediated damage to liver and lung and suggest that decreased macrophage activation contributes to this effect.

Silibinin Improves TNF-α and M30 Expression and Histological Parameters in Rat Kidneys After Hepatic Ischemia/Reperfusion

BACKGROUND

Remote kidney damage is a sequel of hepatic ischemia-reperfusion (I/R) injury. Silibinin is the main ingredient of the milk thistle plant seed extract with known antioxidant and hepatoprotective activity. Our study investigates the nephroprotective potential of intravenously administered silibinin, as a lyophilized SLB-hydoxypropyl-beta-cyclodextrin product, in hepatic I/R injury.

MATERIAL AND METHODS

63 Wistar rats were divided into three groups: Sham (virtual intervention); Control (45 min ischemia and reperfusion); and Silibinin (200 μL intravenous silibinin administration after 45 min of ischemia). Kidney tissues were collected to determine TNF-α, M30 and histopathological changes at predetermined time intervals.

RESULTS

Comparing Sham vs. Control groups, proved that hepatic I/R injury increased renal TNF-α and M30 expression. Deterioration was observed in hyperemia/filtration of renal parenchyma and tubules, cortical filtration, tubular necrosis and edema (tissue swelling index). Intravenous silibinin administration and comparison of the Control vs. Silibinin groups showed a statistically significant decrease in TNF-α levels at 240 min following I/R (p < 0.0001), and in M30 at 180 min (p = 0.03) and 240 min (p < 0.0001). Renal parameters have significantly decreased in: hyperemia/filtration of renal parenchyma at 120 min (p = 0.003), 180 min (p = 0.0001) and 240 min (p = 0.0002); hyperemia/filtration of renal tubules at 120 min (p = 0.02), 180 min (p = 0.0001) and 240 min (p = 0.0005); cortical filtration (240 min - p = 0.005); tubular necrosis (240 min - p = 0.021); and edema (240 min - p = 0.001).

CONCLUSION

Our study confirms that hepatic I/R injury causes remote renal damage while the intravenous administration of silibinin leads to statistically significant nephroprotective action.

Ischemia/Reperfusion

Ischemic disorders, such as myocardial infarction, stroke, and peripheral vascular disease, are the most common causes of debilitating disease and death in westernized cultures. The extent of tissue injury relates directly to the extent of blood flow reduction and to the length of the ischemic period, which influence the levels to which cellular ATP and intracellular pH are reduced. By impairing ATPase-dependent ion transport, ischemia causes intracellular and mitochondrial calcium levels to increase (calcium overload). Cell volume regulatory mechanisms are also disrupted by the lack of ATP, which can induce lysis of organelle and plasma membranes. Reperfusion, although required to salvage oxygen-starved tissues, produces paradoxical tissue responses that fuel the production of reactive oxygen species (oxygen paradox), sequestration of proinflammatory immunocytes in ischemic tissues, endoplasmic reticulum stress, and development of postischemic capillary no-reflow, which amplify tissue injury. These pathologic events culminate in opening of mitochondrial permeability transition pores as a common end-effector of ischemia/reperfusion (I/R)-induced cell lysis and death. Emerging concepts include the influence of the intestinal microbiome, fetal programming, epigenetic changes, and microparticles in the pathogenesis of I/R. The overall goal of this review is to describe these and other mechanisms that contribute to I/R injury. Because so many different deleterious events participate in I/R, it is clear that therapeutic approaches will be effective only when multiple pathologic processes are targeted. In addition, the translational significance of I/R research will be enhanced by much wider use of animal models that incorporate the complicating effects of risk factors for cardiovascular disease. © 2017 American Physiological Society. Compr Physiol 7:113-170, 2017.

Naloxone pretreatment prevents kidney injury after liver ischemia reperfusion injury

PURPOSE

The aim of this study was to assess the effects of naloxone, an opioid receptor antagonist, on the renal injury as a remote organ after hepatic ischemia reperfusion (IR) in rats.

MATERIALS AND METHODS

Forty male Wistar rats were randomly allocated into four groups as follows: sham, sham + naloxone, IR and IR + naloxone. In anesthetized rats, hepatic ischemia was applied for 30 min in IR and IR + naloxone groups. Sham + naloxone and IR + naloxone groups were given naloxone (3.0 mg/kg, iv) 30 min before ischemia. After 24 h, blood and tissue samples were obtained for histopathological, tissue malondialdehyde (MDA) and biochemical analyses.

RESULTS

Histopathological study of liver in IR group showed enlarged sinusoids, sinusoidal congestion, cellular degenerative changes and necrosis. The kidney of the rats with hepatic IR showed pathological changes in tubular cell swelling, tubular dilatation, moderate to severe necrosis, glomerular fibrosis and hemorrhage. Histological examination confirmed the extent of hepatic and renal changes in IR group was higher (P < 0.05) than in other groups. Rats that underwent hepatic IR exhibited significant increase in serum concentrations of urea and creatinine levels (P < 0.05). The serum alanine aminotransferase and aminotransferase values were significantly higher in IR group compared to the other groups (P < 0.05). Liver IR produced a significant increase in hepatic and renal tissue MDA levels, while pretreatment with naloxone was associated with a significantly lower MDA levels (P < 0.05).

CONCLUSION

The results of this study showed that naloxone pretreatment protected the renal injury from hepatic IR.

Pretreatment with pentoxifylline and N-acetylcysteine in liver ischemia reperfusion-induced renal injury

BACKGROUND AND AIMS

Acute hepatic injury causes systematic inflammatory responses which may finally lead to functional disturbances in remote organs. In this study, the effects of an inhibitor of inflammatory cytokines (pentoxifylline, PTX) and a well-known antioxidant, N-acetylcysteine (NAC), were evaluated on renal damage and oxidative stress following liver ischemia reperfusion (IR).

METHOD

Five groups of six male rats were used. Group 1 was sham operated. In group 2, 90 min liver partial ischemia was induced by a clamp around both hepatic artery and portal vein and then followed by 4 h of reperfusion. In groups 3 and 4, PTX or NAC was injected intraperitoneally before the ischemia, while in group 5 both drugs were co-administered. The levels of alanine amino-transferase (ALT), aspartate amino-transferase (AST), blood urea nitrogen (BUN), and creatinine in serum as well as malonyldialdehyde (MDA) and glutathione (GSH) levels and morphological changes in renal tissues were assessed.

RESULTS

Significant increase in the serum levels of ALT and AST in IR group is indicative of liver functional damages. Elevated BUN and renal tissue MDA, decreased GSH levels, and morphological damages in IR group demonstrate a significant kidney injury and oxidative stress comparing to sham group. Administration of PTX alone and PTX + NAC prevented the IR-induced increase in renal MDA levels. Administration of both drugs and their co-administration prevented the reduction in renal GSH levels and morphological changes.

CONCLUSION

Pretreatment with PTX and NAC before liver IR may be useful to ameliorate renal oxidative damage by preservation of cellular GSH concentration and a reduction in MDA levels.

Oxidants as important determinants of renal apoptosis during pneumoperitoneum: a study in an isolated perfused rat kidney model

INTRODUCTION

Pneumoperitoneum-associated ischemia-reperfusion (IR) may initiate renal dysfunction. Whether oxidants are responsible for renal structural damage, such as cell apoptosis, has not yet been evaluated. We investigated such eventuality in an isolated rat kidney model.

METHODS

Thirty-five rat kidneys with their vessels and ureter were harvested and perfused within a closed environment at flow of 15 ml min(-1). After stabilization, kidneys were assigned to one of five groups (n = 7 per group): CO(2)-induced intrachamber pressure of 8, 12, or 0 mmHg (control), and 8 or 12 mmHg pressure applied to kidneys from rats treated pre-experimentally with tungsten for 14 days. Pressurization lasted 60 min.

RESULTS

Organ perfusion pressure raised as intrachamber pressure increased. Urinary output decreased in the two pressurized nonpretreated groups. Intrachamber pressure was directly associated with an increase in postexperimental xanthine oxidase tissue levels. Twofold apoptosis was documented (p < 0.05) in cortex of nonpretreated kidney in the 12 mmHg group compared with the 8 or 0 mmHg groups. Tungsten pretreatment significantly (p < 0.05) attenuated the abnormalities documented in the 12 mmHg group, but less so in the 8 mmHg pressurized nontreated counterparts.

CONCLUSIONS

Pneumoperitoneal pressure applied to isolated perfused kidney is associated with renal apoptosis. This rapidly induced structural renal damage is oxidant dependent and can be attenuated by antioxidants. Further studies may shed more light on the role of antioxidants in preventing pneumoperitoneum-induced kidney dysfunction.

Sphingosine-1-phosphate reduces hepatic ischaemia/reperfusion-induced acute kidney injury through attenuation of endothelial injury in mice

AIM

Hepatic ischaemia/reperfusion injury (IRI) frequently complicates acute kidney injury (AKI) during the perioperative period. This study was to determine whether hepatic IRI causes AKI and the effect of the sphingosine-1-phosphate (S1P) on AKI.

METHODS

S1P and vehicle were given to mice before ischaemia and mice were subjected to hepatic IRI. Plasma creatinine (PCr), alanine transaminase (ALT), urinary neutrophil gelatinase-associated lipocalin (NGAL) and renal histological changes were determined. As a marker of endothelial injury, vascular permeability was measured. The effect of VPC 23019, a S1P(1) receptor antagonist, was also assessed.

RESULTS

Hepatic IRI resulted in liver injury (increased ALT) and systemic inflammation. Kidneys showed elevated inflammatory cytokines, leucocyte infiltration, increased vascular permeability, tubular cell apoptosis and increased urinary NGAL, although PCr did not increase. Pretreatment with S1P resulted in an attenuation of systemic inflammation and kidney injury without any effect on plasma ALT or peripheral lymphocytes. The protective effect of S1P was partially reversed by VPC 23019, suggesting the important contribution of the S1P/S1P(1) pathway to protect against hepatic IRI-induced AKI.

CONCLUSION

The study data demonstrate the important contribution of systemic inflammation and endothelial injury to AKI following hepatic IRI. Modulation of the S1P/S1P(1) receptor pathway might have some therapeutic potential in hepatic IRI-induced kidney injury.

Preoperative fasting protects mice against hepatic ischemia/reperfusion injury: mechanisms and effects on liver regeneration

We show that brief periods of fasting induce functional changes similar to those induced by long-term dietary restriction in mice, and these changes include protection from ischemia/reperfusion (I/R) injury. In this study, we investigated the mechanisms of protection induced by fasting, and we determined the effect on liver regeneration after partial hepatectomy. Partial hepatic ischemia (75 minutes) was induced in ad libitum fed mice and in 1- to 3-day-fasted mice, and one-third or two-thirds hepatectomy was performed in ad libitum fed mice and 3-day-fasted mice. Preoperative fasting for 2 or 3 days significantly decreased hepatocellular I/R injury. Hepatic gene expression of heme oxygenase 1 (HO-1), superoxide dismutase 2 (SOD2), glutathione peroxidase 1 (Gpx1), and glutathione reductase (GSR) was significantly up-regulated in 3-day-fasted mice at the baseline and 6 hours after reperfusion. After reperfusion, p-selectin and interleukin-6 (IL-6) levels were significantly lower, and superoxide radical generation, lipid peroxidation, and neutrophil influx were significantly attenuated in 3-day-fasted mice. Preoperative fasting did not affect liver regeneration after one-third hepatectomy. Hepatic gene expression of IL-6 and transforming growth factor β1 was significantly higher in 3-day-fasted mice before and after one-third hepatectomy. Tumor necrosis factor α expression significantly increased after one-third hepatectomy in 3-day-fasted mice. After a 3-day fast and two-thirds hepatectomy, liver regeneration and subsequent postoperative recovery were compromised. In conclusion, up-regulation of the stress response gene HO-1 and the antioxidant enzymes SOD2, Gpx1, and GSR at the baseline and a better response after reperfusion likely underlie the protection induced by fasting against hepatic I/R injury. Preoperative fasting may be a promising new strategy for protecting the liver against I/R injury during liver transplantation and minor liver resections, although its effect on extended hepatectomy warrants further exploration.

Early myocardial injury is an integral component of experimental acute liver failure - a study in two porcine models

INTRODUCTION

There is accumulating clinical evidence that acute liver failure may be regularly associated with myocardial injury. To test this hypothesis in a standardized experimental setting, we used two porcine models of ALF.

MATERIAL AND METHODS

In 14 domestic pigs ALF was induced by either a) surgical devascularization of the liver (DV group, n = 7), or b) partial (70-75%) hepatectomy and ischaemia/reperfusion of the liver remnant for 150 min (I/R group, n = 7). Four additional animals constituted the sham operation group. All animals were monitored for a 12-h period, at the end of which their hearts were harvested. Plasma troponin I (cTnI) and malondialdehyde (MDA) were measured before the operation (baseline) and at 6 h and 12 h postoperatively. The harvested hearts were histologically analysed, appointing a score from 0 (no injury) to 3 (maximum injury) to selected injury indicators.

RESULTS

In the sham group, all cTnI measurements and total myocardial injury score were zero in all animals. In both ALF groups, plasma cTnI levels increased by the 6(th) and remained elevated up to the 12(th) postoperative hour (p < 0.01 vs. sham animals). Total myocardial injury score and total histological score revealed some extent of myocardial injury. The rise of MDA levels suggests an underlying oxidative mechanism.

CONCLUSIONS

Our study provides direct evidence of early myocardial injury in the setting of acute liver failure in pigs. The mechanism of injury remains to be elucidated.

Selective intrarenal human A1 adenosine receptor overexpression reduces acute liver and kidney injury after hepatic ischemia reperfusion in mice

Acute kidney injury (AKI) is frequent after liver ischemia reperfusion (IR) can potentiate liver injury and is often complicated by subsequent multiorgan dysfunction syndrome. AKI because of liver IR is characterized by early renal endothelial cell apoptosis and impaired vascular integrity with subsequent neutrophil infiltration, proximal tubule necrosis/inflammation, and filamentous (F) actin disintegration. We tested whether selective renal overexpression of human A(1) adenosine receptors (huA(1)AR) protects against both liver and kidney injury sustained after liver IR. Mice were subjected to liver IR or to sham surgery 48 h after unilateral intrarenal injection of lentivirus encoding enhanced green fluorescent protein (EGFP) or EGFP-huA(1)AR. Intrarenal lentiviral gene delivery caused a robust transgene expression in the injected kidney without significant expression in the contralateral kidney or in the liver. Mice injected with EGFP-huA(1)AR lentivirus were protected against hepatic IR-induced liver and kidney injury with reduced necrosis, inflammation, and apoptosis, and better preserved F-actin and vascular permeability compared with mice injected with EGFP lentivirus. Importantly, we show that removing the EGFP-huA(1)AR lentivirus-injected kidney before hepatic ischemia abolished both renal and hepatic protection after liver IR showing that the overexpression of huA(1)AR in the injected kidney has a crucial role in protecting the kidney and liver after liver IR. Therefore, our findings show that protecting the kidney reduces liver IR injury and selective overexpression of cytoprotective A(1)ARs in the kidney leads to protection of both liver and kidney after hepatic IR.

Growth factor and receptor mRNA expression in the intestine of horses with large colon volvulus: a pilot study

REASONS FOR PERFORMING STUDY

Growth factors (GF) are important for maintenance and repair of intestinal mucosal structure and function, but there have been no studies investigating growth factor (GF) or growth factor receptor (GF-R) mRNA expression in the intestine of horses with large colon volvulus (LCV).

OBJECTIVES

(1) To determine mRNA expression for epidermal growth factor (EGF), EGF receptor (EGF-R), insulin-like growth factor-I (IGF), IGF receptor (IGF-R), vascular endothelial growth factor (VEGF) and VEGF receptor (VEGF-R) in the intestine of horses with an LCV compared to normal intestine. (2) To measure the correlation between histological intestinal injury and mRNA expression.

METHODS

In 5 horses, samples were collected from the mid-jejunum (small intestine, SI), pelvic flexure (PF) and right dorsal colon (RDC) prior to creation of the LCV (NORM), 1 h following creation of the LCV (ISCH) and 1 h following correction of the LCV (REPER). In 2 clinical cases of LCV, samples were collected from the PF and RDC. Samples were assessed histologically for the amount of intestinal injury. The mRNA expressions of growth factors and receptors were determined using qRT-PCR.

RESULTS

VEGF and VEGF-R mRNA expression was greater in horses with an LCV compared to NORM. Expression of IGF-R mRNA increased in the SI during ISCH and REPER.

CONCLUSION AND POTENTIAL RELEVANCE

The increase compared to NORM in VEGF and VEGF-R mRNA expression in horses with LCV may be important in early intestinal healing and may also explain, in part, the increase in vascular permeability in horses with a LCV. Expression of IGF and IGF-R in the SI warrants further investigation and may be important for understanding post operative complications in horses with SI lesions.

Methylene blue attenuates pancreas ischemia-reperfusion (IR)-induced lung injury: a dose response study in a rat model

BACKGROUND

Oxidants (and their generator, xanthine oxidase [XO]) play a role in inducing acute lung injury (ALI) expressed both structurally and functionally. Such damage has recently been demonstrated in the presence of pancreas ischemia-reperfusion (IR). We now investigated whether methylene blue (MB), a clinically used coloring agent and antioxidant in itself, protected the lung exposed to pancreas IR.

MATERIALS AND METHODS

Isolated pancreata (eight replicates/group) were (1) continuously perfused (controls), (2) made ischemic (IR-0) for 40 min and reperfused without treatment, (3) organs procured from allopurinol-treated rats made ischemic and reperfused with allopurinol, and (4) made ischemic and treated upon reperfusion with three different doses of MB contained in the perfusate. All perfusate solutions were directed into the isolated lungs' circulation whereby they were perfused for 60 min.

RESULTS

Pancreas injury was documented in all IR organs by abnormally high reperfusion pressure, wet-to-dry ratio, amylase and lipase concentrations, and abnormal XO activity and reduced glutathione in the circulation. Lungs paired with IR-0 pancreata developed approximately 60% increase in ventilatory plateau pressure and final PO(2)/FiO(2) decrease by 35%. Their weight during reperfusion and bronchoalveolar lavage (BAL) volume and contents increased 1.5-2.5 times the normal values; XO and reduced glutathione values were abnormal both in the BAL and in the lung tissues. Lungs exposed to IR effluents containing allopurinol or 68 microM MB were minimally damaged, whereas perfusion solutions containing 42 or 128 microM MB were ineffective in preventing lung injury.

CONCLUSIONS

Ex vivo pancreas IR-induced ALI is preventable by MB, although at a narrow dose range.

Human activated protein C attenuates both hepatic and renal injury caused by hepatic ischemia and reperfusion injury in mice

Hepatic ischemia and reperfusion (IR) injury is a major clinical problem often leading to acute kidney injury characterized by early endothelial cell apoptosis, subsequent neutrophil infiltration, proximal tubule necrosis/inflammation, impaired vascular permeability, and disintegration of the proximal tubule filamentous actin cytoskeleton. Activated protein C is a major physiological anticoagulant with anti-inflammatory and anti-apoptotic activities in endothelial cells. Here we tested if activated protein C would attenuate hepatic and renal injury caused by hepatic ischemia and reperfusion. Both liver and kidney injury were significantly reduced when activated protein C was given immediately before and 2 h after liver reperfusion, in that there was reduced renal endothelial and hepatocyte apoptosis, as well as reduced hepatic and renal tubular necrosis. Further, the administration of activated protein C also reduced the expression of several pro-inflammatory genes, liver and kidney filamentous-actin degradation, and neutrophil infiltration, and resulted in better preservation of vascular permeability of both the liver and kidney than is normally seen after liver ischemia and reperfusion. These protective effects of activated protein C were due to protease-activated receptor-1 modulation since administration of a selective receptor antagonist dose-dependently inhibited its ameliorative effects in both organs after liver ischemia and reperfusion. Our results suggest the powerful multi-organ protective effects of activated protein C may improve outcome in those patients at significant risk of developing acute kidney injury following liver ischemia and reperfusion during transplantation.

Mannitol prevents acute lung injury after pancreas ischemia-reperfusion: a dose-response, ex vivo study

Oxidants and their generator, xanthine oxidase (XO), play a major role in the damaging of the structural and functional integrity of the lung. Such damage has been recently demonstrated in the presence of pancreas ischemia-reperfusion (IR). We investigated whether mannitol, a clinically used agent and antioxidant, prevented lung damage after pancreas IR. Rats (n = 48) were anesthetized, after which each pancreas was isolated and perfused (controls), or made ischemic (IR) for 40 min, or made ischemic and treated upon reperfusion with four different doses of mannitol administered in the perfusate (8 replicates/group). Ischemia was followed by in-series 15-min pancreas plus normal isolated lung reperfusion. Isolated lungs were subsequently perfused for 45 min with the 15-min accumulated effluents. Pancreas injury occurred in all IR organs as demonstrated by abnormal reperfusion pressure, the wet-to-dry ratio, amylase and lipase leakage into the circulation, and XO activity and reduced glutathione (GSH) pool in the tissues. Pulmonary plateau pressure increased by 80%, and final PO(2)/FiO(2) decreased by 28% in the IR-untreated paired lungs. Bronchoalveolar lavage volume increased by 50% and 2- to 8-fold increase in their contained XO and GSH were recorded as well. The above indices of injury in lungs perfused with 0.77 mM mannitol were the least detected, compared with negligible efficacy of other (0.55 < 0.22 < 1.1 mM) dosages. Amylase and lipase did not contribute to lung injury. Ex vivo acute pancreatitis induces acute lung injury via oxidants/antioxidants imbalance, which is preventable by mannitol.

Acute kidney injury after hepatic ischemia and reperfusion injury in mice

Hepatic ischemia reperfusion (IR) is the leading cause of acute liver failure (ALF) during the perioperative period and patients with ALF frequently develop acute kidney injury (AKI). There is no effective therapy for AKI associated with ALF because pathomechanisms are incompletely characterized, in part due to the lack of an animal model. In this study, we characterize a novel murine model of AKI following hepatic IR. Mice subjected to approximately 70% liver IR not only developed acute liver dysfunction, but also developed severe AKI 24 h after liver injury. Mice subjected to liver IR developed histological changes of acute tubular injury including focal proximal tubular cell necrosis involving the S3 segment, cortical tubular ectasia, focal tubular simplification and granular bile/heme cast formation. In addition, there was focal interstitial edema and hyperplasia of the juxtaglomerular apparatus. Inflammatory changes in the kidney after hepatic IR included neutrophil infiltration of the interstitium and upregulation of several proinflammatory mRNAs (tumor necrosis factor-alpha, keratinocyte-derived cytokine, monocyte chemotactic protein-1, macrophage inflammatory protein-2, intercellular adhesion molecule-1). In addition, marked renal endothelial cell apoptosis was detected involving peritubular interstitial capillaries, accompanied by increased renal vascular permeability. Finally, there was severe disruption of renal proximal tubule epithelial filamentous-actin. Our results show that AKI rapidly and reproducibly develops in mice after hepatic IR and is characterized by renal tubular necrosis, inflammatory changes and interstitial capillary endothelial apoptosis. Our murine model of AKI after liver injury closely mimics human AKI associated with ALF and may be useful in delineating the mechanisms and potential therapies for this common clinical condition.

Mannitol attenuates kidney damage induced by xanthine oxidase-associated pancreas ischemia-reperfusion

BACKGROUND

Ischemia and subsequent reperfusion (IR) may induce local and remote organ reperfusion injury. It may be propagated by xanthine oxidase (XO)-generated oxidant stress. We investigated whether pancreas IR directly and acutely induces renal dysfunction and if this outcome could be prevented by mannitol.

MATERIALS AND METHODS

Rat pancreases were isolated and perfused with Krebs-Henseleit solution enriched with 5% bovine albumin. Other rats donated kidneys that were perfused at constant pressure mode. Each pancreas underwent 45 min of either perfusion (control) or ischemia (no flow). Both organ perfusion systems were then combined and the kidneys were perfused with the pancreatic 15-min reperfusate for 2 h. A third group consisted of paired ischemic pancreases and nonischemic kidneys treated with mannitol 250 mg/kg body weight during reperfusion.

RESULTS

The controls demonstrated no abnormal perfusion or metabolite changes. Pancreas and renal perfusion pressures increased by >50% in the ischemia group immediately upon reperfusion; it remained above the values of controls during the 2-h kidney reperfusion. Conversely, perfusion pressure in the treatment group was not significantly different from the control. The reduced glutathione level increased significantly, as did XO, immediately upon starting reperfusion in both organs appertaining to the ischemic group; this misbalance was not documented in the controls and the mannitol-treated groups. Urine output was severely reduced in the IR kidneys.

CONCLUSION

Ischemia/reperfusion of the rat pancreas evokes immediate renal dysfunction. Kidney oxidant-antioxidant balance is disturbed, but can be prevented with mannitol. These two figures underline the role of oxidative stress in promoting acute renal damage in the presence of pancreas IR.

Ischemia of the lung causes extensive long-term pulmonary injury: an experimental study

Background

Lung ischemia-reperfusion injury (LIRI) is suggested to be a major risk factor for development of primary acute graft failure (PAGF) following lung transplantation, although other factors have been found to interplay with LIRI. The question whether LIRI exclusively results in PAGF seems difficult to answer, which is partly due to the lack of a long-term experimental LIRI model, in which PAGF changes can be studied. In addition, the long-term effects of LIRI are unclear and a detailed description of the immunological changes over time after LIRI is missing. Therefore our purpose was to establish a long-term experimental model of LIRI, and to study the impact of LIRI on the development of PAGF, using a broad spectrum of LIRI parameters including leukocyte kinetics.

Methods

Male Sprague-Dawley rats (n = 135) were subjected to 120 minutes of left lung warm ischemia or were sham-operated. A third group served as healthy controls. Animals were sacrificed 1, 3, 7, 30 or 90 days after surgery. Blood gas values, lung compliance, surfactant conversion, capillary permeability, and the presence of MMP-2 and MMP-9 in broncho-alveolar-lavage fluid (BALf) were determined. Infiltration of granulocytes, macrophages and lymphocyte subsets (CD45RA⁺, CD5⁺CD4⁺, CD5⁺CD8⁺) was measured by flowcytometry in BALf, lung parenchyma, thoracic lymph nodes and spleen. Histological analysis was performed on HE sections.

Results

LIRI resulted in hypoxemia, impaired left lung compliance, increased capillary permeability, surfactant conversion, and an increase in MMP-2 and MMP-9. In the BALf, most granulocytes were found on day 1 and CD5⁺CD4⁺ and CD5⁺CD8⁺-cells were elevated on day 3. Increased numbers of macrophages were found on days 1, 3, 7 and 90. Histology on day 1 showed diffuse alveolar damage, resulting in fibroproliferative changes up to 90 days after LIRI.

Conclusion

The short-, and long-term changes after LIRI in this model are similar to the changes found in both PAGF and ARDS after clinical lung transplantation. LIRI seems an independent risk factor for the development of PAGF and resulted in progressive deterioration of lung function and architecture, leading to extensive immunopathological and functional abnormalities up to 3 months after reperfusion.

Remote renal injury following partial hepatic ischemia/reperfusion injury in rats

Liver ischemia/reperfusion has been shown to result in injury of remote organs such as the heart and lungs. Whether or not acute liver injury also results in kidney injury has so far not been adequately addressed. In anesthetized Wistar rats, partial (70%) normothermic hepatic ischemia was applied for 75 min. After 24 h of reperfusion, renal injury was assessed by histology, creatinine and blood urea nitrogen (BUN) serum concentrations, renal expression of proinflammatory genes [quantitative real-time polymerase chain reaction (qRT-PCR)], caspase-3 activation (Western blot), and neutrophil accumulation (myeloperoxidase assay). Twenty-four hours after hepatic ischemia, creatinine (0.57+/-0.06 vs. 0.32+/-0.04 mg/dL) and BUN (40.7+/-15.3 vs. 14.3+/-2.0 mg/dL) were increased when compared to sham. qRT-PCR revealed higher renal intercellular adhesion molecule-1 gene expression following hepatic ischemia (166+/-45% when compared to sham) but no differences in renal monocyte chemoattractant protein-1, macrophage inflammatory protein-2, and inducible NO synthase expression. In both groups, kidneys showed no morphological damage and no increase in caspase-3 and myeloperoxidase activity. Severe hepatic ischemia results in a moderate impairment of renal function in rats but does not trigger an inflammatory response in the kidney and does not result in morphological damage of the kidney.

Acute lung injury following pancreas ischaemia-reperfusion: role of xanthine oxidase

BACKGROUND

Acute pancreatitis can lead to increased pulmonary vascular permeability and respiratory failure. Oxidants (and their generator, xanthine oxidase (XO)) play an important role in injuring the structural integrity of the pulmonary epithelium and endothelium, but their importance in the induction of acute lung injury following pancreas ischaemia-reperfusion (IR) has not been defined.

MATERIALS AND METHODS

Rats (n = 48) received a regular or a tungsten (oxidoreductase inhibitor)-enriched diet for 14 days. Their isolated pancreases were then either perfused (controls) or made ischaemic (IR) for 40 min (12 replicates/group). This was followed by in-series pancreas plus normal isolated lung reperfusion for 15 min. Lungs only were subsequently perfused with the 15-min accumulated pancreas effluents for 45 min.

RESULTS

Injury was induced in all IR pancreases as expressed by reperfusion pressure, wet-to-dry ratio and amylase and lipase concentrations. Tissue XO activity was high and reduced glutathione pool was low in the tungsten-free IR pancreases. Pulmonary plateau pressure increased by 46% and final PO(2)/FiO(2) decreased by 24%. Capillary pressure and weight rose two- to fourfold in lungs paired with IR non-treated pancreases. Twofold increases in bronchoalveolar lavage volume and contents, including XO, were also recorded in this group of lungs. Lungs exposed to tungsten-treated ischaemic pancreas effluents were minimally damaged and tissue XO content was low compared to controls.

CONCLUSIONS

Ex-vivo acute pancreatitis induces acute lung injury via oxidants/antioxidants misbalance, which may be prevented by attenuating pancreas oxidative stress.

Vascular dysfunction in ischemia-reperfusion injury

Microvascular dysfunction mediates many of the local and systemic consequences of ischemic-reperfusion (I/R) injury, with a spectrum of changes specific to arterioles, capillaries, and venules. This review discusses the specific changes in the endothelium during I/R injury; describes the differential responses of the various levels of the vasculature including arterioles, capillaries, and venules; and explores mechanisms for remote organ injury. Vascular dysfunction is largely a consequence of changes in the endothelial cells themselves, affecting the integrity of barrier function, cytokine and adhesion molecule expression, and vascular tone. The bioavailability of nitric oxide, an important mediator of vasodilation, is profoundly decreased during the reperfusion period, resulting in impaired vasodilation of arterioles. Release of inflammatory mediators and increased expression of adhesion molecules initiate inflammatory and coagulation cascades that culminate in the occlusion of capillaries, known as the "no-reflow''" phenomenon. In postcapillary venules, the recruitment and transmigration of leukocytes further compromise the integrity of the endothelial barrier and increase the oxidative burden, resulting in leakage and tissue edema. I/R injury can have significant and untoward consequences beyond the affected tissue, with such conditions as systemic inflammatory response syndrome. This review highlights recent progress in understanding of the varied phenomena of vascular dysfunction in I/R injury and some promising advances in the understanding and application of ischemic preconditioning and other potential therapies.

TPEN attenuates hepatic apoptotic ischemia/ reperfusion injury and remote early cardiac dysfunction

The release of cardioactive substances during hepatic ischemia/reperfusion injury generates toxic free radicals that inflict hepatic and remote cardiac damage. The aim of the study was to determine whether TPEN, a potent iron chelator, ameliorates the apoptotic hepatic and cardiac function injuries. Three groups of isolated rat livers were studied: (1) continuously perfused with Krebs-Henseleit solution; (2) subjected to 120 min of ischemia and 15 min of reperfusion; (3) as in group 2, with TPEN administered prior to ischemia. Isolated hearts were perfused for 65 min with the effluent of the reperfused livers. Results showed that TPEN administration reduced the release of norepinephrine, epinephrine, dopamine, prostaglandin E2 and angiotensin II, decreased intrahepatic caspase-3 activity, and decreased the mean hepatocyte apoptotic index (TUNEL assay) (p = 0.001). Perfusion with post-ischemic hepatic effluent caused a transient 15-min increase in left ventricular contraction and coronary flow (p < 0.05), followed by a decrease in cardiac function at one hour. TPEN reduced the transient elevation in left ventricular contraction p < 0.05), but did not prevent the subsequent decrease in cardiac function. In conclusion, TPEN attenuates post-ischemic apoptotic hepatic injury by modulating caspase-3-like activity and reduces the cardioactive substances released from the liver.

N-Acetyl-L-Cysteine Mitigates Aortic Tone Injury Following Liver Ischemia-Reperfusion

Liver ischemia and subsequent reperfusion (IR) are associated with secondary, remote organ reperfusion injury attributable to oxidative stress mediators. Because N-acetyl-L-cysteine (NAC) was effective in attenuating lung reperfusion injury, its properties on aortic dysfunction were tested. Rat isolated perfused aortic rings (n = 8/group) were evaluated during and after exposure to liver postischemia perfusate. Aortic response to phenylephrine under these conditions was also assessed in the presence or absence of increasing concentrations of NAC. Aortic rings incubated with postischemia perfusates exhibited abnormally protracted contraction. Their response to phenylephrine was reduced to 18 +/- 7% and 65 +/- 11% of controls during and after the exposure, respectively, and their subsequent relaxation was irregular. NAC 0.25 mM best attenuated the IR-induced aortic tone impairments, 0.12 mM affected it slightly, and IR-NAC 0.5 mM and IR-NAC 0.74 mM solutions dilated the rings proportionately, abolishing reactions to both IR solutions and phenylephrine. Xanthine oxidase activity and reduced glutathione (GSH) level in all IR ring tissues were inversely proportionate, but not directly so. Thus, liver IR impaired aortic tone and its response to phenylephrine, even after removal of toxic elements. NAC concentrations directly and inversely correlated with xanthine oxidase activity but not with GSH level. It preserved aortic functions dose-specifically, mainly by oxidant quenching.

Adenosine A2A Receptor Agonist Improves Cardiac Dysfunction From Pulmonary Ischemia-Reperfusion Injury

BACKGROUND

Ischemia-reperfusion (IR) injury negatively impacts patient outcome in lung transplantation. Clinically, we observed that lung transplant patients with ischemia-reperfusion injury tend to have cardiac dysfunction. Previous studies have shown that ATL-146e (4-{3-[6-amino-9-(5-ethylcarbamoyl-3,4-dihydroxy-tetrahydro-furan-2-yl)-9H-purin-2-yl]-prop-2-ynyl}-cyclohexanecarboxylic acid methyl ester), a selective adenosine A2A receptor agonist, reduces lung inflammation after ischemia-reperfusion. We hypothesized that pulmonary ischemia-reperfusion causes secondary heart dysfunction and ATL-146e will improve this dysfunction.

METHODS

We utilized an in vivo rabbit lung ischemia-reperfusion model. The Sham group underwent 120 minutes single lung ventilation. The IR and ATL groups underwent 90 minutes right lung ischemia with 30 minutes right lung reperfusion. The ATL-146e was given intravenously to the ATL group during reperfusion. Cardiac output and arterial blood gases were monitored, and neutrophil sequestration was measured by myeloperoxidase activity.

RESULTS

Upon reperfusion, cardiac output (mL/min) significantly dropped in the IR and ATL groups. By 15 minutes reperfusion, cardiac output in the ATL group improved significantly over the IR group and remained significant thereafter. Lung myeloperoxidase activity was significantly reduced by ATL-146e. Although never hypoxemic, arterial oxygenation was lower in the IR and ATL groups while central venous pressures and mean arterial pressures were similar among groups. A separate experiment demonstrated that reperfusion with the antioxidant N-(2-mercaptopropionyl)glycine prevented cardiac dysfunction.

CONCLUSIONS

Pulmonary ischemia-reperfusion causes cardiac dysfunction independent of preload, afterload, and oxygenation. The ATL-146e improves this dysfunction presumably by the antiinflammatory effects of adenosine A2A receptor activation on neutrophils. One likely mechanism involves the release of oxidants from the ischemic lung upon reperfusion, which has immediate negative effects on the heart.

Reversible myocardial dysfunction in critically ill, noncardiac patients: a review

OBJECTIVE

To review reversible myocardial dysfunction affecting critically ill patients without cardiac pathology.

DATA SOURCES

The bibliography for the study was compiled through a search of different databases for the period 1966-2001. References cited in the selected articles also were reviewed.

STUDY SELECTION

The selection criteria included all articles published on reversible myocardial dysfunction in critically ill patients.

CONCLUSIONS

Reversible myocardial dysfunction may develop in a situation of critical pathology, but the etiology of reversible myocardial dysfunction is not fully understood. This dysfunction may be accompanied by increases in enzyme concentrations and electrocardiographic changes. Reversible myocardial dysfunction probably is underdiagnosed, although its presence is associated with a worsening of the prognosis and with more specific therapeutic options. Further studies are necessary to define its true incidence and clinical implications.

Impairment of aortal tone by no flow-reflow conditions and its partial amelioration by mannitol

BACKGROUND

Although postischemic cardiac or pulmonary dysfunction can relate to the impact of remotely generated oxygen stress mediators on the heart, their direct effect on the vascular bed remains unresolved. Thus, we tested these remote effects in an ex-vivo double organ model.

METHODS

After stabilization With Krebs-Henseleit solution, isolated rat livers were either perfused or made ischemic for 2 hours. Aortic rings were stabilized, immersed in postischemic liver perfusates and their functions were tested. Some organs originated from donors fed with tungstate, whereas others had mannitol (0.25 g/kg) in the buffer.

RESULTS

Incubation of aortic rings with postischemic hepatic effluent resulted in protracted contraction. Spasm was slightly lesser when the livers were pretreated with tungstate or exposed to mannitol, but worse in pretreated rings. The return to basal tone was abrupt in all ischemia-reperfusion aortae. The response of the rings to phenylephrine under the influence of the ischemia-reperfusion hepatic effluent was deficient. Mannitol prevented most abnormal responses.

CONCLUSIONS

Aortal tone impairment can occur by direct influence of the ischemia-reperfusion liver. It cannot be attributed entirely to xanthine oxidase, but also to other hepatic-released factors.

Glutathione and ultrastructural changes in inflow occlusion of rat liver

BACKGROUND

Liver ischemia/reperfusion is frequently associated with organ injury to which reactive oxygen species contribute. The aim of our study was to evaluate cytosolic and mitochondrial glutathione levels and morphological changes in hepatocytes of rat liver in an experimental model of ischemia/reperfusion.

MATERIALS AND METHODS

The experimental procedure consisted of temporary interruption of blood flow to the left lateral and medial hepatic lobes for different lengths of time and, in some cases, subsequent reperfusion. Cytosolic and mitochondrial glutathione levels were evaluated and ultrastructural analysis was carried out for all samples.

RESULTS

Ischemic lobes showed ultrastructural changes in relationship with the increase in ischemia time. Total glutathione levels did not show variations in ischemic lobes and sham lobes with respect to control rats during ischemia only. Instead, during reperfusion, significant ultrastructural alterations of the hepatocytes and a significant depletion of glutatione in cytosolic and mitochondrial compartments were evident. The sham lobes also showed a significant glutathione decrement. Increased oxidized glutathione (GSSG) levels were found during ischemia both in ischemic lobes and in sham lobes. During reperfusion GSSG was found to a minor extent, in the cytosolic compartment. In mitochondria GSSG levels were also high during reperfusion.

CONCLUSIONS

We conclude that depletion of glutathione contributes to impaired liver after reperfusion following ischemia but depletion of glutathione alone does not induce changes in the morphology of the hepatocytes. Glutathione depletion and a greater quantity of GSSG, even in sham lobes, may indicate a metabolic alteration which spreads to compartments that are not involved in ischemia/reperfusion.

Cumulative damaging effect of liver hypoperfusion and cyclosporine a on the peribiliary capillary plexus: a study in an isolated dually perfused rat model

BACKGROUND

Cyclosporine (CsA) is an essential posttransplantation immunosuppressive drug. It may cause hepatotoxicity, mostly cholestasis, by unknown mechanism. CsA causes nephrotoxicity mainly by increased vascular resistance. We investigated the effects of CsA on the peribiliary capillary plexus, in an isolated, dually perfused (i.e., via the hepatic artery and the portal vein) rat liver preparation.

METHODS

After 30 min of stabilization with optimal flow (4 ml/min/g liver), four liver groups were perfused (control, n=5 each) and four groups were hypoperfused (n=5 each, 1 ml/min/g) for 120 min. This was followed by a 30-min optimal reperfusion phase, during which the controls and the hypoperfused groups were injected (60 sec) via the hepatic artery with CsA at high (3 mg/kg body weight in 1 ml) or low dose (0.03 mg/kg), cremophore (130 mg/kg), or saline (1 ml). A ninth group (n=5) underwent 2-hr ischemia and 30-min reperfusion to standardize liver damage. Dark nonradioactive microspheres (approximately 10 microm diameter) were injected via the hepatic artery 15 min after drug or saline injection.

RESULTS

Neither of the two CsA doses, nor cremophore controls, nor hypoperfusion alone caused entrapment of microspheres in the peribiliary circulation as assessed by light microscopy; perfusion pressures and resistances were also not altered. Significant arteriolar impaction and vasculature engorgement occurred in the hypoperfused plus high-dose CsA livers; hypoperfusion plus low-dose CsA or cremophore groups were minimally tainted. Vascular notable obstruction was associated with 15-40% increase in portal and arterial perfusion pressures and resistances, 50% decrease in oxygen extraction, and increase in lactate/pyruvate ratio, hepatocellular damage, and wet-to-dry weight ratio. Such findings were superior to those detected in the ischemic livers.

CONCLUSIONS

Acute single high-dose CsA injection, but not low-dose or cremophore, if combined with decreased flow, alters hepatic microcirculatory resistance. Possible correlations between such changes and clinical implications in organ transplantation are discussed.

Hemorrhage and renal ischemia-reperfusion upregulates the epidermal growth factor receptor in rabbit duodenum

To study the role of EGF-R in small intestinal adaptation to hemorrhage and I/R, anesthetized rabbits were implanted aseptically with arterial and venous catheters and bilateral renal artery Doppler flow probes and silastic occluders and allowed to recover. Rabbits were then randomly assigned to one of six groups: time control; hemorrhage (22.5 mL/kg) and 2.5 hours of renal occlusion (hemorrhage plus I/R); hemorrhage plus I/R and 2:1 LRS resuscitation; hemorrhage plus I/R and 3:1 LRS resuscitation; hemorrhage alone; or I/R alone. Rabbits were killed 48 hours after hemorrhage, and a section of duodenum was collected for analysis. Hemorrhage plus I/R induced a 2.5-fold increase in EGF-R tyrosine kinase activity compared with that found in the control group (P < .05), and this effect was not modified by either LRS resuscitation regimen. This increased activity was associated with similar Increases in EGF-R protein concentrations and approximately a 50% increase in EGF-R messenger (m)RNA levels compared with levels found in the control group. Further analysis of possible regulatory mechanisms for the increased EGF-R expression after hemorrhage plus I/R detected higher levels of EGF-R phosphorylation compared with those found in the control group but no significant increases in transforming growth factor-alpha mRNA levels. These data, coupled with a significant increase in duodenal thlobarbituric acid-reactive substance concentrations from rabbits in the hemorrhage plus I/R group, support the hypothesis that tyrosine kinase signal transduction pathways involving the EGF-R are activated in the small intestine after hemorrhage, renal I/R, or both, and this process may be mediated, at least in part, by oxidant stress.

Multiple organ dysfunction after remote circulatory arrest: common pathway of radical oxygen species?

OBJECTIVES

Cardiovascular, respiratory, and vascular dysfunction can follow trauma-induced no-flow-reflow states: hemorrhage, blunt trauma, or neurogenic shock. Liver ischemia-reperfusion (IR) induces remote lung damage by means of xanthine oxidase (XO) pro-oxidant activity. This damage was not proven in the heart, neither was the independent role of radical oxygen species (ROS) established in such cases. We investigated whether multiple organ dysfunction after a trauma-like IR is XO and ROS related and whether clinically used ROS scavengers could be beneficial.

METHODS

A controlled, randomized trial in which isolated rat livers, hearts, lungs, and aortic rings were perfused with Krebs-Henseleit solutions. After stabilization, livers were either perfused or made ischemic (2 hours). Then, pairs of liver plus heart, lung, or ring were reperfused in series (15 minutes), and then the second organ circulated alone for 45 minutes. Remote organ protection against the pro-oxidant hepatic-induced toxicity was evaluated by using allopurinol (1 mmol/L, heart), mannitol (0.25 g/kg, lung), or methylene blue (40 mg/kg, ring).

RESULTS

IR liver effluents typically contained high lactate dehydrogenase, XO, and uric acid concentrations compared with control organs. IR was associated with doubled lung peak inspiratory pressure and reduced static compliance. Myocardial velocity of contraction and relaxation decreased by one third of baseline, and rings contracted abnormally and responded inadequately to phenylephrine. Wet-weight to dry-weight ratios in the remote organs increased as well. Most remote reperfusion injuries were attenuated by the drugs.

CONCLUSION

Liver no-flow-reflow directly induces myocardial, pulmonary, and vascular dysfunction. These are likely mediated by XO and ROS. The tested drugs protected against these pro-oxidants, even in the presence of circulating XO.

Methylene blue prevents pulmonary injury after intestinal ischemia-reperfusion

OBJECTIVE

To investigate the effect of methylene blue, an inhibitor of oxygen radicals, on lung injury caused by reperfusion of ischemic tissue.

METHODS

Intestinal ischemia-reperfusion injury was induced in rats by clamping the superior mesenteric artery for 1 hour. Thereafter, the experimental group was administered 1% methylene blue intraperitoneally and the control group received saline. After 4 hours, pulmonary histopathologic features were assessed, and lung wet-weight to dry-weight ratios and tissue xanthine oxidase were determined.

RESULTS

The control group suffered from severe pulmonary parenchymal damage, compared with slight damage in the experimental group. The number of sequestered neutrophils was significantly higher in the control group (319 +/- 60 polymorphonuclear cells per 10 high-power fields) than in the methylene blue-treated group (91 +/- 8 polymorphonuclear cells per 10 high-power fields; p < 0.001). The wet-weight to dry-weight ratio was significantly increased in the saline-treated rats compared with the methylene blue-treated group (6.19 +/- 0.28 vs. 5.07 +/- 0.21; p < 0.001). Xanthine oxidase activity was similar in both groups.

CONCLUSION

Methylene blue attenuated lung injury after intestinal ischemia-reperfusion. Inhibition of oxygen free radicals may be the protective mechanism.