Endotoxic Shock Group Research Articles

Inhibition of Netosis with PAD Inhibitor Attenuates Endotoxin Shock Induced Systemic Inflammation.

Neutrophils play a pivotal role in innate immunity by releasing neutrophils extracellular traps (NETs). Excessive NETs are detrimental to the local tissue and further exacerbate inflammation. Protein arginine deiminases (PAD) mediate histone citrullination and NET formation that, in turn, exacerbate endotoxin shock damages. In this study, we further investigated the molecular mechanism underlying PAD and NETs in endotoxic stress in mice. The control group mice were injected with solvent, the LPS endotoxic shock group mice were intraperitoneally injected with LPS at 35 mg/kg only, while the LPS and PAD inhibitor YW3-56 treatment group mice were injected with YW3-56 at 10 mg/kg prior to the LPS injection. YW3-56 significantly prolonged the survival time of the LPS-treated mice. NETs, cfDNA, and inflammatory factors were detected by ELISA in serum, paitoneal cavity, and lung at 24 h after LPS administration. Lung injuries were detected by immunostaining, and lung tissue transcriptomes were analyzed by RNA-seq at 24 h after LPS administration. We found that YW3-56 altered neutrophil tissue homeostasis, inhibited NET formation, and significantly decreased cytokines (IL-6, TNFα and IL-1β) levels, cytokines gene expression, and lung tissue injury. In summary, NET formation inhibition offers a new avenue to manage inflammatory damages under endotoxic stress.

Effect of edaravone on apoptosis in hippocampal cells in a rat model of endotoxic shock

Objective To evaluate the effect of edaravone on apoptosis in hippocampal cells in a rat model of endotoxic shock. Methods Thirty-six male Sprague-Dawley rats, weighing 200-250 g, aged 6 weeks, were randomly divided into 3 groups (n=12 each) using a random number table: control group (group C), endotoxic shock group (group ES), and edaravone group (group E). Lipopolysaccharide 10 mg/kg was injected via the femoral vein to establish the model of endotoxic shock in ES and E groups, while the equal volume of normal saline was given in group C. In group E, edaravone 3 mg/kg was intravenously injected immediately after establishment of the model once every 2 h until the animals were sacrificed.The equal volume of normal saline was given instead of edaravone in C and ES groups.At 6 and 12 h after administration of edaravone, 6 rats in each group were sacrificed, and the hippocampi were isolated for determination of malondialdehyde (MDA) content (using thiobarbituric acid method), tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) contents (using enzyme-linked immunosorbent assay), and cell apoptosis in hippocampal CA1 region (by TUNEL assay). The apoptotic index was calculated. Results Compared with group C, the MDA, TNF-α and IL-6 contents were significantly increased at 6 and 12 h after administration of edaravone, and the apoptotic index was increased at 12 h after administration of edaravone in ES and E groups.Compared with group ES, the MDA, TNF-α and IL-6 contents were significantly decreased at 6 and 12 h after administration of edaravone, and the apoptotic index was decreased at 12 h after administration of edaravone in group E. Conclusion Edaravone can reduce apoptosis in hippocampal cells, and the mechanism is associated with the reduced oxidative stress and inflammatory responses in a rat model of endotoxic shock. Key words: Free radical scavengers; Shock, septic; Hippocampus; Apoptosis

Mechanism of electroacupuncture-induced reduction of acute lung injury induced by endotoxic shock in rabbits: the relationship with Nrf2/ARE pathway

Objective To investigate the relationship between the mechanism of electroacupuncture (EA)-induced reduction of acute lung injury induced by endotoxic shock (ES) and nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway in rabbits.Methods Forty healthy male New Zealand white rabbits,aged 2 months,weighing 1.5-2.0 kg,were randomly divided into 4 groups (n =10 each) using a random number table:sham operation group (group S),group ES,EA at acupoints + ES group (group EA),and EA at non-acupoints + ES group (group NA-EA).The animals were anesthetized with iv 20％ urethane 5 ml/kg,tracheostomized and kept spontaneous breathing.ES was induced by iv administration of lipopolysaccharide (LPS) 5 mg/kg in ES,EA and NA-EA groups.The equal volume of normal saline was given in group S.Bilateral 30 min EA (wave length 0.2-0.6 ms,frequency 2/100 Hz,intensity ≤2-3 mA) stimulation of Zusanli and Feishu was performed once a day for 4 days before establishment of endotoxic shock model and during the process of establishment of endotoxic shock model in EA group.In NA-EA group,EA was performed at the points 0.5 cm lateral to the acupoints of Zusanli and Feishu according to the method previously described in group EA.The rabbits were sacrificed at 6 h after LPS or normal saline administration,and lungs were removed for microscopic examination and for determination of wet to dry lung weight ratio (W/D ratio),malondialdehyde (MDA) contents,superoxide dismutase (SOD) activities,and expression of Nrf2 mRNA in lung tissues and Nrf2 in nucleoprotein and total protein.The pathological changes of lung were scored.The ratio of Nrf2 expression in nucleoprotein to Nrf2 expression in total protein (N/T ratio) was calculated.Results Compared with group S,W/D ratio,MDA contents,and lung injury scores were significantly increased,the activities of SOD were decreased,the expression of Nrf2 mRNA in lung tissues and Nrf2 in nucleoprotein and total protein was up-regulated,and N/T ratio was increased in ES,EA and NA-EA groups.Compared with group ES,W/D ratio,MDA contents,and lung injury scores were significantly decreased,the activities of SOD were increased,the expression of Nrf2 mRNA in lung tissues and Nrf2 in nucleoprotein and total protein was up-regulated,and N/T ratio was increased in EA group,and no significant changes were found in NA-EA group.Conclusion The mechanism by which EA reduces acute lung injury induced by ES may be related to activation of Nrf2/ARE pathway and enhancement of antioxidant capacity in rabbits. Key words: Electroacupuncture; NF-E2-related factor 2; Response elements; Shock, septic; Respiratory distress syndrome, adult

Effect of electro-acupuncture at Zusanli and Neiguan acupoints on endotoxic shock-induced myocardial injury in rabbits and the role of heme oxygenase-1

Objective To evaluate the effect of electro-acupuncture (EA) at Zusanli (ST-36) and Neiguan (PC6) acupoints on endotoxic shock (ES)-induced myocardial injury in rabbits and the role of heme oxygenase-1 (HO-1).Methods Sixty healthy male New Zealand white rabbits,aged 2 months,weighing 1.5-2.0 kg,were randomly assigned into 6 groups (n =10 each) using a random number table:sham operation group (group S) ; heme oxygenase-1 inhibitor zinc protoporphyrin-Ⅸ (ZnPP-Ⅸ) group (group Z) ; group ES; EA + ES group (group EES); sham EA + ES group (group SEES); EA + ES + ZnPP-Ⅸ group (group EESZ).The rabbits were anesthetized with intravenous 20％ urethane 5 ml/kg.Right common carotid artery was cannulated for BP monitoring.Ear vein was cannulated for drug administration.ES was induced with lipopolysaccharide (LPS) 5 mg/kg injected intravenously in ES,EES,SEES and EESZ groups,while the equal volume of normal saline was given in S and Z groups.ES was confirmed by decrease in MAP to 75 ％ of the baseline value.ZnPP-Ⅸ 10 μmol/kg (in 1 ml of NaHCO3 50 mmol/L) was injected intraperitoneally at 2 h after LPS or normal saline administration in EESZ and Z groups,while the equal volume of NaHCO3 was injected intraperitoneally in the other groups.In EES and EESZ groups,bilateral 30 min EA stimulation (0.2-0.6 ms,2/100 Hz,2-3 mA) of ST36 and PC6 was performed once a day on days 1-4 before induction of ES and on the day of induction of ES (from the onset of LPS injection until the end of induction of ES).In SEES group,electro-stimulation was performed at the points 0.5 cm lateral to the acupoints of ST36 and PC6 and the method was similar to those previously described in group EES.Blood samples were taken from the right common carotid artery at 6 h after LPS or normal saline administration for measurement of serum tumor necrosis factor-alpha (TNF-α),creatine kinase (CK),and lactic dehydrogenase (LDH) levels.Then the rabbits were sacrificed by exsanguination,and the myocardial tissues were removed for microscopic examination of the pathological changes which were scored and for determination of HO-1 protein (by Western blot) and mRNA (using fluorescence quantitative PCR) expression.Results Compared with group S,the pathological scores and concentrations of serum TNF-α,CK,and LDH were significantly increased,and the expression of HO-1 protein and mRNA was up-regulated in ES,EES,SEES and EESZ groups (P ＜ 0.05),and no significant change was found in the parameters mentioned above in group Z (P ＞ 0.05).Compared with group ES,the pathological scores and concentrations of serum TNF-α,CK,and LDH were significantly decreased,and the expression of HO-1 protein and mRNA was up-regulated in group EES (P ＜ 0.05),while no significant change in the parameters mentioned above was found in SEES and EESZ groups (P ＞ 0.05).Compared with group EES,the pathological scores and concentrations of serum TNF-α,CK,and LDH were significantly increased,and the expression of HO-1 protein and mRNA was down-regulated in group EESZ (P ＜ 0.05).Conclusion EA at ST-36 and PC6 acupoints can attenuate ES-induced myocardial injury in rabbits and upregulation of HO-1 expression and inhibition of inflammatory responses may be involved in the mechanism. Key words: Electric stimulation therapy; POINT ST36 (ZUSANLI) ; POINT PC6 (NEIGUAN) ; Shock,septic; Myocardium; Heme oxygenase-1

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

Role of p38MAPK signaling pathway in up-regulation of heme oxygenase-1 expression in lung tissues in rats with acute lung injury induced by endotoxic shock

Objective To evaluate the role of p38MAPK signaling pathway in the up-regulation of heme oxygenase-1 (HO-1) expression in the lung tissue in rats with acute lung injury (AL1) induced by endotoxic shock.Methods Forty-eight male SD rats,aged 8 weeks,weighing 180-200 g,were randomly divided into 4 groups ( n =12 each):control group ( group C ) ; endotoxic shock group ( group LS );endotoxic shock +SB203580 (a specific p38MAPK inhibitor) group (group LSS) and SB203580 group (group SB).Normal saline 0.5ml was injected via the femoral vein in groups C and SB,while LPS 10 mg/kg (in 0.5 ml normal saline) was injected via the femoral vein in groups LS and LSS.When MAP was decreased to 75％ of baseline value,10％ dimethyl sulfoxide (DMSO) 0.1 ml was infused via the femoral vein in groups C and LS,while SB203580 5 mol/kg (in 10％ DMSO 0.1 ml) was infused via the femoral vein at a rate of 0.01 ml/min in groups LSS and SB.Arterial blood samples were obtained at 6 h after LPS or normal saline was given for blood gas analysis and oxygenation index (PaO2/FiO2) was calculated.Then the rats were sacrificed and the lungs were removed for microscopic examination.The pathological changes of the lung were scored.The lung water content was calculated.The MDA content,SOD activity,and expression of HO-1 mRNA and protein,p38MAPK protein and phospharylated p38MAPK (p-p38MAPK) protein were determined.Results Compared with group C,the oxygenation index and SOD activity were significantly decreased,the pathological score,lung water content and MDA content were significantly increased,and the expression of HO-1 mRNA and protein and p-p38MAPK protein was significantly up-regulated ( P＜0.05),while no significant change was found in p38MAPK protein expression in groups LS and LSS,and no significant change was found in the indexes mentioned above in group SB (P＞0.05).Compared with group LS,the oxygenation index and SOD activity were significantly increased,the pathological score,lung water content and MDA content were significantly decreased,the expression of HO-1 mRNA and protein was significantly up-regulated,and p-p38MAPK protein expression was down-regulated ( P＜0.05),and no significant change was found in p38MAPK protein expression in group LSS ( P＞0.05).Conclusion The inhibition of p38MAPK signaling pathway can lead to the up-regulation of HO-1 expression in lung tissues in rats with ALI induced by endotoxic shock. Key words: p38 Mitogen-activated protein kinases; Hemne oxygenase-1; Lung; Shock,septic; Respiratory distress syndrome,adult

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

Effects of Microbubbles and Ultrasound on the Microcirculation: Observation on the Hamster Cheek Pouch

In view of the debate on the safety of using ultrasound associated with microbubbles, we investigated the microvascular effects in situations of potential clinical interest. Ultrasound, microbubbles, and their association were evaluated on the cheek pouch microcirculation in 96 male hamsters (n = 6 in each group): control; ischemia-reperfusion, 30 minutes total ischemia followed by reperfusion; hyperinsulinemia and hyperglycemia (substitution of the drinking water by 10% fructose solution for 3 months); and endotoxic shock (induced by Escherichia coli lipopolysaccharide). The heart rate, mean arterial pressure, number of rolling and adhered leukocytes, and arteriolar and venular diameters were analyzed. Heart rate and mean arterial pressure were lower in the endotoxic shock group than in the control group. Ultrasound alone or associated with microbubbles decreased the number of rolling and adhered leukocytes in the ischemia-reperfusion and hyperinsulinemia and hyperglycemia groups and increased venular diameter in the ischemia-reperfusion group. The use of ultrasound decreases inflammation. Although it has not been established that pseudo-anaphylaxis can be assessed by intravital microscopy, microbubble administration does not increase venular leukocyte adhesion.

Changes in expression of neuroglobin in brain tissues and plasma in a rat model of endotoxic shock

Objective To investigate the changes in the expression of neuroglobin (Ngb) in the frontal lobe cortex, hippocampus, cerebro-spinal fluid (CSF) and plasma in a rat model of endotoxie shock. Methods Seventy SD rats of both sexes aged 7 weeks weighing 250-300 g were randomly divided into control group (group C, n = 10) and endotoxic shock group (group ES, n =60). LPS 16 mg/kg was injected via the vein in the tail in group ES. In group C, equal volume of normal saline was administered iv instead of LPS. Blood and CSF samples were taken and frontal lobe cortex and hippocampua were removed at 3, 6, 12, 24, 48, and 72 h after LPS administration for determination of Ngb expression by ELISA and Western blotting. Cerebral water content was measured --brain water content = (wet weight- dry weight) ÷ wet weight x 100%.Results The brain water content was significantly increased after LPS administration and peaked at 48 h after LPS. The expression of Ngh was significantly higher in group ES than in group C and peaked at 48 h after LPS (P < 0.01). Conclusion The up-regulation of Ngb induced by endotoxic shock is time-dependent and is one of the endogenous neuron-protective mechanisms of endotoxie shock. Key words: Globulins; Shock,septic

RELATIONSHIP BETWEEN BIOPTERIN FORMATION AND MULTIPLE ORGAN DYSFUNCTION IN RATS WITH ENDOTOXIC SHOCK

Objective: The current experiment was performed to study the relationship between biopterin formation and multiple organ dysfunction in rats with endotoxic shock. Methods: A rat model of endotoxic shock was reproduced by a bolus injection of lipopolysaccharide (10 mg/kg, i.v.). 104 male Wistar rats were randomly divided into normal controls (n = 8), endotoxic shock group (n = 48), and 2,4-diamino-6-hydroxy-pyrimidine (DAHP) treatment group (n = 48). At serial time points animals in each group were sacrificed, serum samples and tissue specimens from liver, lungs as well as kidneys were harvested. Tissue biopterin contents were measured by reverse-phase HPLC/fluorescence detection. GTP cyclohydrolase I (GTP-CHI) mRNA expression was determined by RT-PCR. Results: Compared to normal controls, tissue biopterin contents in liver, lungs and kidneys were markedly elevated from 0.5 to 2 hrs after endotoxin challenge (P < 0.01), peaking at 6-12 hrs, and gradually decreased afterwards. Concomitantly, GTP-CHI mRNA levels were significantly increased in liver, lungs and kidneys at 0.5 to 2 hrs after endotoxin challenge, and high values were maintained up to 48 hrs. Treatment with DAHP, an inhibitor of tetrahydrobiopterin synthesis, could significantly reduce tissue biopterin contents at 2-24 hrs in rats after lipopolysaccharide challenge (P < 0.05 or 0.01). Hepatic and renal GTP-CHI mRNA expressions in the DAHP treatment group were markedly down-regulated compared with the endotoxic shock group at various intervals, and they tended to approach normal range at 12 hrs in lungs. Additionally, organ functional indexes including serum ALT, AST, BUN, Cr levels and pulmonary myeloperoxidase activity were significantly decreased in the DAHP-treated group compared to the endotoxic shock group at 0.5-24 hrs. Conclusions: These data suggest that biopterin formation is involved in the pathogenesis of endotoxin-induced acute organ injury, and inhibition of tetrahydrobiopterin synthesis pathway attenuates inflammatory response and prevents multiple organ dysfunction syndrome as well as septic shock.

The mechanisms of extracellular-signal regulated protein kinase pathway in biopterin induction in rats with endotoxic shock

To observe the influence of treatment with the inhibitor of extracellular-signal regulated protein kinase (ERK) signal transduction pathway on the expression of biopterin/nitric oxide (NO) as well as the activation of nuclear factor-kappaB (NF-kappaB), and to clarify the potential cross-talk regulation mechanisms between ERK and NF-kappaB pathway in biopterin-mediated NO induction in rats with endotoxic shock. Using an endotoxic shock model, 60 male Wistar rats were randomly divided into normal controls (n = 8), endotoxic shock group (n = 32) and PD98059 treatment group (n = 20). At serial time points animals in each group were sacrificed, and tissue samples from liver, lungs as well as kidneys were harvested to detect NF-kappaB activity, guanosine triphosphate-cyclohydrolase (GTP-CHI) and inducible nitric oxide synthase (iNOS) mRNA expression. Biopterin and NO levels in plasma and tissues were also assayed. It was found that after lipopolysaccharide (LPS) challenge, GTP-CHI mRNA expression and biopterin levels significantly elevated in liver, lungs and kidneys, keeping at high values up to 24 h, so did the values of iNOS mRNA expression and NO levels. NF-kappaB DNA binding activity was enhanced rapidly in various tissues, peaking at 2 h after LPS challenge. Treatment with PD98059, an inhibitor of ERK signal transduction pathway, could significantly inhibit GTP-CHI mRNA expression in kidneys, and GTP-CHI mRNA expression in liver and lungs showed certain down-regulation tendency. At the same time, biopterin level was significantly decreased in plasma, liver and kidneys at 12 h. Similarly, iNOS/NO induction at early stage markedly decreased in various tissues. In addition, treatment with PD98059 reduced NF-kappaB DNA binding activity in liver, lungs, as well as kidneys at 2-6 h, 2 h, 24 h and 24 h after LPS challenge, respectively. Inhibition of ERK pathway could partially inhibit the production of biopterin/NO as well as the activation of NF-kappaB pathway, which indicated that cross-talk regulation seems to be existed between ERK and NF-kappaB pathway, and they might be involved in the regulatory process of biopterin-mediated nitric oxide induction in rats with endotoxic shock.

Treatment of Experimental Septic Shock with Microencapsulated Antisense Oligomers to NF-κB

NF-kappaB is an ideal target for inhibition of proinflammatory cytokines. The purpose of this study was to determine if microencapsulated antisense oligomer to NF-kappaB can inhibit proinflammatory cytokine release in response to Escherichia coli endotoxin and bacteria. Microencapsulation takes advantage of the phagocytic function of the macrophage to deliver the oligomer intracellularly and enhance the effect. Albumin microcapsules 1 microm in size were prepared by a nebulization method containing antisense oligomers to NF-kappaB. E. coli endotoxin was incubated in 1 ml aliquots of whole blood. Microencapsulated antisense to NF-kappaB was given, and the inhibition of tumor necrosis factor (TNF), interleukin-1 (IL-1), IL-6, and IL-8 was compared with similar amounts of oligomer in solution. Endotoxic shock was produced in rats using E. coli endotoxin (15 mg/kg). Peritonitis was induced by injecting 10(10) CFU E. coli. Cytokines were measured after simultaneous and delayed (4 h) administration of antisense to NF-kappaB in microcapsules and solution form. TNF was suppressed by 81% in whole blood, 56% in the endotoxic shock model, 89% in the peritonitis model (simultaneous treatment), and 56% in the delayed treatment group. Survival was 70% in the endotoxic shock group, 80% in the simultaneous peritonitis group, and 70% in the delayed treatment group. Microcapsule treatment using antisense to NF-kappaB suppressed TNF and IL-1 levels and mortality significantly better than all solution treatment groups in the whole blood model, endotoxic shock model, and peritonitis model.

Effect of MCI-154, a calcium sensitizer, on calcium sensitivity of myocardial fibers in endotoxic shock rats.

This study was designed to investigate the effect of a calcium sensitizer on the Ca2+ sensitivity of myocardial fibers in endotoxic shock rats. Right ventricular papillary muscles from sham shock or endotoxic shock rats were skinned by incubation in saponin solution. Forces of the skinned muscles were recorded when they were activated sequentially by different pCa (-log[Ca2+]) activating solutions with or without positive inotropic agents. Tension-pCa relationship curve of skinned fibers delineated the affinity of troponin C(TnC) for Ca2+ and the medium value pCa50 (pCa required for producing 50% of maximal Ca2+-activated tension) was taken as the quantitative index of Ca2+ sensitivity of TNC. It was found that the maximal Ca2+ activated tension (Tmax) was lower, tension-pCa relationship curve was shifted rightward, and the pCa50 was reduced significantly in endotoxic shock group compared with that of sham shock group. Milrinone could not counteract the above abnormalities. However, when skinned right ventricular papillary fibers from endotoxic shock rats were dealt with activating solutions containing 1 x 10(-5) M MCI-154, the Tmax was significantly increased, the tension-pCa relationship curve was shifted leftward. The pCa50 in MCI-154 group was increased to an extent similar to that of sham shock group and markedly higher than the values of endotoxic shock group and milrinone group. Furthermore, such effects of MCI-154 were concentration dependent. It can been concluded that the sensitivity of cardiac contractile proteins to Ca2+ in endotoxic shock rats is decreased. MCI-154, a calcium sensitizer, can significantly reverse the decreased sensitivity and increase Tmax of myocardial muscles from endotoxic shock rats.

Endogenous neuropeptide Y mediates vasoconstriction during endotoxic and hemorrhagic shock

Neuropeptide Y (1–36), NPY, is a sympathetic vasoconstrictor whose activities in blood vessels is determined by the presence of vasoconstrictive Yl receptors and the enzyme dipeptidyl peptidase IV (DPPIV), which converts NPY to non-vasoconstrictive peptides. While the role of the NPY system has been established during cold water stress, its role in hypotensive conditions has not; yet, exogenous NPY improves hemodynamics and survival in rats with endotoxic shock. We used a new selective non-peptidergic Y1 receptor antagonist, BIBP-3226, to determine the role of the endogenous NPY/Yl system in endotoxic shock (induced by i.v. injection of 10 mg/kg of Escherichia coli lipopolysaccharide 0127:B8, LPS) and hemorrhagic shock (bleeding of 15 ml/kg over 1.5 min). Conscious rats received a bolus of BIBP-3226 or the vehicle 5 min before endotoxin challenge or induction of hemorrhage, followed by continuous infusion. Mean arterial pressure (MAP) at 5 min after LPS administration dropped in the control group by 15%, compared to 36% in the BIBP-3226-treated group ( p<0.01). Similarly, the hemorrhage-induced drop in MAP in the control group was 32% at 5 min, compared to 53% in the BIBP-treated rats ( p<0.01). Plasma NPY levels were unchanged in the endotoxic shock group, but were significantly elevated in the hemorrhagic shock group. BIBP-3226 pretreatment abrogated the increased plasma NPY levels after hemorrhagic shock. Endogenous NPY contributes to blood pressure recovery during endotoxic and hemorrhagic shock.

Renal gluconeogenesis and blood flow during endotoxic shock.

To determine whether endotoxic shock decreases the renal gluconeogenic capacity and the renal artery blood flow. An in-vivo, murine, nonrecirculating kidney perfusion model was studied in a trauma research laboratory. Each of 12 fasted, male Holtzman rats (shock n = 6, control n = 6) was injected with 1 mL of normal saline or endotoxin (20 mg/kg). Five hours after the injection, all the rats were anesthetized and blood samples were obtained for the determination of the plasma glucose. Right renal artery blood flow was measured by an ultrasonic small-animal flow meter. The kidney was then perfused via the renal artery with 37 degrees C, oxygenated, glucose-free Krebs-Henseleit solution in the presence of 100 mumol of phloridzin to inhibit the cellular uptake of glucose. Renal glucose production was determined by measuring glucose in both renal vein effluent and urine. After 30 minutes of equilibration, 5 mmol of lactate and 0.5 mmol of pyruvate were added to the perfusate as a gluconeogenic substrate. Renal vein and ureteral effluent samples were collected after 5, 10, and 15 minutes. The endotoxic shock group showed hypoglycemia (p < 0.05) as well as a decrease in renal artery blood flow (p < 0.05). Gluconeogenic stimulation was demonstrable in both the control and the endotoxic shock groups after 15 minutes of perfusion with substrate (p < 0.05). However, renal gluconeogenesis was significantly attenuated in the endotoxic shock group compared with the control. Renal glucose production in response to a gluconeogenic substrate is significantly attenuated during the hypoglycemic phase of endotoxic shock. Endotoxic shock also causes a significant decrease of renal artery blood flow.

Evaluation of shock-related cardiotoxic peptide.

The aim of the present work is to confirm the presence of MDF (myocardial depressant factor), which has long been postulated to be one of the cardiotoxic substances in the shock state. Twenty male mongrel dogs were divided into two groups, a hemorrhagic shock group (n = 10) and an endotoxic shock group (n = 10). Blood samples were obtained from each animal at 1, 2, 4, and 7 h after hypotensive events occurred. Inotropic properties of the plasma samples were evaluated by the isometric contraction of a cat papillary muscle preparation, and chromatographic analysis was performed on the peptides in the plasma. Developed tension of the muscle was increased significantly by changing the bathing medium from Krebs-Henseleit solution to plasma obtained 1 to 4 h after the onset of hemorrhagic and endotoxin induced hypotension. The positive inotropic change was associated with a significant increase in plasma epinephrine concentration. None of these plasma samples possessed a negative inotropic effect (i.e., the property of MDF activity). The elution profile by gel column chromatography of samples obtained from shocked animals was almost identical to that recognized as MDF. However, the presence of MDF was not confirmed by column parameters and color development by the ninhidrin reaction. In conclusion, we found no evidence to support the presence of cardiotoxic peptide in plasma of shocked animals.

Endotoxic shock and its effects on hepatobiliary scanning in dogs.

Hepatobiliary scans were obtained with Tc-99m-disofenin in 15 dogs. Of these, 5 served as controls, 5 were infused with E. coli endotoxin for 4 hours (endotoxic shock group), and 5 were bled to a mean pressure similar to that of the endotoxic shock group (hemorrhagic shock group). Scans of the controls and hemorrhagic shock group were identical. Scans of the endotoxic shock group were markedly abnormal, with a prolonged hepatic phase and little excretion of isotope into the biliary tract, a pattern characteristic of mechanical obstruction of the common bile duct. These results should alert the clinician to the potential danger of abnormal hepatobiliary scans in the septic patient.