Propofol improves endothelial dysfunction and attenuates vascular superoxide production in septic rats

The grapes and wrath: using resveratrol to treat the pathophysiology of hemorrhagic shock

Resveratrol, a naturally occurring polyphenol found in grapes, has been shown to reduce oxidative stress and inflammation in a variety of conditions. Recently, resveratrol has been investigated as a potential adjunct to resuscitation therapy for hemorrhagic shock-a condition characterized by tissue hypoxia, mitochondrial dysfunction, and inflammation. Although standard resuscitation restores tissue perfusion, it can exacerbate oxidative stress and organ damage. In rodent models of severe hemorrhagic shock, resveratrol mitigates reperfusion injury, preserves organ function, and improves survival. While many of these benefits can be attributed to its ability to activate sirtuin 1, resveratrol interacts with many targets that are relevant to ischemia-reperfusion. Here, we explore the probable mechanisms, potential benefits, and possible problems associated with administering resveratrol as an adjunct during resuscitation of hemorrhagic shock.

Anti-Inflammatory and Organ-Protective Effects of Resveratrol in Trauma-Hemorrhagic Injury

Resveratrol, a natural polyphenolic compound of grape and red wine, owns potential anti-inflammatory effects, which results in the reduction of cytokines overproduction, the inhibition of neutrophil activity, and the alteration of adhesion molecules expression. Resveratrol also possesses antioxidant, anti-coagulation and anti-aging properties, and it may control of cell cycle and apoptosis. Resveratrol has been shown to reduce organ damage following traumatic and shock-like states. Such protective phenomenon is reported to be implicated in a variety of intracellular signaling pathways including the activation of estrogen receptor, the regulation of the sirtuin 1/nuclear factor-kappa B and mitogen-activated protein kinases/hemeoxygenase-1 pathway, and the mediation of proinflammatory cytokines and reactive oxygen species formation and reaction. In the recent studies, resveratrol attenuates hepatocyte injury and improves cardiac contractility due to reduction of proinflammatory mediator expression and ameliorates hypoxia-induced liver and kidney mitochondrial dysfunction following trauma and hemorrhagic injuries. Moreover, through anti-inflammatory effects and antioxidant properties, the resveratrol is believed to protect organ function in trauma-hemorrhagic injury. In this review, the organ-protective and anti-inflammatory effects of resveratrol in trauma-hemorrhagic injury will be discussed.

Organ-Protective Effects of Red Wine Extract, Resveratrol, in Oxidative Stress-Mediated Reperfusion Injury

Resveratrol, a polyphenol extracted from red wine, possesses potential antioxidative and anti-inflammatory effects, including the reduction of free radicals and proinflammatory mediators overproduction, the alteration of the expression of adhesion molecules, and the inhibition of neutrophil function. A growing body of evidence indicates that resveratrol plays an important role in reducing organ damage following ischemia- and hemorrhage-induced reperfusion injury. Such protective phenomenon is reported to be implicated in decreasing the formation and reaction of reactive oxygen species and pro-nflammatory cytokines, as well as the mediation of a variety of intracellular signaling pathways, including the nitric oxide synthase, nicotinamide adenine dinucleotide phosphate oxidase, deacetylase sirtuin 1, mitogen-activated protein kinase, peroxisome proliferator-activated receptor-gamma coactivator 1 alpha, hemeoxygenase-1, and estrogen receptor-related pathways. Reperfusion injury is a complex pathophysiological process that involves multiple factors and pathways. The resveratrol is an effective reactive oxygen species scavenger that exhibits an antioxidative property. In this review, the organ-protective effects of resveratrol in oxidative stress-related reperfusion injury will be discussed.

Shedding of the tumor necrosis factor (TNF) receptor from the surface of hepatocytes during sepsis limits inflammation through cGMP signaling

Proteolytic cleavage of the tumor necrosis factor (TNF) receptor (TNFR) from the cell surface contributes to anti-inflammatory responses and may be beneficial in reducing the excessive inflammation associated with multiple organ failure and mortality during sepsis. Using a clinically relevant mouse model of polymicrobial abdominal sepsis, we found that the production of inducible nitric oxide synthase (iNOS) in hepatocytes led to the cyclic guanosine monophosphate (cGMP)-dependent activation of the protease TACE (TNF-converting enzyme) and the shedding of TNFR. Furthermore, treating mice with a cGMP analog after the induction of sepsis increased TNFR shedding and decreased systemic inflammation. Similarly, increasing the abundance of cGMP with a clinically approved phosphodiesterase 5 inhibitor (sildenafil) also decreased markers of systemic inflammation, protected against organ injury, and increased circulating amounts of TNFR1 in mice with sepsis. We further confirmed that a similar iNOS-cGMP-TACE pathway was required for TNFR1 shedding by human hepatocytes in response to the bacterial product lipopolysaccharide. Our data suggest that increasing the bioavailability of cGMP might be beneficial in ameliorating the inflammation associated with sepsis.

Levosimendan attenuates multiple organ injury and improves survival in peritonitis-induced septic shock: studies in a rat model

INTRODUCTION

The aim of this study was to investigate the effects of levosimendan on rodent septic shock induced by cecal ligation and puncture (CLP).

METHODS

Three hours after peritonitis-induced sepsis, male Wistar rats were randomly assigned to receive an intravenous infusion of levosimendan (1.2 μg/kg/min for 10 min and then 0.3 μg/kg/min for 6 h) or an equivalent volume of saline and vehicle (5% dextrose) solution.

RESULTS

The levosimendan-treated CLP animals had significantly higher arterial pressure and lower biochemical indices of liver and kidney dysfunction compared to the CLP animals (P < 0.05). Plasma interleukin-1β, nitric oxide and organ superoxide levels in the levosimendan-treated CLP group were less than those in CLP rats treated with vehicle (P < 0.05). In addition, the inducible nitric oxide synthase (iNOS) in lung and caspase-3 expressions in spleen were significantly lower in the levosimendan-treated CLP group (P < 0.05). The administration of CLP rats with levosimendan was associated with significantly higher survival (61.9% vs. 40% at 18 h after CLP, P < 0.05). At postmortem examination, the histological changes and neutrophil filtration index in liver and lung were significantly attenuated in the levosimendan-treated CLP group (vs. CLP group, P < 0.05).

CONCLUSIONS

In this clinically relevant model of septic shock induced by fecal peritonitis, the administration of levosimendan had beneficial effects on haemodynamic variables, liver and kidney dysfunction, and metabolic acidosis. (1) Lower levels of interleukin-1β, nitric oxide and superoxide, (2) attenuation of iNOS and caspase-3 expressions, and (3) decreases of neutrophil infiltration by levosimendan in peritonitis-induced sepsis animals suggest that anti-inflammation and anti-apoptosis effects of levosimendan contribute to prolonged survival.

Propofol inhibits lipopolysaccharide-induced tumor necrosis factor-alpha expression and myocardial depression through decreasing the generation of superoxide anion in cardiomyocytes

TNF-α has been shown to be a major factor responsible for myocardial depression in sepsis. The aim of this study was to investigate the effect of an anesthetic, propofol, on TNF-α expression in cardiomyocytes treated with LPS both in vivo and in vitro. In cultured cardiomyocytes, compared with control group, propofol significantly reduced protein expression of gp91phox and phosphorylation of extracellular regulated protein kinases 1/2 (ERK1/2) and p38 MAPK, which associates with reduced TNF-α production. In in vivo mice studies, propofol significantly improved myocardial depression and increased survival rate of mice after LPS treatment or during endotoxemia, which associates with reduced myocardial TNF-α production, gp91phox, ERK1/2, and p38 MAPK. It is concluded that propofol abrogates LPS-induced TNF-α production and alleviates cardiac depression through gp91phox/ERK1/2 or p38 MAPK signal pathway. These findings have great clinical importance in the application of propofol for patients enduring sepsis.

Propofol inhibits superoxide production, elastase release, and chemotaxis in formyl peptide-activated human neutrophils by blocking formyl peptide receptor 1

Neutrophils play a critical role in acute and chronic inflammatory processes, including myocardial ischemia/reperfusion injury, sepsis, and adult respiratory distress syndrome. Binding of formyl peptide receptor 1 (FPR1) by N-formyl peptides can activate neutrophils and may represent a new therapeutic target in either sterile or septic inflammation. Propofol, a widely used i.v. anesthetic, has been shown to modulate immunoinflammatory responses. However, the mechanism of propofol remains to be established. In this study, we showed that propofol significantly reduced superoxide generation, elastase release, and chemotaxis in human neutrophils activated by fMLF. Propofol did not alter superoxide generation or elastase release in a cell-free system. Neither inhibitors of γ-aminobutyric acid receptors nor an inhibitor of protein kinase A reversed the inhibitory effects of propofol. In addition, propofol showed less inhibitory effects in non-FPR1-induced cell responses. The signaling pathways downstream from FPR1, involving calcium, AKT, and ERK1/2, were also competitively inhibited by propofol. These results show that propofol selectively and competitively inhibits the FPR1-induced human neutrophil activation. Consistent with the hypothesis, propofol inhibited the binding of N-formyl-Nle-Leu-Phe-Nle-Tyr-Lys-fluorescein, a fluorescent analog of fMLF, to FPR1 in human neutrophils, differentiated THP-1 cells, and FPR1-transfected human embryonic kidney-293 cells. To our knowledge, our results identify, for the first time, a novel anti-inflammatory mechanism of propofol by competitively blocking FPR1 in human neutrophils. Considering the importance of N-formyl peptides in inflammatory processes, our data indicate that propofol may have therapeutic potential to attenuate neutrophil-mediated inflammatory diseases by blocking FPR1.

Vitamin C in sepsis

Bacterial bloodstream infection causes septic syndromes that range from systemic inflammatory response syndrome (SIRS) and encephalopathy to severe sepsis and septic shock. Microvascular dysfunction, comprising impaired capillary blood flow and arteriolar responsiveness, precedes multiple organ failure. Vitamin C (ascorbate) levels are low in critically ill patients. The impact of ascorbate administered orally is moderate because of its limited bioavailability. However, intravenous injection of ascorbate raises plasma and tissue concentrations of the vitamin and may decrease morbidity. In animal models of polymicrobial sepsis, intravenous ascorbate injection restores microvascular function and increases survival. The protection of capillary blood flow and arteriolar responsiveness by ascorbate may be mediated by inhibition of oxidative stress, modulation of intracellular signaling pathways, and maintenance of homeostatic levels of nitric oxide. Ascorbate scavenges reactive oxygen species (ROS) and also inhibits the NADPH oxidase that synthesizes superoxide in microvascular endothelial cells. The resulting changes in redox-sensitive signaling pathways may diminish endothelial expression of inducible nitric oxide synthase (iNOS), tissue factor and adhesion molecules. Ascorbate also regulates nitric oxide concentration by releasing nitric oxide from adducts and by acting through tetrahydrobiopterin (BH4) to stimulate endothelial nitric oxide synthase (eNOS). Therefore, it may be possible to improve microvascular function in sepsis by using intravenous vitamin C as an adjunct therapy.

Inflammatory response in microvascular endothelium in sepsis: role of oxidants

Sepsis, as a severe systemic inflammatory response to bacterial infection, represents a major clinical problem. It is characterized by the excessive production of reactive oxygen species (ROS) both in the circulation and in the affected organs. The excessive generation of ROS inevitably leads to oxidative stress in the microvasculature and has been implicated as a causative event in a number of pathologies including sepsis. In this review, we focus on the role of oxidative and nitrosative stress during the early onset of sepsis. Changes in microvascular endothelial cells, the cell type that occurs in all organs, are discussed. The mechanisms underlying septic induction of oxidative and nitrosative stresses, the functional consequences of these stresses, and potential adjunct therapies for microvascular dysfunction in sepsis are identified.

Propofol mitigates systemic oxidative injury during experimental cardiopulmonary cerebral resuscitation

Effects of propofol, an intravenous anesthetic agent that exerts potent antioxidant properties, were investigated in an experimental model of cardiac arrest and cardiopulmonary resuscitation. An extended cardiac arrest with 15 randomized piglets was studied to assess the effect of propofol or its solvent intralipid as the control group. Oxidative stress (as measured by a major F(2)-isoprostane) and inflammation (a major metabolite of PGF(2α)) were evaluated in addition to the hemodynamic evaluation, protein S-100β and in situ tissue brain damage by immunochemistry at sacrifice after 3h of reperfusion following cardiac arrest and restoration of spontaneous circulation (ROSC). ROSC increased jugular bulb plasma levels of F(2)-isoprostane and PGF(2α) metabolite significantly more in controls than in the propofol-treated group. In situ tissue damage after ischemia-reperfusion was variable among the pigs at sacrifice, but tended to be greater in the control than the propofol-treated group. Propofol significantly reduced an ROSC-mediated oxidative stress in the brain.

Resveratrol prevents endothelial dysfunction and aortic superoxide production after trauma hemorrhage through estrogen receptor-dependent hemeoxygenase-1 pathway

OBJECTIVE

To determine whether resveratrol provides vasculoprotection in trauma-hemorrhaged animals and whether the effects are mediated via estrogen receptor-dependent hemeoxygenase-1.

DESIGN

Prospective, multiexperimental, randomized, controlled studies.

SETTING

University research laboratory.

SUBJECTS

Male Sprague-Dawley rats weighing 300-350 g.

INTERVENTIONS

Male Sprague-Dawley rats underwent trauma hemorrhage (mean arterial pressure 40 mm Hg for 90 min, then resuscitation). Resveratrol (30 mg/kg) with or without an estrogen receptor antagonist (ICI 182,780), a hemeoxygenase enzyme inhibitor (chromium-mesoporphyrin), or vehicle was injected during resuscitation. At 24 hrs after trauma hemorrhage with resuscitation or sham operation, the animals were euthanized for further evaluation.

MEASUREMENTS AND MAIN RESULTS

Acetylcholine-induced endothelium-dependent relaxation decreased, whereas nicotinamide adenine dinucleotide-stimulated superoxide radical production in the aorta and aortic p22phox, p47phox, gp91phox, NOX1, and NOX4 mRNA concentrations increased in trauma-hemorrhaged rats vs. sham rats. All altered parameters were normalized in resveratrol-treated trauma-hemorrhaged rats. Furthermore, there was a significant increase in hemeoxygenase-1 after trauma hemorrhage, and resveratrol treatment further increased hemeoxygenase-1 expression in trauma-hemorrhaged rats. However, administration of ICI 182,780 or chromium-mesoporphyrin abolished the resveratrol-induced prevention of shock-induced oxidative stress and endothelial damage. In the resveratrol-treated rats subjected to trauma hemorrhage, there were significant improvements in plasma aspartate aminotransferase and alanine aminotransferase levels, and mortality rate, and there was lesser damage in histology.

CONCLUSIONS

Resveratrol treatment prevented the overproduction of superoxide radical/NADPH oxidase expression and restored the trauma-hemorrhage-impaired endothelium-dependent relaxation via estrogen receptor-dependent stimulation of hemeoxygenase-1 expression.

Gender-specific effects of caloric restriction on the balance of vascular nitric oxide and superoxide radical

AIMS

Caloric restriction (CR) and female gender attenuate oxidative damage and improve vascular endothelium-dependent relaxation (EDR). Multiple mechanisms that ameliorate vascular O(2)(*-) could enhance the NO(*)/O(2)(*-) balance and thus improve EDR. The aim of this study is to compare the effects of short-term (2 weeks) CR and gender on molecular mechanisms involved in NO(*)/O(2)(*-) balance and EDR.

METHODS AND RESULTS

Wistar rats (8 weeks old) of both genders were fed ad libitum (control) or were subjected to CR (60% of food intake of controls) for 2 weeks. Plasma levels of NO(*), insulin, and ghrelin, EDR, vascular NO(*) and O(2)(*-) production, as well as endothelial NO(*) synthase (eNOS) and NADPH oxidase (Nox) expression were examined and analysed. CR improved EDR and vascular NO(*) levels and ameliorated NADPH-sensitive O(2)(*-) production in male rats more than in females. Both CR and female gender reduced mRNA expression of Nox1 and Nox p22phox (p22phox); however, CR reduced Nox4 and p47phox only in males. Protein expression studies showed that CR enhanced eNOS and reduced Nox4 only in males.

CONCLUSION

Short-term CR improved the NO(*)/O(2)(*-) balance by lowering vascular O(2)(*-) production through decreased expression of Nox in males, thus enhancing bioactive NO(*) levels and EDR. In this regard, CR shifted the state of vascular NO(*)/O(2)(*-) balance in males to a state similar to that in females.

Intensive Care Unit-acquired infection as a side effect of sedation

Introduction

Sedative and analgesic medications are routinely used in mechanically ventilated patients. The aim of this review is to discus epidemiologic data that suggest a relationship between infection and sedation, to review available data for the potential causes and pathophysiology of this relationship, and to identify potential preventive measures.

Methods

Data for this review were identified through searches of PubMed, and from bibliographies of relevant articles.

Results

Several epidemiologic studies suggested a link between sedation and ICU-acquired infection. Prolongation of exposure to risk factors for infection, microaspiration, gastrointestinal motility disturbances, microcirculatory effects are main mechanisms by which sedation may favour infection in critically ill patients. Furthermore, experimental evidence coming from studies both in humans and animals suggest that sedatives and analgesics present immunomodulatory properties that might alter the immunologic response to exogenous stimuli. Clinical studies comparing different sedative agents do not provide evidence to recommend the use of a particular agent to reduce ICU-acquired infection rate. However, sedation strategies aiming to reduce the duration of mechanical ventilation, such as daily interruption of sedatives or nursing-implementing sedation protocol, should be promoted. In addition, the use of short acting opioids, propofol, and dexmedetomidine is associated with shorter duration of mechanical ventilation and ICU stay, and might be helpful in reducing ICU-acquired infection rates.

Conclusions

Prolongation of exposure to risk factors for infection, microaspiration, gastrointestinal motility disturbances, microcirculatory effects, and immunomodulatory effects are main mechanisms by which sedation may favour infection in critically ill patients. Future studies should compare the effect of different sedative agents, and the impact of progressive opioid discontinuation compared with abrupt discontinuation on ICU-acquired infection rates.

The effects of propofol on vascular function in mesenteric arteries of the aging rat

Hypotension following administration of propofol, an anesthetic agent, is strongly predicted by advanced age and is partly due to direct vasodilation. We hypothesized that propofol increases nitric oxide (NO)-mediated vasodilation by enhancing its bioavailability in the aged adult vasculature, leading to greater vasodilation than in the young adult. Small mesenteric arteries from rats aged 13–15 versus 3 to 4 mo were compared in this study. Reactivity to propofol (1–100 μM) alone and with the addition of acetylcholine (ACh; 0.1–10 μM) in endothelial-intact and dunuded arteries following phenylephrine constriction was assessed using myography. NG-nitro-l-arginine methyl ester (l-NAME) and meclofenamate (Meclo) were used to inhibit NO and prostaglandin synthesis, respectively. Superoxide dismutase (SOD) and catalase were used as antioxidants during ACh relaxation and were compared with propofol in aging arteries. Propofol alone induced greater relaxation in 1) endothelial-intact compared with denuded arteries and 2) aged compared with young arteries, which were inhibited by l-NAME. ACh-induced relaxation was greater in young compared with aged control arteries; however, propofol pretreatment increased this relaxation in aged but not in young arteries. Additionally, propofol inhibited ACh-induced relaxation in arteries treated with l-NAME + Meclo [relaxation attributed to endothelium-derived hyperpolarizing factor (EDHF)]. Pretreatment with SOD and catalase increased relaxation to ACh in aged arteries similar to propofol. In conclusion, propofol causes relaxation in small mesenteric arteries in an endothelial-dependent and independent manner and increases ACh-induced relaxation in aged arteries. Interestingly, propofol inhibits EDHF-mediated relaxation but increases availability of NO, which leads to overall vascular relaxation.

Effects of chronic 4-n-nonylphenol treatment on aortic vasoconstriction and vasorelaxation in rats

4-Nonylphenol (para-nonylphenol, 4-NP), metabolites including linear and branched isoforms of nonylphenol (n-NP and t-NP, respectively), has been considered an endocrine disrupting substance resulting in reproductive dysfunction and increasing reactive oxygen species production in testis, liver, kidney, and brain. However, to date, whether vasculature is susceptible to NP exposure remains to be unclear. In this study, we have investigated the effects of chronic in vivo 4-n-NP exposure on vasoconstriction and vasorelaxation in male rats. After a 20-week 4-n-NP treatment orally at the dosage of 10 and 50 muM in the drinking water, phenylephrine- and potassium chloride-induced concentration-dependent responsiveness assessed by wire myograph were both significantly higher in aorta isolated from 4-n-NP-treated rats compared with control rats, but acetylcholine-induced vasorelaxation was similar between these two groups. In addition, systemic oxidative stress and vascular, but not intestinal, oxidant enzyme activities assessed by lucigenin-amplified chemiluminescence were all markedly higher in 4-n-NP-treated rats. In conclusion, our results suggested that chronic in vivo 4-n-NP exposure augments vascular contractile responsiveness through enhanced vascular oxidant enzyme activity.

Differential protection against oxidative stress and nitric oxide overproduction in cardiovascular and pulmonary systems by propofol during endotoxemia

Background

Both overproduction of nitric oxide (NO) and oxidative injury of cardiovascular and pulmonary systems contribute to fatal cardiovascular depression during endotoxemia. We investigated in the present study the relative contribution of oxidative stress and NO to cardiovascular depression during different stages of endotoxemia, and delineated their roles in cardiovascular protective effects of a commonly used anesthetic propofol during endotoxemia.

Methods

Experimental endotoxemia was induced by systemic injection of E. coli lipopolysaccharide (LPS, 15 mg/kg) to Sprague-Dawley rats that were maintained under propofol (15 or 30 mg/kg/h, i.v.) anesthesia. Mean systemic arterial pressure (MSAP) and heart rate (HR) were monitored for 6 h after the endotoxin. Tissue level of NO was measured by chemical reduction-linked chemiluminescence and oxidative burst activity was determined using dihydroethidium method. Expression of NO synthase (NOS) was determined by immunoblotting. The Scheffé multiple range test was used for post hoc statistical analysis.

Results

Systemic injection of LPS (15 mg/kg) induced biphasic decreases in MSAP and HR. In the heart, lung and aorta, an abrupt increase in lipid peroxidation, our experimental index of oxidative tissue injury, was detected in early stage and sustained during late stage cardiovascular depression. LPS injection, on the other hand, induced a gradual increase in tissue nitrite and nitrate levels in the same organs that peaked during late stage endotoxemia. Propofol infusion (15 or 30 mg/kg/h, i.v.) significantly attenuated lipid peroxidation in the heart, lung and aorta during early and late stage endotoxemia. High dose (30 mg/kg/h, i.v.) propofol also reversed the LPS-induced inducible NO synthase (iNOS) upregulation and NO production in the aorta, alongside a significant amelioration of late stage cardiovascular depression and increase in survival time during endotoxemia.

Conclusion

Together these results suggest that oxidative injury and NO may play a differential role in LPS-induced cardiovascular depression. Oxidative tissue injury is associated with both early and late stage; whereas NO is engaged primarily in late stage cardiovascular depression. Moreover, propofol anesthesia may protect against fatal cardiovascular depression during endotoxemia by attenuating the late stage NO surge in the aorta, possibly via inhibition of iNOS upregulation by the endotoxin.

Mechanism of action of vitamin C in sepsis: ascorbate modulates redox signaling in endothelium

Circulating levels of vitamin C (ascorbate) are low in patients with sepsis. Parenteral administration of ascorbate raises plasma and tissue concentrations of the vitamin and may decrease morbidity. In animal models of sepsis, intravenous ascorbate injection increases survival and protects several microvascular functions, namely, capillary blood flow, microvascular permeability barrier, and arteriolar responsiveness to vasoconstrictors and vasodilators. The effects of parenteral ascorbate on microvascular function are both rapid and persistent. Ascorbate quickly accumulates in microvascular endothelial cells, scavenges reactive oxygen species, and acts through tetrahydrobiopterin to stimulate nitric oxide production by endothelial nitric oxide synthase. A major reason for the long duration of the improvement in microvascular function is that cells retain high levels of ascorbate, which alter redox-sensitive signaling pathways to diminish septic induction of NADPH oxidase and inducible nitric oxide synthase. These observations are consistent with the hypothesis that microvascular function in sepsis may be improved by parenteral administration of ascorbate as an adjuvant therapy.

Combined effects of propofol and dexamethasone on rats with endotoxemia

OBJECTIVE

To clarify the effect of combined treatment with propofol and dexamethasone on hemodynamics, organ injury, and survival rate in rats with endotoxemia.

DESIGN

Randomized, prospective animal experiment.

SETTING

Academic research laboratory.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

Rats were divided into five groups: a control group, a group of conscious rats infused with Escherichia coli lipopolysaccharide, two groups of lipopolysaccharide rats treated with either propofol or dexamethasone, and a group of lipopolysaccharide rats with combined treatment of propofol and dexamethasone.

MEASUREMENTS AND MAIN RESULTS

All hemodynamic and biochemical variables were measured during the 6-hr observation. Propofol plus dexamethasone attenuated hypotension and delayed hypoglycemia and metabolic acidosis caused by coadministration of E. coli lipopolysaccharide. In addition, propofol plus dexamethasone attenuated the lipopolysaccharide-induced multiple organ dysfunctions, such as lung, liver, and kidney. The increases in serum tumor necrosis factor-alpha, tissue nitric oxide, and superoxide anion levels were attenuated by propofol plus dexamethasone in lipopolysaccharide rats. Microscopic findings confirmed that propofol plus dexamethasone attenuated the substantial swelling and cell infiltration in lung and kidney caused by endotoxin. The 22-hr survival rate after endotoxin injection was markedly increased in lipopolysaccharide rats with combined treatment compared with the lipopolysaccharide rats (80% vs. 0%).

CONCLUSIONS

The combined treatment with propofol plus dexamethasone reduced mortality rate and attenuated organ injury in conscious rats treated with lipopolysaccharide. These protective effects may be associated with their anti-inflammatory capacity and antioxidant activity.

Protective effects of propofol on acute lung injury induced by oleic acid in conscious rats

OBJECTIVES

Oleic acid has been used to induce acute lung injury (ALI) in animals. In patients with acute respiratory distress syndrome (ARDS), the blood level of oleic acid was increased. The mechanism and therapeutic regimen of ARDS and oleic acid-induced ALI remain undefined. In the present study, we investigated the oleic acid-induced changes in lung variables for the measure of ALI, inflammatory mediators, and neutrophil-derived substances. We evaluated the effects of pretreatment and posttreatment with propofol.

DESIGN

Randomized, controlled animal study.

SETTING

University research laboratory.

SUBJECTS

Fifty adult male Sprague-Dawley rats weighing 250-300 g.

INTERVENTIONS

We employed a conscious and unrestrained rat model. Oleic acid at a dose of 100 mg/kg was administered intravenously. Propofol (30 mg/kg) was given by intravenous infusion (6 mg/kg/min for 5 mins) 30 mins before (pretreatment) and 30 mins after (posttreatment) oleic acid.

MEASUREMENTS AND MAIN RESULTS

We monitored the arterial pressure, heart rate, and blood gas. The lung weight changes, exhaled nitric oxide, protein concentration in bronchoalveolar lavage, and Evans blue content in lung tissue were determined. The plasma nitrate/nitrite, methylguanidine, cytokines (tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, and interleukin-10), neutrophil elastase, myeloperoxidase, malondialdehyde, and sodium- and potassium-activated adenosine triphosphatase (Na+-K+-ATPase) were detected. Histopathological examination of the lung was performed. Oleic acid caused systemic hypotension and severe ALI as evidenced by the increases in the extent of ALI, impairment of pulmonary functions (blood gas variables), and lung pathology. In addition, oleic acid significantly increased inflammatory mediators and neutrophil-derived factors but depressed Na+-K+-ATPase. The inducible nitric oxide synthase was up-regulated. Pre- or posttreatment with propofol was capable of reversing the oleic acid-induced changes and attenuating the extent of ALI.

CONCLUSIONS

Oleic acid resulted in sepsis-like responses including ALI, inflammatory reaction, and increased neutrophil-derived factors. It depressed the Na+-K+-ATPase activity but up-regulated inducible nitric oxide synthase. Treatment with propofol abrogated or reversed the oleic acid-induced changes.

Propofol attenuates intestinal mucosa injury induced by intestinal ischemia-reperfusion in the rat

PURPOSE

We investigated whether propofol at a sedative dose can prevent intestinal mucosa ischemia/reperfusion (I/R) injury, and if propofol can attenuate oxidative stress and increases in nitric oxide (NO) and endothelin-1 (ET-1) release that may occur during intestinal I/R injury.

METHODS

Rats were randomly allocated into one of five groups (n=10 each): (i) sham control; (ii) injury (one hour superior mesenteric artery occlusion followed by three hours reperfusion); (iii) propofol pre-treatment, with propofol given 30 min before inducing intestinal ischemia; (iv) simultaneous propofol treatment, with propofol given 30 min before intestinal reperfusion was started; (v) propofol post-treatment, with propofol given 30 min after intestinal reperfusion was initiated. In the treatment groups, propofol 50 mg x kg(-1) was administrated intraperitoneally. Animals in the control and untreated injury groups received equal volumes of intralipid (the vehicle solution of propofol) intraperitoneally. Intestinal mucosa histology was analyzed by Chiu's scoring assessment. Levels of lactic acid (LD), NO, ET-1, lipid peroxidation product malondialdehyde (MDA) and superoxide dismutase (SOD) activity in intestinal mucosa were determined.

RESULTS

Histological results showed severe damage in the intestinal mucosa of the injury group accompanied by increases in MDA, NO and ET-1 and a decrease in SOD activity. Propofol treatments, especially pre-treatment, significantly reduced Chiu's scores and levels of MDA, NO, ET-1 and LD, while restoring SOD activity.

CONCLUSION

These findings indicate that propofol attenuates intestinal I/R-induced mucosal injury in an animal model. The response may be attributable to propofol's antioxidant properties, and the effects of inhibiting over-production of NO and in decreasing ET-1 levels.

Halothane induces oxidative stress and NF-kappaB activation in rat liver: protective effect of propofol

We investigated the effects of propofol on markers of oxidative stress, nuclear factor kappa B (NF-kappaB) activation and inducible nitric oxide synthase (iNOS) expression in liver of rats treated with halothane under hypoxic conditions. Male Wistar rats received halothane 1%/oxygen 14%, oxygen 14%/propofol 60 mg kg(-1) i.p., or halothane 1%/oxygen 14%/propofol 60 mg kg(-1) i.p. Morphological examination showed complete loss of architecture with massive necrosis of parenchyma in the halothane group, while only minor histological abnormalities were observed in rats receiving halothane plus propofol. The cytosolic concentration of TBARS and the hydroperoxide-initiated chemiluminescence increased significantly in the liver of animals from the halothane group (+62% and +40% versus controls, respectively), and this increase was abolished by propofol administration. Halothane induced a marked activation of NF-kappaB (+180%), and resulted in a significant decrease of the nonphosphorylated form of the inhibitor IkappaBalpha (-53%), while phosphorylated IkappaBalpha protein level was markedly increased (+146%). Propofol administration lowered these effects to +30% (NF-kappaB), -26% (nonphosphorylated IkappaBalpha), and +56% (phosphorylated IkappaBalpha). The increase of iNOS protein level (+59%) induced by halothane was significantly reduced to +22% by additional administration of propofol. Results obtained show that administration of propofol inhibits oxidative stress, NF-kappaB nuclear traslocation and iNOS overexpression in liver of rats receiving halothane. Propofol treatment, by inhibiting the NF-kappaB signal transduction pathway, might block the production of noxious mediators involved in the development of halothane-induced injury.