Endotoxin Shock In Rats Research Articles

Hirulog effect in rat endotoxin shock

Hirulog TM is a thrombin catalytic site inhibitor which exhibits specificity for the anionic binding exosite of alpha thrombin. Here, we have evaluated the effect of Hirulog TM (1, 5 and 10 mg/kg, 30 min pretreatment) in a rat model of endotoxemia. Intravenous injection of lipopolysaccharide from E. coli (25 mg/kg; serotype 0127:B8) caused decreases in blood pressure which were significantly reduced (about 60%) in animals pretreated with Hirulog TM. Rat survival to endotoxin was significantly increased in Hirulog TM pretreated group (5 and 10 mg/kg) up to 24 hours. Hirulog TMat the dose of 10 mg/kg inhibited both endotoxin-induced leukopenia at 30 and 60 minute points and thrombocytopenia at 30 minute point but not at 90 and 120 minute points. Fibrinogen levels were significantly reduced after 2 hours following endotoxin administration. Pretreatment with Hirulog TM (5–10 mg/kg i.v.) 30 min prior to administration of endotoxin prevented changes in fibrinogen plasma levels. These results demonstrate that Hirulog TM-induced inhibition of thrombin is effective in reducing toxic and lethal effects of endotoxin.

The effect of dietary nucleic acid deficiency and the administration of a nucleotide and nucleosides mixture solution on endotoxin shock in rats.

The importance of dietary nucleic acid in modulation of immune function without disease has been reported in nutritional disorder except under surgical stress. Dietary nucleic acid deficiency decreases T lymphocytes function1 and dietary ribonucleic acid (RNA) enhances immune response2. However, it is not known whether dietary nucleic acid influences on macrophage function. Recently, monocytes/macrophages are considered as key factors in the pathogenesis of systemic inflammatory response leading to septic shock by producing humoral mediators under endotoxin stimulation3, 4. Therefore, the aim of this study is to evaluate the influence of dietary nucleic acid deficiency on endotoxin shock and macrophage functions stimulated with lipopolysaccharide (LPS), which is the major component of endotoxin. Then, the effect of intraperitoneal administration of a nucleotide and nucleosides mixture solution (OG-VI)5 was evaluated.KeywordsPeritoneal MacrophageTotal Parenteral NutritionMacrophage FunctionChow GroupEndotoxin ShockThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Multiple functions of nitric oxide in pathophysiology and microbiology: analysis by a new nitric oxide scavenger.

A wide range of biological functions of nitric oxide (NO) was analyzed using a newly discovered nitric oxide scavenger, 2-phenyl-4,4,5,5-tetramethylimidazolineoxyl-1-oxyl-3-oxide (PTIO) or its water-soluble derivative carboxy-PTIO. The chemistry is very simple in that NO was oxidized by PTIO, yielding one mole each of NO2 and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl. Based on the potent NO-scavenging activity of PTIO derivatives, the diverse functions of NO under physiological states as well as various pathological conditions such as endotoxin shock and viral diseases are now explicated. It was found that PTIO and carboxy-PTIO showed significant inhibitory activity against a series of biological actions of NO: (1) endothelium-dependent vascular relaxation in an ex vivo system, (2) pathogenicity of NO produced excessively in endotoxin shock in rats and in influenza virus pneumonitis in mice, and (3) enhanced vascular permeability in solid tumors mediated by NO. PTIO directly extinguishes NO generated by NO synthase (NOS) without affecting NOS activity, which is a clear contrast to NOS inhibitors. Therefore, characterization of this unique mode of action of PTIO appears to be helpful not only in understanding of the pathophysiological role of NO but also in the treatment of various diseases caused by excessive production of NO.

O-47 - Expression of cyciooxygenase-2 in endotoxin shock rats.

O-47 - Expression of cyciooxygenase-2 in endotoxin shock rats.

Cloricromene inhibits the induction of nitric oxide synthase

The effect of cloricromene, a coumarine derivative, was investigated on the lipopolysaccharide-stimulated nitric oxide (NO) synthase induction in intact aortas from endotoxin shocked rats and in the murine macrophage cell line J774. Rings of thoracic aortas from lipopolysaccharide (4 mg/kg, i.v.)-shocked rats, contracted with phenylephrine, showed a progressive decrease in tone, that was a of greater magnitude than that of aortas from naive rats. Moreover, a decreased response to the constrictor effect of phenylephrine was observed in aortas from shocked rats. In vivo treatment with cloricromene (2 mg/kg, i.v.) 30 min before lipopolysaccharide administration partially prevented the loss in tone of aortic rings and improved their reactivity to phenylephrine. Murine J774 macrophages activated with lipopolysaccharide (100 ng/ml) produced significant amounts of nitrites (NO 2 −; 28.2 ± 3.5 nmol/10 6 cells per 24 h). Cloricromene (2, 20 or 200 μM) added to the cells concomitantly with lipolysaccharide inhibited NO 2 − production in a concentration-dependent manner. Maximum inhibition (84.0 ± 8.0%) was observed when cloricromene (200 μM) was added to the cells 6 h before lipopolysaccharide, whereas it was ineffective when given 6 h after endotoxin. These results demonstrate that cloricromene inhibits the expression but not the activity of the inducible NO synthase.

Natural cytokine complex in therapy of penetrating corneal wounds in rabbits

In initial and intermediate periods of endotoxin shock in rats and dogs significant micropinocytosis in the epithelial cells of distal tubules and collecting ducts are observed. On the stage of late endotoxemia in rats transepithelial pinocytosis disappears. Existence of correlative connections between ultrastructural changes in neurosecretory system and epithelial cells responsible for facultative reabsorption in different periods of experimental endotoxemia have been shown.

Cloricromene, a coumarine derivative, protects against lethal endotoxin shock in rats

Endotoxin shock was induced in male rats by an intravenous (i.v.) injection of Salmonella enteriditis lipopolysaccharide (LPS; 20 mg/kg i.v.). Survival rate, macrophage and serum tumor necrosis factor (TNF-α), mean arterial blood pressure (MAP) and white blood cell count were then evaluated. Furthermore the in vitro effect of cloricromene on peritoneal macrophage phagocytosis and TNF-α release by primed peritoneal macrophages was investigated. LPS administration caused animal death (0% survival 24 h after endotoxin challenge), hypotension, marked leukopenia and increased the levels of TNF-α in both serum and macrophage supernatants. Cloricromene administration (0.5, 1 and 2 mg/kg i.v. 15 min after endotoxin) protected against LPS-induced lethality (100% survival rate 24 h after endotoxin challenge), reverted LPS-induced hypotension and leukopenia, and decreased TNF-α in both serum and macrophage supernatants. Finally, cloricromene, added in vitro to peritoneal macrophages collected from endotoxin-treated rats increased macrophage phagocytosis and reduced TNF-α formation by activated mononuclear phagocytes. Our data suggest that cloricromene increases survival rate in endotoxin shock through an inhibition of TNF-α production.

Lack of involvement of neutrophil-derived nitric oxide in the loss of contraction tonicity on aorta from endotoxin shocked rats

Lack of involvement of neutrophil-derived nitric oxide in the loss of contraction tonicity on aorta from endotoxin shocked rats

Superoxide production of polymorphonuclear leukocytes in endotoxin shock and antioxidative effect of coenzyme Q10

The present study was designed to determine the superoxide production of polymorphonuclear leukocytes (PMN) in endotoxin shock and the antioxidative effect of coenzyme Q10. PMN were collected from rats before and after the intravenous administration of endotoxin. PMN were also collected from healthy humans. Superoxide production of PMN was measured by the cytochrome C method. Lipid peroxide in the liver was examined by the TBA method. Twelve hours after the intravenous administration of 5 mg/kg endotoxin, superoxide production of PMN was 13 times higher than that in the control rats, and the amount of lipid peroxide in the liver was increased. In coenzyme Q10 treated endotoxin shock rats, superoxide production was significantly decreased, and lipid peroxide production in the liver was also inhibited. These findings suggest that endotoxin has a priming effect on the superoxide production of PMN and induces lipid peroxidation. Furthermore coenzyme Q10 has an anti-endotoxin shock effect by inhibiting the superoxide production of PMN and lipid peroxidation in the liver.

Enhanced expression of group II phospholipase A2 gene in the tissues of endotoxin shock rats and its suppression by glucocorticoid

We studied the regulation of group II phospholipase A2 (PLA2-II) gene in vivo, using endotoxin shock rat as a model for systemic inflammation. Administration of endotoxin into rats increased PLA2 activity in the plasma, as described by Vadas and Hay, using endotoxin-challenged rabbit. Specific absorption of this activity by anti-PLA2-II antibody indicated that the released PLA2 was PLA2-II. The levels of PLA2-II mRNA were elevated in the aorta, spleen, lung, and thymus but not in the liver and kidney. The tissues with high PLA2-II mRNA contents released a greater amount of PLA2-II than the tissues of control rats. These results suggest that in endotoxin shock rats, PLA2-II is synthesized de novo in the above tissues and released into circulation. Furthermore, our present study demonstrates that glucocorticoid suppresses the enhanced expression of the PLA2-II gene in the tissues of endotoxin shock rats.

Influence of essential fatty acid deficient diet on some manifestations of endotoxin shock in rats

Influence of essential fatty acid deficient diet on some manifestations of endotoxin shock in rats

Attenuation of arterial blood pressure fall in endotoxin shock in the rat using the competitive bradykinin antagonist Lys-Lys-[Hyp2, Thi5,8, DPhe7]-Bk (B4148).

The selective competitive bradykinin (Bk) antagonist, B4148 (Lys-Lys-[Hyp2, Thi5,8, DPhe7]-Bk) infused at 100 micrograms kg-1 min-1 into rats produced a significant inhibition of the hypotensive effect of Bk and had no effect against acetylcholine-induced responses. In a rat model of endotoxin shock, the fall in mean arterial blood pressure in response to an intravenous injection of lipopolysaccharide from E. coli was significantly attenuated by the same infusion of B4148 compared to controls. These findings suggest that kinins are involved in the hypotensive response to endotoxin shock in rats. The development of potent Bk antagonists offers a new experimental approach for evaluating the role of kinins in this and other disease states and potential therapy in such disorders.

Inotropic Interactions of Dichloroacetate with Amrinone and Ouabain in Isolated Hearts from Endotoxin-Shocked Rats

The inotropic effects of ouabain and amrinone singly and in combination with dichloroacetate (DCA) were assessed using isolated working perfused hearts from endotoxin-shocked (LD50/6 h) rats, with glucose and free fatty acids as substrates. Amrinone (2.7 X 10(-4) M) and ouabain (10(-5) M) alone improved myocardial mechanical performance from 25 to 75%, depending on the preload. Amrinone was more effective than ouabain at all left atrial filling pressures tested. DCA enhanced the inotropic effect of both compounds, improving myocardial work greater than 65% in combination with ouabain (at low filling pressures) to 125% with amrinone (at high filling pressures). Glucose oxidation rose two- to threefold when DCA was present with either drug. Ouabain was without effect on pyruvate dehydrogenase (PDH) activity; however, when present with DCA, PDH activity increased fourfold. Amrinone alone augmented PDH activity 2.5 times as compared with controls, and 4.5 times when combined with DCA. All three compounds individually elevated myocardial ATP levels, but in contrast to the inotropic effects, when used in combination caused no further increase in ATP. Myocardial cyclic AMP (cyclic AMP) levels were augmented five times control values in the presence of amrinone. The simultaneous presence of DCA and amrinone did not further augment the myocardial concentration of cAMP. DCA alone enhanced the myocardial oxidation of glucose in isolated myocardial cells from endotoxin-shocked animals. In contrast, ouabain and amrinone did not affect cellular glucose oxidation. These data indicate that the provision of DCA can enhance the inotropic effect of amrinone and ouabain on the isolated working heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Salutary effects of the prostacyclin analogue CG 4203 in lethal endotoxemia in rats

In pentobarbitone anesthetized rats infusion of E. coli endotoxin (0.42 mg·kg −1·min −1 for 4 hours) produced 96% lethality within 6 hours. Transient decrease in mean arterial blood pressure, thrombocytopenia, leukopenia, loss of plasma fibrinogen, fibrin deposits in renal glomeruli, hemolysis and decrease in arterial oxygen tension and pH were observed. Infusion of the prostacyclin analogue CG 4203 (0.464 and 1.0 μg·kg −1·min −1 for 6 hours), starting concomitantly with the endotoxin infusion, improved the survival rate to 95 and 100%. Blood pressure during endotoxemia was slightly lower in CG 4203 treated rats than in vehicle controls. CG 4203 infusion marginally attenuated thrombocytopenia and obviously inhibited leukopenia, but did not effect fibrinogen consumption in endotoxemic rats. Incidence of glomerular fibrin deposits was dose dependently and significantly reduced by CG 4203. The lower dose reduced and the higher dose completely prevented the occurence of hemolysis. Acidotic changes were not observed in CG 4203 treated endotoxin-shocked rats. Also with treatment starting 1 hour after the onset of endotoxemia CG 4203 in the same doses significantly inhibited the endotoxin-induced lethality. As protective mechanisms against lethal rat endotoxemia the prostacyclin-like hemodynamic, fibrinolytic, rheological and membrane stabilizing properties of CG 4203 are discussed.

P-152 - Protective effect of methylprednisolone suleptanate on experimental endotoxin shock in rats

P-152 - Protective effect of methylprednisolone suleptanate on experimental endotoxin shock in rats

Choice of anesthetic alters the circulatory shock pattern as gauged by conscious rat endotoxemia.

A standardized rat endotoxin shock model was used to assess the differential effects of four commonly used anesthetics upon hemodynamics before and during endotoxin shock. Forty-nine male Sprague-Dawley rats weighing 307 +/- 4 g were divided into five groups:freely-moving conscious, enflurane (2%), isoflurane (1.4%), pentobarbital (6 mg.kg-1.h-1 i.v.), and ketamine (45 mg.kg-1.h-1 i.v.). Anesthetic doses were chosen as 1.0 MAC equivalent. Anesthetized rats were intubated and ventilated with oxygen. The right carotid artery was cannulated with a thermocouple-catheter for aortic blood pressure, heart rate, and thermodilution cardiac output measurements. The right jugular vein was cannulated for measurement of central venous pressure and for i.v. injections. Data were collected over a 30-min baseline period and for 4 h after an i.v. bolus of endotoxin (40 mg.kg-1, LD100 within 24 h). Gross small intestinal pathology was rated on a 0-4 scale. Anesthetic effects were judged in terms of significant deviations from the awake data on each parameter. Despite differing patterns, total deviations were similar for enflurane, ketamine, and pentobarbital, although the latter drug was the least preferable due to particularly high systemic vascular resistance. Significantly less hemorrhagic small intestinal pathology occurred with enflurane. Ketamine offered no advantage over the inhalation anesthetics. Among the four anesthetics tested, results were closest to the awake pattern with isoflurane anesthesia, thus making it the logical choice for hemodynamic studies in experimental shock research.

Changes in regional plasma extravasation in rats following endotoxin infusion

Regional differences in plasma extravasation during endotoxin shock in rats and a possible relationship with changes in regional blood flow were studied with radioactive isotopes ( 125I-HSA, 51Cr-labeled red blood cells, microspheres) in anesthetized rats (pentobarbital). Shock was induced by intravenous infusion of endotoxin ( Eschericia coli; 10 mg·kg −1) for 60 min (starting at t = 0); at t = 120 min, the experiments were terminated. These rats ( n = 8) were compared with time-matched control rats ( n = 8). A third group (rats killed 7.5 min after injection of 125I-HSA, i.e., no extravasation; n = 8) served as baseline. The amount of plasma extravasated in 2 hr of endotoxin shock was significantly increased over control values in skin (by 67%), colon (88%), skeletal muscle (105%), stomach (230%), pancreas (300%), and diaphragm (1300%). Losses of 125I-HSA into intestinal lumen and peritoneal cavity had also increased over control values by 146 and 380%, respectively. Blood flow was compromised in most organs except heart and diaphragm. Extravasation when normalized for total plasma supply was correlated with total blood supply: the more the blood supply decreased, the higher the normalized extravasation. In the diaphragm, however, blood supply and plasma leakage increased together. Decreased blood supply and plasma extravasation may be related but they could also be simultaneously occurring independent phenomena with a common origin.

BAY k 8644, a calcium channel agonist, reverses hypotension in endotoxin-shocked rats

The hypotension and depressed myocardial function frequently observed in endotoxin-induced shock are difficult to overcome pharmacologically. In this paper we demonstrate that the calcium channel agonist BAY k 8644 potently elevates blood pressure in endotoxin-shocked rats. A one time dose as low as 10 μg/kg of BAY k 8644 significantly elevated mean arterial pressure (MAP) in endotoxin-treated hypotensive rats while having minimal effects in normal rats. The maximum BAY k-induced percentage increase in MAP was greater in endotoxin-treated rats when compared with saline-treated control (153% vs. 120% increase respectively). BAY k 8644 also caused a dose-dependent decrease in heart rate of 37% in endotoxin-treated rats and 39% in control rats (NS vs. control). No differences in the regulatory properties of [ 3H]nitrendipine binding sites were discerned comparing control and endotoxin-treated rats. Thus, the enhanced activity of BAY k 8644 in hypotensive rats was not due to augmented affinity for the cardiac dihydropyridine binding site. These results demonstrate that the use of calcium channel agonists might represent a unique pharmacologic approach in pathologic states characterized by hypotension and diminished cardiac function.

Effects of Superoxide Dismutase and Catalase on Endotoxin Shock in Rats

The effects of superoxide dismutase (SOD) and catalase on endotoxin-induced experimental shock were studied in rats. Experimental shock was induced by a single intravenous injection of endotoxin at a dose of 100mg/kg. After the injection, systolic blood pressure was reduced and heart rate was increased. Activities of serum lysosomal enzymes, such as acid phosphatase, β-glucuronidase, and cathepsin B, were increased. Serum thiobarbituric acid-reactive substances, which are important and damaging products of free radical lipid peroxidation, were significantly increased. These changes were most remarkable at 45min after the injection of endotoxin. By the subcutaneous injection of SOD (50mg/kg) 12 and 1h before the administration of endotoxin (100mg/kg), the reduction of systolic blood pressure and the increase in serum acid phosphatase, β-glucuronidase, and cathepsin B activities were significantly inhibited. By the subcutaneous injection of catalase (1.0mg/kg) 12 and 1h before the treatment with endotoxin, the decrease in systolic blood pressure and the increase in acid phosphatase and cathepsin B activities were significantly inhibited. These results indicate that oxygen-derived free radicals, such as superoxide and hydrogen peroxide, can affect the experimental shock states.

Effect of red blood cells and red blood cell ghosts on reticuloendothelial system function

Previous studies have shown that hepatic phagocytosis of red blood red (RBC) stroma can depress reticuloendothelial system (RES) phagocytic function and increase susceptibility to shock. Since the RBC stroma used in these experiments contained substantial amounts of adherent hemoglobin, the present study was carried out to evaluate the role of the hepatic uptake of RBC membrane material on RES phagocytic function and susceptibility to endotoxin shock in rats. Neuraminidase-treated RBC which contained normal amounts of hemoglobin and RBC ghosts which were hemoglobin-free were used. Both preparations were removed from the circulation primarily by the liver. RES phagocytic function was depressed following the hepatic uptake of 29 × 10 8 neuraminidase-treated RBC and 26 × 10 8 RBC ghosts. RES uptake of neuraminidase-treated RBC ghosts associated with an increase in susceptibility to endotoxin shock, but RBC ghosts did not affect shock susceptibility. Thus, RBC ghosts and intact RBC are equally effective in depressing RES phagocytic function, but RBC ghosts did not affect susceptibility to endotoxin shock.