Endotoxic Shock In Rats Research Articles

Acute renal injury induced by endotoxic shock in rats is alleviated via PI3K/Nrf2 pathway.

To explore the effect of PI3K/Nrf2 pathway on acute kidney injury (AKI) induced by endotoxic shock in rats by construction of the endotoxic shock rat model. A total of 30 Sprague Dawley (SD) rats were randomly assigned into three group, namely the control group (group C), endotoxic shock model group (group L) and wortmannin + endotoxic shock model group (group WL), with 10 rats in each group. Pathological lesions in renal tissues were evaluated by histological score of kidney (HSK). Biochemical indicators including blood urine nitrogen (BUN), creatinine (Cr) and urinary α1-microglobulin (α1-MG) in renal tissues were accessed. Activities of superoxide dismutase (SOD) and malondialdehyde (MDA) were detected by relative commercial kits. Expression levels of Nrf2, Heme oxygenase 1 (HO-1) and Akt in renal tissues were determined by Western blot and quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), respectively. HSK, levels of BUN, Cr and α1-MG and activities of SOD and MDA were significantly increased in group L comparing to those in group C (p<0.05). The above-mentioned indicators were also remarkably higher in group WL than those of group L (p<0.05). There were significant differences in expression levels of Nrf2, HO-1 and Akt between group L and group WL (p<0.05). In particular, lower mRNA levels of Nrf2 and HO-1, as well as protein levels of p-Akt, Nrf2 and HO-1 were observed in group WL compared with those in group L (p<0.05). The present study showed that AKI induced by endotoxic shock in rats was regulated through PI3K/Nrf2 pathway. HO-1 acts as the effector protein, might serve as an essential factor in protecting AKI induced by endotoxic shock.

The therapeutic effects of cholecystokinin octapeptide on rat liver and kidney microcirculation disorder in endotoxic shock

Objectives: Our previous studies demonstrated that pretreatment with cholecystokinin octapeptide (CCK-8) could alleviate endothelial cell injury and reverse abnormal vascular reactivity as well as reduce LPS-induced inflammation cascades, which suggested that CCK-8 plays a potential role in anti-endotoxic shock. The present study aimed to determine the therapeutic effects of CCK-8 on rat liver and kidney microcirculatory perfusion disorder under endotoxic shock (ES) conditions.Materials and Methods: Sprague-Dawley rats were induced to lethal endotoxic shock by an injection of LPS. CCK-8 was administered 30 min after LPS injection. Either a specific CCK-1R antagonist or CCK-2R antagonist was injected before CCK-8 treatment. The mean arterial pressure (MAP), liver and kidney microcirculatory perfusion, and heart rate (HR) were recorded with a multi-channel data acquisition system. The serum concentrations of alanine aminotransferase (ALT) and creatinine (Cr) were measured, and the histopathological changes in the liver and kidney were also observed.Results: Administration of CCK-8 significantly delayed the LPS-induced decreases in not only the liver and kidney microcirculation perfusion but also the HR. The pathology changes induced by LPS in the liver and kidney tissues were significantly mitigated in the LPS + CCK-8 group. The levels of ALT and Cr in the serum of the LPS + CCK-8 group were obviously lower than those in the LPS group. In addition, the specific antagonist at the CCK-2 receptor (CCK-2R) abrogated the action of CCK-8 significantly.Conclusions: These results indicated that CCK-8 has potential therapeutic effects on microcirculation failure in an ES rat model via the CCK-2 receptor.

Effect of extracellular signal-regulated kinases signaling pathway on the expression of heme oxygenase-1 in the lung during endotoxic shock in rats

Objective To investigate the effects of extracellular signal-regulated kinases (ERK1/2) signaling pathway on the expression of heme oxygenase-1 (HO-1) in acute lung injury of endotoxic shock induced by lipopolysaccharide (LPS) in rats.Methods Forty-eight pathogen-free male SD rats weighing 180 g-200 g were randomly divided into 4 groups (n=12 each):sham operation group (group S),endotoxic shock group (group SS),endotoxic shock and PD98059 group (group SE) and PD98059 group (group E).Rats in group S and group SS were administrated with DMSO 0.1 ml intravenously.Rats in Group SE and group E were injected with the inhibitor of ERK1/2 (PD98059) in 0.1 ml DMSO intravenously.30 min later,rats in Group S and group E received 0.5 ml normal saline intravenously while rats in group SS and group SE received LPS 10 mg/kg in 0.5 ml normal saline intravenously.The invasive arterial pressure was monitored,if there was an initial 25％ decrease in mean arterial pressure,then the model can be put to use.The lung injury degree was judged by microscopic examination,moisture content,malondialdehyde (MDA) content and superoxide dismutase (SOD) activity.The ERK1/2 protein,p-ERK1/2 protein and HO-1 protein were measured by Western blot.HO-1 mRNA level were measured by RT-PCR.Results The grade of the pathology (4.5 ±2.1),MDA content (3.12±1.30) nmol/mg,moisture content(81±6)％ in group SS were significantly higher than that in group S (2.0±1.0),(78±5)％,(1.79±0.12) nmol/mgand group E (2.1±1.1),(77±4)％,(1.83±-0.20) nmol/mg,(P＜0.05).But significantly lower than that in group SE(6.4±1.3),(87±5)％,(4.62±0.92) nmol/mg (P＜0.05).The SOD activity in group SS (20.2±2.4) NU/mg were significantly lower than that in group S (30.9± 2.9) NU/mgand group E (32.2±1.2) NU/mg(P＜0.05),but significantly higher than that in group SE(14.9±3.2) NU/mg(P＜0.05).ERK1/2 protein (0.43±0.09) and p-ERK1/2 protein (1.46 ±0.22),HO-1mRNA (1.834± 0.023) and HO-1 protein (1.17± 0.25) in group SS were significantly higher than that in group S,group SE and group E (P＜0.05).And there were no significant difference in group S and group P among all the indexes (P＞0.05).Conclusions Using the inhibitor of ERK1/2 signaling pathway in endotoxic shock rats worsened lung injury,and its mechanism may be related to decreased HO-1 expression by inhibition of ERK1/2 signaling pathway. Key words: Extracellular signal-regulated kinases; Endotoxic shock; Lung; Heme oxygenase-1

Effects of low power laser radiation of blue, green and red ranges on free radical processes in rat blood in endotoxic shock

This study was performed to investigate the effects of low power laser radiation in blue (441.2 nm), green (532.5 nm) and red (632.8 nm) wavelength ranges on free radical processes in experimental endotoxic shock in rats. The experimental model was produced by intraperitoneal injection of lipopolysacharide B (25 mg/kg) (LPS). The following parameters were assayed in the study: the chemiluminescent assay (to evaluate the free radical production by blood leukocytes), nitro blue tetrazolium assay (to monitor the superoxide dismutase activity of plasma) and cis-parinaric acid fluorescence (to estimate the intensity of lipid peroxidation in erythrocyte membranes). It was found that the low power laser radiation significantly influenced all investigated processes, in animals both treated and untreated without LPS injection. The most pronounced effects were observed in all groups of animals subjected to the low power laser radiation: at the dose of 0.75 J/cm2 green laser was most effective and at the dose of 1.5 J/cm2 green and red lasers provided maximal effects. The mechanisms of the observed phenomena are discussed.

Effects of lipoic acid on spleen oxidative stress after LPS administration

BackgroundBacterial endotoxin (lipopolysaccharide – LPS) is a strong modulator of the immune system that plays a crucial role in the pathogenesis of endotoxic shock. The aim of the study was to investigate the effects of lipoic acid (LA) on oxidative stress markers in spleen homogenates obtained from LPS-induced endotoxic shock rats. MethodsThe animals were treated with saline or lipoic acid (LA) (60 or 100mg/kg b.w. iv) 30min before or 30min after LPS administration (30mg/kg b.w. iv). Five hours after LPS, LA or saline administration, the animals were euthanized and their spleens were isolated for measurements. ResultsThe LPS-treated animals developed oxidative stress, indicated by a significant increase in thiobarbituric acid-reactive substances (TBARS) and hydrogen peroxide (H2O2) concentrations (p<0.001) as well as an insignificant decrease in the level of sulfhydryl groups (-SH groups) and the glutathione redox ratio [reduced glutathione (GSH) to oxidized glutathione (GSSG) ratio] (p<0.02) as compared with control group. Treatment with LA (60 or 100mg/kg) before or after LPS administration resulted in an increase in -SH group content (p<0.01) and a decrease in TBARS and H2O2 concentration in the spleen as compared with LPS group (p<0.001). LA (60 or 100mg/kg) before LPS administration decreased the level of GSSG (p<0.05) and increased the level of GSH in spleen homogenates (p<0.05), resulting in an increase in the GSH/GSSG ratio compared with the LPS group (p<0.01). It also improved the LPS-induced increase in the spleen weight (SW) to body weight (BW) ratio (p<0.001 vs. control). ConclusionThe present results have shown that LAis endowed with antioxidant properties that are protective in the spleen against the deleterious actions of Gram-negative bacterial endotoxin.

Effects of laser and LED radiation on mitochondrial respiration in experimental endotoxic shock

Effects of low-level laser therapy (442 and 532 nm) and LED radiation (650 nm) on mitochondrial respiration in experimental endotoxic shock have been studied. A model of experimental endotoxic shock in rats was obtained by intraperitoneal injection of lipopolysaccharide B. It was found that low-level laser therapy and LED radiation dramatically affected the rate of mitochondrial respiration in third and fourth states both in LPS-treated animals and in control experiments. The maximal increase of the mitochondrial respiration rate (of about 40 %) in LPS-treated animals was observed when blue laser was applied at the dose of 6 J/cm(2). Measurements of inner mitochondrial membrane surface potential with fluorescence probe JC-1 in LPS-treated rats showed in approximately 10 % decrease of potential in LPS-treated animals compared to control.

The effect of low power laser radiation of blue, green, and red ranges on free radical processes in blood of rats with experimental endotoxic shock

This study was performed to investigate the effects of low power laser radiation in blue (441.2 nm), green (532.5 nm) and red (632.8 nm) wavelength ranges on free radical processes in experimental endotoxic shock in rats. The experimental model was induced by intraperitoneal injection of lipopolysaccharide B (25 mg/kg) (LPS). Functional activity of blood leukocytes was evaluated by the method of luminol-dependent chemiluminescence, plasma superoxide dismutase activity was determined by the nitro blue tetrazolium assay, intensity of lipid peroxidation in erythrocyte membranes was estimated by cis-parinaric acid fluorescence. It was found that the low power laser radiation significantly influenced all investigated processes, in LPS-treated and control animals. The most pronounced effects were observed in all groups of LPS-treated animals, in which the laser radiation increased all investigated parameters. At the radiation dose 0.75 J/cm2 green laser was the most effective, while at the dose of 1.5 J/cm2 both green and red lasers produced potent effects. Possible mechanisms of the observed phenomena are discussed.

A novel DDAH-1 inhibitor improved sepsis-induced impairment in vasoreactivity to noradrenaline in a rat endotoxaemia model

In septic shock, iNOS activation and nitric oxide (NO) overproduction contribute to vascular hyporeactivity to adrenergic vasopressors. The consequent hypotension often necessitates high doses of catecholamine administration. However, this may lead to detrimental effects on tissue perfusion, immune function and myocardial function. Asymmetric dimethlyarginine (ADMA), an endogenous inhibitor of NO synthase, is extensively metabolised by dimethylarginine dimethylaminohydrolase (DDAH). Competitive inhibition of the DDAH-1 isoform should thus reverse hypotension but, as this isoform is absent in immune cells, it should not compromise the immune effects of NO. Hence, we investigated whether L257, a novel DDAH-1 inhibitor, could spare norepinephrine dosing in a rat endotoxic shock model.

Protective effects of endothelin-A receptor antagonist BQ123 against LPS-induced oxidative stress in lungs

The aim of this study was to assess whether endothelin-A receptor (ETA-R) blocker, BQ123, influences lung edema, lipid peroxidation (TBARS), hydrogen peroxide (H2O2), TNF-α concentration or the glutathione redox system in the lung homogenates obtained from LPS-induced endotoxic shock rats. The study was performed on male Wistar rats (n=6 per group) divided into groups: (1) saline, (2) LPS (15mg/kg)-saline, (3) BQ123 (0.5mg/kg)-LPS, (4) BQ123 (1mg/kg)-LPS. The ETA-R antagonist was injected intravenously 30min before LPS administration. Five hours after saline or LPS administration, animals were sacrificed and lungs were isolated for indices of lung edema, oxidative stress and TNF-α concentration. Injection of LPS alone resulted in lung edema development and a marked increase in TNF-α (p<0.02), TBARS (p<0.02), and H2O2 (p<0.01) concentrations as well as a depletion of total glutathione (p<0.01). Administration of BQ123 (1mg/kg), before LPS challenge, led to a significant reduction in TNF-α and H2O2 concentrations (p<0.05) and elevation of both total glutathione and the GSH/GSSG ratio (p<0.05). However, it did not prevent LPS-induced TBARS increase and lung edema formation. Interestingly, a lower dose of BQ123 was much more effective in decreasing H2O2, TBARS, as well as TNF-α levels (p<0.02, p<0.05, p<0.05, respectively). That dose was also effective in prevention of lung edema development (p<0.01). Taken together, the obtained results indicate that BQ123 is highly effective in decreasing LPS-induced oxidative stress in lungs. Moreover, the dose of 0.5mg/kg of the antagonist showed to be more effective in decreasing free radical generation and lung edema in endotoxemic rats.

Variation analysis of early gene expression profiles of lung in rats with endotoxic shock

Objective To observe the difference of gene expression profiles of lung in rats before and after endotoxic shock （ES）. Methods A total of 20 male Wistar rats were randomly divided into control group and lipopolysaceharide （LPS） group （ 10 rats per group）. The LPS rat model was made by injecting LPS into tail vein. Six hours after ES, partial pressure of oxygen in the arterial blood （ PaO2 ）was measured. Gene expression profiles of the lung in each group were detected by rats oligo gene chip Affymetrix RAT 230A. The expression level of five genes was verified via semi-quantitative RT-PCR. The data were analyzed in combination with type of differential gene and character of ES. Results Compared with control group, PaO2 in LPS group was decreased more significantly （P 〈0.05）. Among 15 650 probes detected, 158 genes showed differential expression in ES group in comparison with control group. The expression level of 117 genes was up-regulated while that of 34 genes down-regulated significantly. According to their biological function, differentially expressed genes were classified as inflammation genes, material transporter genes, transcription regulator genes, signal transduction genes, stress response genes, metabolic genes, apoptosis genes and cell adhesion genes. The results of Semi-quantitative RT-PCR of five genes were consistent with those of the microarray examination. Conclusion The expression of many genes of the lung may change in ES rats, especially the inflammatory genes. Key words: Lung ; Endotoxin ; DNA chip ; Gene expression

Clucocorticoid receptor expression in the lung tissue in endotoxic shock rat

Objective To investigate the effects of vasoactive intestinal peptide(VIP)on TLR 2,4 mRNA expressions in the lung tissue in endotoxic shock rat induced by LPS rat.Method Fifty six SD rats were far.rely (random number)divided into 4 groups,including LPS shock group(n=16),LPS+VIP group(n=16),LPS+V1P+GC group(n=16),and control group(n=8).LPS shock model was made by intravenously injecting with LPS(10 mg/kg);rats in the LPS+VIP group were intravenously injected with VIP after LPS;rats in the LPS+VIP+GC group were injected with VIP and methylprednisolone together with LPS;rats in the control group were given with normal saune.The rats were sacrificed at 6 h,24 h after injected.The lung tissues were collected.Pathological changes of the lungs were observed under hght microscope and electron microscope.The GR mRNA expressions were assessed by RT-PCR in the lung tissues.Results(1)Lung histopathology:necrotic abscission cells increased in alveolar space,inflammatory cells infiltration and lung interstitial edema appeared in LPS shock group.However,pathological changes in LPS+VIP group and LPS+VIP+GC group were milder than those in LPS shock group.(2)After 6 hours LPS injection,the GR mRNA expression in LPS group and LPS+VIP group were significantly lower as compared with those of the control group(P＜0.05),the GR mRNA expressions of LPS+VIP+GC group at 6 h and 24 h were significantly higher than those of the other groups(P＜0.05).Condusions Expression of GR mRNA decreases in rats with LPS-induced lung injury.VIP+GC can reduce lung injury,which may have correlation with up-regulation of GR mRNA expression. Key words: Ghcocorticoid; GR mRNA; Vasoactive intestinal peptide; LPS; Shock; Inflammation; Lung injury; Rat

Synergism in survival to endotoxic shock in rats given microencapsulated CNI-1493 and antisense oligomers to NF-κB

The synthesis of TNF may be inhibited at the transcriptional level by antisense to either TNF or NF-κB or at the post-transcriptional level by CNI-1493, a guanylhydrazone compound which inhibits p38 MAP kinase activity. Previous studies have demonstrated that targeting macrophages and other phagocytic cells by intracellular drug delivery using albumin microcapsules containing either antisense oligomers to NF-κB or CNI-1493 greatly enhances intracellular drug concentration and survival in both endotoxic shock and sepsis models. It is the purpose of this study to determine if microencapsulated drugs acting at different stages in the synthesis of TNF are synergistic. Four groups of 10 rats each were given 15 mg kg−1 of E.coli endotoxin and treated with (1) CNI-1493 1 mg kg−1, (2) antisense oligomers to NF-κB at 100 mcg, (3) CNI-1493 1 mg kg−1 plus antisense κ to NF- at 100 mg kg−1 and (4) CNI-1493 200 mg kg−1 plus antisense oligomer to NF-κB at 200 mg kg−1. TNF and IL1 were measured by ELISA at 4, 8, 24 and 48 h. The rats were observed for 5 days. The combination of CNI-1493 and antisense oligomers to NF-κB inhibited TNF 41% greater that CNI alone and 51% greater than antisense oligomers to NF-κB alone at 4 h after endotoxin administration. Survival at 5 days with CNI alone was 0%, 20% with antisense oligomers to NF-κB and 60% with the combination. In conclusion, synergism in survival occurs using microencapsulated drugs acting at different points in the synthesis of TNF was demonstrated using an in-vivo model of endotoxic shock. Both the amount of TNF inhibition and the mortality were significantly improved with combination therapy. Multiple drugs acting at different sites in the synthesis of TNF may be useful in the treatment of disease states characterized by pro-inflammatory cytokine release.

Activated protein C improves lipopolysaccharide-induced cardiovascular dysfunction by decreasing tissular inflammation and oxidative stress*

Recombinant human activated Protein C (APC) is used as an adjunctive therapeutic treatment in septic shock. APC seemingly acts on coagulation-inflammation interaction but also by decreasing proinflammatory gene activity, thus inhibiting subsequent production of proinflammatory cytokines, NO and NO-induced mediators, reactive oxygen species production and leukocyte-endothelium interaction. The hemodynamic effects of APC on arterial pressure and cardiac function are now well established in animal models. However, the specific effects of APC on heart and vessels have never been studied. To investigate the potential protective properties of therapeutic ranges of APC on a rat endotoxic shock model in terms of anti-inflammatory and cytoprotective pathways. Laboratory investigation. University medical center research laboratory. Rats were exposed to lipopolysaccharide (LPS) (10 mg/Kg intravenous). Endotoxic shock was treated with infusion of saline with or without APC (33 microg/kg/h) during 4 hrs. Hemodynamic parameters were continuously assessed and measurements of muscle oxygen partial pressures, NO and superoxide anion (O2(-)) by spin trapping, of NF-kappaB, metalloproteinase-9 (MMP-9) and inducible NO synthase (iNOS) by Western blotting, as well as leukocyte infiltration and MMP-9 activity were performed at both the heart and aorta level (tissue). APC partially prevented the reduction of blood pressure induced by LPS and improved both vascular hyporeactivity and myocardial performance. This was associated with a decreased up-regulation of NF-kappaB, iNOS and MMP-9. LPS-induced tissue increases in NO and O2(-) production were decreased by APC. Furthermore, APC decreased tissue leukocyte infiltration/activation as assessed by a decrease in myeloperoxidase and matrix metalloproteinase 9 activity. These data suggest that APC improves cardiovascular function: 1) by modulating the endotoxin induced-proinflammatory/prooxidant state, 2) by decreasing endothelial/leukocyte interaction and 3) by favoring stabilization of the extracellular matrix.

S-nitroso human serum albumin given after LPS challenge reduces acute lung injury and prolongs survival in a rat model of endotoxemia

Endotoxemia leads to the induction of inducible nitric oxide synthase (NOS-2) and increased expression of numerous inflammatory mediators contributing to endotoxin-induced acute lung injury. We tested the hypothesis that supplementation of nitric oxide (NO) by the novel NO donor S-nitroso human serum albumin (S-NO-HSA) given after lipopolysaccharide (LPS) challenge may reduce NOS-2 expression, lung inflammation and acute lung injury. Rats were divided into four groups: sham-operated (no treatment), LPS, LPS+HSA (human serum albumin), and LPS+S-NO-HSA. LPS was administered intravenously (20 mg kg(-1)) resulting in acute lung injury and a high mortality rate within 6 h (>90%). LPS-induced lung injury was characterized by an increased lung edema (lung wet/dry weight ratio), pulmonary neutrophil infiltration (myeloperoxidase activity, MPO) as well as a robust inflammatory response [increased expression of intercellular adhesion molecule-1 (ICAM-1), NOS-2, and cyclooxygenase-2 (COX-2)]. Infusion of S-NO-HSA or HSA was started 2 h after LPS and continued for 4 h (total dose of 72 mg kg(-1)) at a rate of 300 microg kg(-1) min(-1). S-NO-HSA but not HSA prolonged survival of endotoxemic rats, reduced the hypotensive response to LPS, minimized LPS-induced lung edema and injury, normalized MPO activity as well as diminished lung expression of pro-inflammatory molecules such as ICAM-1, NOS-2, and COX-2. Continuous supplementation of NO by S-NO-HSA after LPS challenge prevents induction of NOS-2, provides significant protection of endotoxin-induced acute lung injury, and prevents early mortality in endotoxic shock in rats. Our results suggest a potential therapeutic role for S-NO-HSA in endotoxemia.

A novel endotoxin-induced pathway: upregulation of heme oxygenase 1, accumulation of free iron, and free iron-mediated mitochondrial dysfunction

Mitochondria are involved in the development of organ failure in critical care diseases. However, the mechanisms underlying mitochondrial dysfunction are not clear yet. Inducible hemoxygenase (HO-1), a member of the heat shock protein family, is upregulated in critical care diseases and considered to confer cytoprotection against oxidative stress. However, one of the products of HO-1 is Fe2+ which multiplies the damaging potential of reactive oxygen species catalyzing Fenton reaction. The aim of this study was to clarify the relevance of free iron metabolism to the oxidative damage of the liver in endotoxic shock and its impact on mitochondrial function. Endotoxic shock in rats was induced by injection of lipopolysaccharide (LPS) at a dose of 8 mg/kg (i.v.). We observed that the pro-inflammatory cytokine TNF-α and the liver necrosis marker aspartate aminotransferase were increased in blood, confirming inflammatory response to LPS and damage to liver tissue, respectively. The levels of free iron in the liver were significantly increased at 4 and 8 h after onset of endotoxic shock, which did not coincide with the decrease of transferrin iron levels in the blood, but rather with expression of the inducible form of heme oxygenase (HO-1). The proteins important for sequestering free iron (ferritin) and the export of iron out of the cells (ferroportin) were downregulated facilitating the accumulation of free iron in cells. The temporarily increased concentration of free iron in the liver correlated with the temporary impairment of both mitochondrial function and tissue ATP levels. Addition of exogenous iron ions to mitochondria isolated from control animals resulted in an impairment of mitochondrial respiration similar to that observed in endotoxic shock in vivo. Our data suggest that free iron released by HO-1 causes mitochondrial dysfunction in pathological situations accompanied by endotoxic shock.

The effect of panaxadiol saponins on AQP1 expression in myocardial tissues in endotoxic shock rats

The effect of panaxadiol saponins on AQP1 expression in myocardial tissues in endotoxic shock rats

WITHDRAWN: The effect of panaxadiol saponins on AQP1 expression in myocardial tissues in endotoxic shock rats

WITHDRAWN: The effect of panaxadiol saponins on AQP1 expression in myocardial tissues in endotoxic shock rats

Myocardial lactate deprivation is associated with decreased cardiovascular performance, decreased myocardial energetics, and early death in endotoxic shock

We examined whether lactate availability is a limiting factor for heart function during endotoxic shock, and whether lactate deprivation thus induces heart energy depletion, thereby altering cardiovascular performance. The study goals were to determine whether muscle lactate production is linked to beta(2)-stimulation and to ascertain the effects of systemic lactate deprivation on hemodynamics, lactate metabolism, heart energetics, and outcome in a lethal model of rat's endotoxic shock. We modulated the adrenergic pathway in skeletal muscle using microdialysis with ICI-118551, a selective beta(2)-blocker. Muscle lactate formation in endotoxic shock was further inhibited by intravenous infusion of ICI-118551 or dichloroacetate (DCA), an activator of pyruvate dehydrogenase (DCA) and their combination. Muscle lactate formation was decreased by ICI-118551. During endotoxic shock both ICI-118151 and DCA decreased circulating and heart lactate concentrations in parallel with a decrease in tissue ATP content. The combination ICI-118551-DCA resulted in early cardiovascular collapse and death. The addition of molar lactate to ICI-1185111 plus DCA blunted the effects of ICI-118551+DCA on hemodynamics. Survival was markedly less with ICI-118551 than with endotoxin alone. Systemic lactate deprivation is detrimental to myocardial energetics, cardiovascular performance, and outcome.

Protective effect of baicalein against endotoxic shock in rats in vivo and in vitro

Dried roots of Scutellaria baicalensis Georgi ( Huang qin) are widely used in traditional Chinese medicine. Baicalein is a major bioactive flavonoid component of H. qin that shows a wide range of biological activities, including antioxidant and anti-inflammatory actions. We evaluated therapeutic effects and possible mechanisms of action of baicalein on circulatory failure and vascular dysfunction during sepsis induced by lipopolysaccharide (LPS; 10 mg/kg, i.v.) in anesthetized rats. Treatment of the rats with baicalein (20 mg/kg, i.v.) significantly attenuated the deleterious hemodynamic changes of hypotension and tachycardia caused by LPS and significantly inhibited the elevation of plasma tumor necrosis factor α (TNF-α). Baicalein also decreased levels of inducible nitric oxide synthase (iNOS) and the overproduction of NO and superoxide anions caused by LPS. It also increased the survival rate of ICR mice (25–30 g) challenged by LPS (60 mg/kg). Moreover, infiltration of neutrophils into the liver and lungs of rats 6 h after treatment with LPS was also reduced by baicalein. To investigate the mechanism of action of baicalein on sepsis, RAW 264.7 cells were used as a model. Baicalein inhibited iNOS protein production, and suppressed LPS-induced degradation of IκBα, the formation of a nuclear factor kappa B (NF-κB)-DNA complex and NF-κB-dependent reporter gene expression. Thus, the therapeutic effects of baicalein were associated with reductions in TNF-α and superoxide anion levels during sepsis. The inhibitory effects of baicalein on iNOS production may be mediated by inhibition of the activation of NF-κB. Baicalein may thus prove a potential agent against endotoxemia.

Nitric oxide involvement in the hemodynamic response to fluid resuscitation in endotoxic shock in rats

Fluid loading is an essential part of cardiovascular resuscitation in septic shock. We hypothesized that fluid administration increases blood flow velocity and thus endothelial shear stress, causing the release of nitric oxide by the vascular endothelium. Because of endothelial dysfunction in sepsis, this mechanism would be less effective in septic animals. Fluid loading may have different effects in septic compared with control animals. Prospective, randomized, controlled study. Animal research laboratory. Male Sprague-Dawley rats. We tested the involvement of nitric oxide in the fluid-induced cardiovascular response after administration of lipopolysaccharide (5 mg/kg, n = 10) or vehicle (control, n = 10) in rats subsequently randomized after 165 mins to receive L-N(G)-nitroarginine (7.5 mg/kg) or saline (n = 5 in each group). At 180 mins, all animals received hydroxyethyl starch (fluid loading, 15 mL/kg in 15 mins). Reversal of L-N(G)-nitroarginine was studied with an intravenous bolus of L-arginine (300 mg/kg). Lipopolysaccharide injection induced a hypokinetic shock (low blood pressure: -30% +/- 9%, p < .05), low cardiac output (aortic pulsed-Doppler probe: -20% +/- 8, p < .05), and unchanged systemic conductance, which turned into a hyperkinetic shock by fluid loading. Pretreatment with L-N(G)-nitroarginine totally abolished this fluid loading-induced vasodilation in control rats but only partially in lipopolysaccharide-treated rats, suggesting an altered endothelial response after lipopolysaccharide injection. Maximal aortic blood flow acceleration was used as an index of left ventricular systolic function. The improvement of maximal aortic blood flow acceleration observed during fluid loading in lipopolysaccharide-treated or control animals was blunted by L-N(G)-nitroarginine pretreatment, suggesting the involvement of nitric oxide in the myocardial response to fluid loading. These results suggest that the endothelium participates in the hemodynamic response to fluid loading in control rats, but less in rats with septic shock, secondary to an altered nitric oxide-dependent vasodilation.