Protection against concanavalin A-induced hepatocyte apoptosis by molsidomine is time-dependent

BACKGROUND: Viral hepatitis and autoimmune liver diseases cause hepatocyte apoptosis. Concanavalin A (Con A)-induced hepatitis resembles human viral hepatitis and autoimmune hepatitis. The role of nitric oxide (NO) in liver injury was controversial in different liver injury models. We hypothesize both endogenous and exogenous NO protect liver against Con A-induced liver injury. Molsidomine is metabolized into SIN-1 by the liver, and SIN-1 subsequently generates NO. So, molsidomine was used as a NO donor in this study. STUDY DESIGN: To study a protective role of endogenous NO in Con A-induced liver injury, mice were pretreated with a specific inducible nitric oxide synthase (iNOS) inhibitor, L-N(6)-(1-iminoethyl)-lysine (L-NIL), before Con A challenge. To study a time-dependent protection against Con A-induced liver injury, animals were either given molsidomine, a NO donor, before or after Con A administration. Serum alanine aminotranferase (ALT) was analyzed. Liver samples were subjected to DNA fragmentation assay, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling stain, Western blot analysis, and caspase activity assays. RESULTS: Animals pretreated with L-NIL had significantly increased serum ALT levels compared with those challenged with Con A alone; but pretreatment with molsidomine dramatically decreased ALT levels in L-NIL-pretreated animals or in animals that received Con A alone. Administration of molsidomine 30 minutes before or 1, 2, and 3 hours after Con A injection significantly reduced serum ALT levels and attenuated hepatocyte apoptosis from caspase inactivation. The ALT reduction was associated with inhibition of both caspase-3 and caspase-8 activation and reduction of hepatocyte apoptosis. CONCLUSIONS: Endogenous NO plays an important protective role against Con A-induced liver injury by reducing hepatocyte apoptosis. Administration of a NO donor early after Con A injection protects the liver from injury. This is the first study demonstrating a time-dependent inhibition of liver injury induced by Con A administration.     

Ketamine inhibits endotoxin-induced shock in rats

BACKGROUND: Cytokines and nitric oxide are believed to participate importantly in the pathogenesis of endotoxin-induced shock. Several investigators have documented that ketamine attenuates production of cytokines and nitric oxide in endotoxemia, but little is known concerning hemodynamic effects of the drug in this state. The objective of the current study was to assess the potential modifying effects of ketamine in endotoxemia. METHODS: The authors randomly assigned 40 rats to one of four equal groups: endotoxin alone, receiving Escherichia coli endotoxin (15 mg/kg, administered intravenously); saline control, receiving saline only; ketamine alone, receiving ketamine (10 mg x kg(-1) x h(-1), administered intravenously); pretreatment, with ketamine administration initiated before the endotoxin exposure; and posttreatment, with ketamine initiated 2 h after endotoxin. During the 5 h after endotoxin injection, hemodynamics, acid-base status, and plasma concentrations of tumor necrosis factor alpha and interleukin 6 were assessed in each group. RESULTS: Endotoxin injection produced progressive hypotension, metabolic acidosis, and a large increase in the plasma cytokine concentrations. This hemodynamic and cytokine responses to endotoxin were completely abolished in the pretreatment group and modestly suppressed in the posttreatment group. in the absence of endotoxin, ketamine did not modify these responses. CONCLUSION: Ketamine administration inhibited hypotension, metabolic acidosis, and cytokine responses in rats injected with endotoxin. The results suggest that judicious use of ketamine as an anesthetic agent may offer advantages in endotoxemia.     

Immunoglobulin Enriched Colostral Milk Reduces Gut-Derived Endotoxemia in a Rat Hemorrhage Model

Background: Several studies indicate that a breakdown of mucosal barrier is often a major cause of endotoxemia and septic complications after hemorrhagic/traumatic insults. The aim of this study was to investigate, whether enteral administration of an immunoglobulin enriched colostral milk preparation (ICM) is able to affect endotoxemia as well as survival in a hemorrhagic shock model in rats. Materials and Methods: Rats were orally pre-treated with either 5 ml of 0.9% saline (CON) or ICM (3 g/kg body weight) once a day for 5 days (ICM). Laboratory control animals were not treated (LAB-CON). On day 6, intestinal endotoxin contents were assessed. In a separate set of animals treated similarly, hemorrhage was induced on the 6th day by bleeding the animals to a mean arterial pressure of 30-35 mm Hg for 3 h followed by resuscitation over 1 h. Results: Pre-treatment with ICM significantly reduced intraluminal endotoxin contents in the duodenum when compared with CON (0.43 - 0.27 vs.. 1.03 - 0.67 EU/mg contents; p = 0.03). Hemorrhage for 3 h resulted in a significant rise in plasma endotoxin concentrations in CON animals compared with LAB-CON (0.30 - 0.20 vs. 0.06 - 0.04 EU/ml). ICM pre-treatment attenuated plasma endotoxin levels after hemorrhage(0.11 - 0.12 EU/ml). The 6-day-survival rate after hemorrhage tended to be higher in the ICM pre-treated animals when compared with CON (66.7% vs. 40%). Conclusion: A passive immunization of the gut together with the reduction of the intraluminal endotoxin contents by enteral administration of immunoglobulin-enriched preparations might prove to be a prophylactic approach towards preventing gut-derived endotoxemia after hemorrhagic/traumatic insults.     

Ketamine Inhibits Endotoxin-induced Shock in Rats

Background: Cytokines and nitric oxide are believed to participate importantly in the pathogenesis of endotoxin-induced shock. Several investigators have documented that ketamine attenuates production of cytokines and nitric oxide in endotoxemia, but little is known concerning hemodynamic effects of the drug in this state. The objective of the current study was to assess the potential modifying effects of ketamine in endotoxemia.

Methods: The authors randomly assigned 40 rats to one of four equal groups: endotoxin alone, receiving Escherichia coli endotoxin (15 mg/kg, administered intravenously); saline control, receiving saline only; ketamine alone, receiving ketamine (10 mg [middle dot] kg-1 [middle dot] h-1, administered intravenously); pretreatment, with ketamine administration initiated before the endotoxin exposure; and posttreatment, with ketamine initiated 2 h after endotoxin. During the 5 h after endotoxin injection, hemodynamics, acid-base status, and plasma concentrations of tumor necrosis factor [alpha] and interleukin 6 were assessed in each group.

Results: Endotoxin injection produced progressive hypotension, metabolic acidosis, and a large increase in the plasma cytokine concentrations. This hemodynamic and cytokine responses to endotoxin were completely abolished in the pretreatment group and modestly suppressed in the posttreatment group. In the absence of endotoxin, ketamine did not modify these responses.     

ONO-1714, a nitric oxide synthase inhibitor, attenuates endotoxin-induced acute lung injury in rabbits

Overproduction of nitric oxide by inducible nitric oxide synthase (iNOS) expressed in the lung is thought to play a crucial role in the pathogenesis of endotoxin-induced acute lung injury (ALI). In this two-part study, we determined whether ONO-1714, a new selective iNOS inhibitor, attenuates endotoxin-induced ALI in rabbits. For Part I of the study, a control group received IV saline and ALI was induced by IV infusion of endotoxin 5 mg/kg over 30 min in 4 groups. Three groups received either 0.1, 0.03, or 0.01 mg/kg of ONO-1714 10 min before the start of endotoxin and the fourth group received saline. For Part II of the study, ALI was induced by endotoxin infusion in all 6 groups. One group was treated with saline. The other 5 groups received ONO-1714 0.1 mg/kg at various timings (10 min before or 1, 2, 3, or 4 h after ALI induction). The lungs were mechanically ventilated with 40% oxygen for 6 h after induction of ALI. In Part I, pretreatment with 0.1 mg/kg ONO-1714 mitigated endotoxin-induced ALI. In Part II, early posttreatment (within 2 h after the insult) with ONO-1714 was as effective as pretreatment in improving oxygenation, lung mechanics, lung leukosequestration, pulmonary edema, and histological change. However, lung damage was not improved in rabbits receiving the drug 3 or 4 h after endotoxin. These data suggest that the current study is a basis for future clinical trials to elucidate whether ONO-1714 can be a promising therapeutic approach in patients with acute respiratory distress syndrome induced by endotoxin/sepsis. IMPLICATIONS: An excess of nitric oxide is thought to play a crucial role in the pathogenesis of acute organ injury in endotoxemia. Early posttreatment with ONO-1714, a nitric oxide synthase inhibitor, attenuated physiological, biochemical, and pathological changes in endotoxin-induced acute lung injury in rabbits.     

Intrarenal Administration of Molsidomine, a Molecule Releasing Nitric Oxide, Reduces Renal Ischemia-Reperfusion Injury in Rats

Ischemia reperfusion (I-R)-induced renal damage is reduced by systemic administration of the NO-dependent vasodilator molsidomine. The aim of this study was to estimate the effect of direct intrarenal molsidomine administration on renal dysfunction and inflammatory reaction after experimental I-R in rats, in order to assess only renal NO effects and to obviate its systemic hemodynamic action. Ischemia was induced by renal pedicle ligation (60 min) followed by reperfusion and contralateral nephrectomy. Molsidomine (4 mg/kg) was infused into the renal artery 15 min before reperfusion and its effects were compared with those of the NO-independent vasodilator hydralazine (2 mg/kg). Survival rates after 7 days were 100% in the sham-operated group and 75% in the I-R rats. Molsidomine treatment almost completely prevented the I-R-induced renal dysfunction, and survival reached 100%. Molsidomine prevented an I-R-induced increase in superoxide anion and reduced plasma levels of pro-inflammatory cytokines (TNF-alpha, IL-1beta and IFN-gamma), whereas it enhanced anti-inflammatory cytokines (IL-6 and IL-10). Inflammatory cell infiltration and cell-adhesion molecules (ICAM-1, PECAM-1, VCAM-1 and P-selectin) were lower in the molsidomine-treated kidneys than in the untreated animals. All these protective effects were not observed after hydralazine administration. In conclusion, intrarenal administration of molsidomine before reperfusion improved renal function and decreased inflammatory responses after I-R.     

Effects of the nitric oxide donor molsidomine on the early stages of liver damage in rats with bile duct ligation: a biochemical and immunohistochemical approach

This study aimed to evaluate the effects of the nitric oxide donor molsidomine on the early stages of liver damage and biochemical changes in rats with bile duct ligation (BDL). Forty prepubertal male Sprague-Dawley rats weighing 125-140 g were studied. Group 1 rats (sham-control, n = 10) were not subjected to any surgical manipulation. Group 2 rats (BDL/untreated, n = 10) were subjected to BDL but no drug was administered. Group 3 rats (BDL/L-NAME, n = 10) received a daily dose of N(G)-nitro-L-arginine methyl ester (L-NAME) intraperitoneally for 7 days after BDL. Group 4 rats (BDL/molsidomine, n = 10) received a daily dose of molsidomine by gastric tube for 7 days after BDL. After 1 week, biochemical and histological evaluations were performed and the liver hydroxyproline content was measured. Serum bilirubin and liver enzymes were significantly increased in the BDL/untreated, BDL/L-NAME and BDL/molsidomine groups in comparison with the sham-control group 1 week after BDL. However, the liver enzymes were significantly decreased in the BDL/molsidomine group in comparison with the BDL/untreated and BDL/L-NAME groups. In the BDL/L-NAME group, proliferation of portal and periportal biliary ductules with disorganization of the hepatocyte plates, dilated portal spaces and areas of polymorphonuclear leukocyte infiltration, fibrosis and hepatocyte necrosis were observed. In the BDL/molsidomine group, polymorphonuclear leukocyte infiltration, hepatocyte necrosis and fibrosis were rarely seen. The hydroxyproline content in the liver was increased 1 week after obstruction in the BDL/untreated and BDL/L-NAME groups when compared to BDL/molsidomine group. Collagen type-IV expression was not observed in the BDL/molsidomine group in contrast to the BDL/untreated and BDL/L-NAME groups. In conclusion, during 1 week of treatment, the nitric oxide donor molsidomine improved hepatic fibrosis in the hepatic parenchyma and did not affect serum bilirubin values, but positively affected the serum aspartate aminotransferase and alanine aminotransferase values.     

极化液对内毒素血症大鼠肝损伤的影响

目的研究葡萄糖-胰岛素-钾(极化液,GIK)对内毒素血症大鼠肝损伤的影响。方法雄性SD大鼠60只,体重200~250g,随机分为三组:对照组,脂多糖组(LPS组,LPS 8mg/kg),GIK组(LPS 8mg/kg+GIK 4ml·kg~(-1)·h~(-1))。采用全自动生化仪检测腹腔注射LPS后3d和5d大鼠血清丙氨酸氨基转移酶(ALT)及天门冬氨酸氨基转移酶(AST)含量,ELISA法检测三组大鼠肝组织匀浆TNF-α含量,并行HE染色观察肝组织病理变化,TUNEL免疫荧光检测肝实质细胞凋亡情况。结果与注射后3d比较,注射后5dLPS组大鼠血清ALT、AST、肝组织匀浆TNF-α含量明显升高,而GIK组大鼠血清ALT、AST、肝组织匀浆TNF-α含量明显下降(P0.05)。与对照组比较,注射后3dLPS组和GIK组大鼠血清ALT、AST、注射后5dLPS组大鼠血清ALT、AST明显升高(P0.05),注射后3、5dLPS组和GIK组大鼠肝组织匀浆TNF-α含量、肝损伤等级评分、肝细胞凋亡指数明显升高(P0.05)。与LPS组比较,注射后3dGIK组大鼠肝组织匀浆TNF-α含量、肝细胞凋亡指数明显降低(P0.05),注射后5dGIK组大鼠血清ALT、AST、肝组织匀浆TNF-α含量、肝损伤等级评分、肝细胞凋亡指数明显降低(P0.05)。结论腹腔注射LPS可引起大鼠肝损伤,导致肝功能改变及肝细胞破坏;GIK可减轻LPS诱导的大鼠肝损伤。     

Beneficial effects of hypertonic saline/dextran on early survival in porcine endotoxin shock

BACKGROUND: Hypertonic saline/dextran (HSD) has been shown to have beneficial effects in haemorrhagic shock. These effects, with improved haemodynamics and organ perfusion, would in theory also be of benefit in septic shock. However, this is less studied. We have therefore further evaluated the effect of additional treatment with HSD in a porcine endotoxin shock model. METHODS: Sixteen anaesthetized pigs were used. A continuous infusion of endotoxin (LPS EC) was increased stepwise during 30 min to a rate of 5 microg/kg/h. The infusion was discontinued after 3 h and the animals were observed for another 2 h. The animals received continuous basal fluid resuscitation with isotonic Ringer's glucose 2.5% at a rate of 20 ml/kg/h throughout the experiment. After 1 h of endotoxin infusion, the animals were randomized to additional treatment with HSD, 4 ml/kg over 5 min, or the same volume of isotonic saline. Every 30 min, haemodynamics and mixed venous saturation (SvO2) were measured via a pulmonary artery catheter. Regional blood flow rates were measured continuously by perivascular ultrasonic flow probes. The metabolic response was measured by arterial blood gas analysis. RESULTS: The endotoxin put all animals into a progressive hypodynamic circulatory shock during the experiment. Treatment with HSD improved survival rate to 8/8 compared with controls 3/8. There was a transient circulatory recovery with improved central and regional haemodynamics, accompanied by stabilized metabolic response. CONCLUSION: Treatment with additional HSD improves survival in an early phase of endotoxin shock. Generally improved haemodynamics and oxygenation of peripheral tissues are suggested as possible mechanisms.     

Effect of ONO1714, a specific inducible nitric oxide synthase inhibitor, on lung lymph filtration and gas exchange during endotoxemia in unanesthetized sheep

BACKGROUND: The effect of nitric oxide synthase inhibitor on acute lung injury remains controversial. The current study was designed to examine effects of a newly synthesized and selective inducible nitric oxide synthase inhibitor, ONO1714, on endotoxin-induced lung injury in unanesthetized sheep. METHODS: Thirteen unanesthetized sheep chronically instrumented with a lung lymph fistula and vascular catheters for monitoring were prepared. Animals were randomly allocated into two experimental groups. In experiment 1, sheep (n = 6) were infused only with endotoxin (1 microg/kg) for 30 min. In experiment 2, sheep (n = 7) were pretreated with ONO1714 (0.1 mg/kg) before 30 min of endotoxin administration, and the endotoxin was infused in the same manner as in experiment 1. Mean pulmonary arterial pressure, left atrial pressure, systemic arterial pressure, and lung lymph flow were measured. Observation was continued over 5 h after endotoxin administration. RESULTS: ONO1714 did not cause any pulmonary hemodynamic changes at baseline or exert any influences on transient pulmonary hypertension and increased pulmonary vascular resistance during endotoxemia. However, inducible nitric oxide synthase inhibition with ONO1714 significantly reduced lung lymph filtration and improved abnormal oxygenation during endotoxemia. In addition, increased nitrate-nitrite in plasma and lung lymph in response to endotoxin was prevented by treatment with ONO1714. CONCLUSIONS: These findings suggest that nitric oxide release by the inducible nitric oxide synthase pathway partially contributes to the increased permeability of pulmonary edema and decreased oxygenation during endotoxemia in sheep.     

Effects of selective nitric oxide synthase inhibition in hyperdynamic endotoxemia in dogs.

OBJECTIVES: Our aims were to investigate the systemic hemodynamic effects of constitutive endothelial nitric oxide synthase (eNOS) and inducible NOS (iNOS) inhibitors in hyperdynamic endotoxemia. PATIENTS AND METHODS: Group 1 comprised sham-operated controls, while in group 2, 3 and 4, a hyperdynamic circulatory reaction was elicited by a 2-hour infusion of Escherichia coli endotoxin (ETX) in a dose of 5.3 microg/kg. The animals in group 3 were treated with 12. 5 mg/kg nonselective NOS inhibitor N-omega-nitro-L-arginine methyl ester (L-NAME), and those in group 4 with 2 mg/kg of the specific iNOS inhibitor S-methyl-isothiourea (SMT). Mean arterial pressure (MAP), cardiac output (CO) and myocardial contractility (MC) were measured, and total peripheral resistance (TPR) was calculated. The eNOS and iNOS activities were determined in myocardial biopsy samples taken after 8 h of endotoxemia. RESULTS: ETX induced significant decreases in TPR and MAP, a transient myocardial depression, and increased the myocardial eNOS and iNOS activities. L-NAME decreased the activities of both isoenzymes, increased MC but induced a fall in CO. SMT inhibited iNOS by 60%, without influencing the eNOS activity, increased MAP and contractility in the early phase of endotoxemia, and induced only a slight decrease in CO. CONCLUSIONS: Nonselective NOS inhibition restores the arterial pressure and exerts a positive inotropic effect, but decreases CO. SMT selectively decreases the iNOS activation without disturbing the vasoregulatory function of the eNOS-derived nitric oxide in hyperdynamic endotoxemia in the dog.     

Sevoflurane pretreatment inhibits endotoxin-induced shock in rats

We examined the effects of sevoflurane pretreatment on mortality and inflammatory responses during endotoxin-induced shock. Rats were allocated randomly to 1 of 4 groups (n = 12 per group): an endotoxemia group, receiving IV Escherichia coli endotoxin (15 mg/kg over 2 min); a saline control group, receiving 0.9% saline (1.0 mL/kg); a sevoflurane-only group, receiving 2.4% sevoflurane for 30 min immediately before injection of 0.9% saline; and a sevoflurane pretreatment group, receiving 2.4% sevoflurane for 30 min immediately before injection of endotoxin. Hemodynamic variables, arterial blood gases, and plasma concentrations of tumor necrosis factor-alpha and interleukin-6 were measured. The 8-h mortality rate was determined. Systolic arterial blood pressure and acid-base balance improved with sevoflurane pretreatment before induction of endotoxemia. Mortality rates 8 h after endotoxin injection were 83%, 8%, 0%, and 25% for the endotoxemia, saline control, sevoflurane-only, and sevoflurane pretreatment groups, respectively. Plasma cytokine concentrations were significantly larger in the endotoxemia group than in the other groups. Sevoflurane pretreatment inhibited inflammatory responses and decreased mortality in rats exposed to endotoxin. IMPLICATIONS: Sevoflurane pretreatment decreased mortality rate, severity of hypotension, and acidosis, and inhibited cytokine responses in rats injected with endotoxin, suggesting that sevoflurane may be an anesthetic of choice in endotoxemic states.     

Continuously infused methylene blue modulates the early cardiopulmonary response to endotoxin in awake sheep

BACKGROUND: In endotoxemia and septic shock, enhanced generation of endogenous nitric oxide (NO) contributes to myocardial depression, hypotension, and derangement of gas exchange. We hypothesized that continuous infusion of methylene blue (MB), an inhibitor of the NO pathway, would counteract these effects in endotoxemic sheep. METHODS: Twenty-one sheep were anesthetized and instrumented for a chronic study with vascular catheters. On the day of the experiment, 18 conscious animals randomly received either an intravenous injection of MB 10 mg x kg(-1) or isotonic saline. Thirty minutes later, sheep received a 20-min intravenous infusion of Escherichia coli endotoxin 1 microg x kg(-1) and either an intravenous infusion of MB 2.5 mg x kg(-1) x h(-1) or isotonic saline, respectively, for 5 h. In addition, 3 animals were exposed to the same dose of MB alone. RESULTS: MB reduced the early endotoxin-induced declines in stroke volume, left ventricular stroke work and cardiac indices, and prevented mean arterial pressure from falling. Moreover, MB ameliorated the increases in pulmonary arterial pressure and pulmonary vascular resistance index. In addition, MB reduced the increments in venous admixture and AaPO2, decreased the falls in PaO2, SaO2, and oxygen delivery, and maintained oxygen consumption. MB also prevented the rises in body temperature and plasma nitrites and nitrates, and delayed the elevation of plasma lactate. When given alone to healthy sheep, MB transiently reduced plasma lactate and PaO2, and increased AaPO2. CONCLUSION: In ovine endotoxemia, continuously infused MB counteracts the early myocardial dysfunction and derangement of hemodynamics and gas exchange.     

Hemodynamic and metabolic manifestations of acute endotoxin infusion in pigs with and without the malignant hyperthermia mutation.

BACKGROUND: The hypermetabolic state induced by acute endotoxemia and malignant hyperthermia (MH) may be indistinguishable. The aims of this study were (1) to investigate the differences between MH and sepsis, (2) to determine whether acute endotoxemia can trigger MH, and (3) to establish the effects of dantrolene in these two disorders. METHODS: Three groups of swine were studied. All pigs were invasively monitored and initially anesthetized with nontriggering agents. A placebo MH-susceptible group (n = 5) received normal saline whereas the endotoxin groups (MH-susceptible, n = 6; MH-negative, n = 4) received intravenous endotoxin (250 microg/kg total) during 2.5 h. Halothane (1.5%) and succinylcholine (2-4 mg/kg) were then administered, followed by two doses of dantrolene (4 mg/kg total). RESULTS: Endotoxin infusion resulted in pulmonary hypertension and systemic hypotension in pigs with and without the MH mutation, but did not trigger MH. Halothane and succinylcholine triggered MH, evidenced by a markedly higher oxygen consumption in the MH-susceptible pigs that received endotoxin (325+/-196 ml/min) and those that did not (374+/-110 ml/min) compared to the MH-negative pigs (69+/-15 ml/min, P<0.0009), as well as muscular rigidity in the susceptible animals. Dantrolene reversed these changes. Three of the six MH-susceptible pigs that received endotoxin died; two died soon after triggering and one after dantrolene administration. In contrast, none of the MH-negative pigs or the MH-susceptible pigs that did not receive endotoxin died (0 of 9 vs. 3 of 6, P = 0.044). CONCLUSION: Endotoxemia does not trigger MH, but may worsen outcome if it occurs.     

Effects of vitamin A on endotoxaemia in rats.

OBJECTIVES: To find out if survival after peritonitis induced by caecal puncture and injection of endotoxin is correlated with serum endotoxin concentrations in rats; whether this study could be carried out by studying the effects of vitamin A in rats with peritonitis; and if it was possible to differentiate between local and systemic effects of vitamin A on endotoxaemia in rats. DESIGN: Prospective randomised study. MATERIAL: Sixty adult male Sprague-Dawley rats. INTERVENTIONS: Rats were kept on a diet containing no vitamin A for six days; 30 were given vitamin A 1,380 IU/kg/day intramuscularly and 30 were given peanut oil. Peritonitis was then induced in 16 rats by caecal puncture (treated n = 10, untreated n = 6) and the remainder received intraperitoneal injections of either 0.5 mg/kg endotoxin, or 2.0 mg/kg endotoxin. MAIN OUTCOME MEASURES: Plasma concentrations of vitamin A, vitamin E, and serum concentrations of endotoxin, estimation of erythrocyte volume fraction and leucocyte particle concentrations, and survival. RESULTS: Rats that were given 2 mg of endotoxin had higher mortality and did generally less well than others. Serum endotoxin concentrations were lower in those groups that had been pretreated with vitamin A. No animal developed vitamin A deficiency and there were no differences in erythrocyte volume fraction or leucocyte particle concentration between those that did and did not receive vitamin A. CONCLUSION: Vitamin A lowered the concentration of endotoxin in the circulation, it has a central function in the host's defence against endotoxin, and the experimental model seems suitable for the study of the effect of vitamin A or endotoxemia and peritonitis.     

Hemodynamic and Metabolic Manifestations of Acute Endotoxin Infusion in Pigs with and without the Malignant Hyperthermia Mutation

Background: The hypermetabolic state induced by acute endotoxemia and malignant hyperthermia (MH) may be indistinguishable. The aims of this study were (1) to investigate the differences between MH and sepsis, (2) to determine whether acute endotoxemia can trigger MH, and (3) to establish the effects of dantrolene in these two disorders.

Methods: Three groups of swine were studied. All pigs were invasively monitored and initially anesthetized with nontriggering agents. A placebo MH-susceptible group (n = 5) received normal saline whereas the endotoxin groups (MH-susceptible, n = 6; MH-negative, n = 4) received intravenous endotoxin (250 [mu]g/kg total) during 2.5 h. Halothane (1.5%) and succinylcholine (2-4 mg/kg) were then administered, followed by two doses of dantrolene (4 mg/kg total).

Results: Endotoxin infusion resulted in pulmonary hypertension and systemic hypotension in pigs with and without the MH mutation, but did not trigger MH. Halothane and succinylcholine triggered MH, evidenced by a markedly higher oxygen consumption in the MH-susceptible pigs that received endotoxin (325 +/- 196 ml/min) and those that did not (374 +/- 110 ml/min) compared to the MH-negative pigs (69 +/- 15 ml/min, P < 0.0009), as well as muscular rigidity in the susceptible animals. Dantrolene reversed these changes. Three of the six MH-susceptible pigs that received endotoxin died; two died soon after triggering and one after dantrolene administration. In contrast, none of the MH-negative pigs or the MH-susceptible pigs that did not receive endotoxin died (0 of 9 vs. 3 of 6, P = 0.044).     

The dose-related effects of ketamine on mortality and cytokine responses to endotoxin-induced shock in rats

In our previous study, ketamine administration was found to inhibit hypotension, metabolic acidosis, and cytokine responses in endotoxemia. However, only a few studies have indicated whether ketamine has the dose-related beneficial effects after endotoxin injection. Our objective was to clarify the dose-related effects of ketamine on mortality and cytokine responses to endotoxemia in rats. Sixty-five rats were divided at random among five equal groups: Group C was given saline alone. Group E was given endotoxin alone (Escherichia coli endotoxin; 10 mg/kg, IV). Group L received a a low dose of ketamine (5 mg.kg(-1).h(-1), IV), Group M a medium dose of ketamine (10 mg.kg(-1).h(-1), IV), and Group H a high dose of ketamine (20 mg.kg(-1).h(-1), IV), all exposure to endotoxin. After endotoxin injection, hemodynamics, acid-base status, mortality rate, and plasma concentrations of tumor necrosis factor alpha and interleukin 6 were assessed for each of the five groups. Endotoxin injection produced progressive hypotension, metabolic acidosis, and a large increase in plasma cytokine concentrations. Mortality rates 8 h after endotoxin injection were 0% for group C, 92% for group E, 48% for group L, 0% for group M, and 32% for group H. Ketamine administration thus clearly had a beneficial effect on mortality rates, with that for group M lower than for groups L and H (P < 0.05). The cytokine responses to endotoxin were somewhat suppressed in group M but not in group L. Ketamine administration dose-independently inhibited hypotension, metabolic acidosis, and cytokine responses in rats injected with endotoxin.     

Effect of ONO1714, a Specific Inducible Nitric Oxide Synthase Inhibitor, on Lung Lymph Filtration and Gas Exchange during Endotoxemia in Unanesthetized Sheep

Background: The effect of nitric oxide synthase inhibitor on acute lung injury remains controversial. The current study was designed to examine effects of a newly synthesized and selective inducible nitric oxide synthase inhibitor, ONO1714, on endotoxin-induced lung injury in unanesthetized sheep.

Methods: Thirteen unanesthetized sheep chronically instrumented with a lung lymph fistula and vascular catheters for monitoring were prepared. Animals were randomly allocated into two experimental groups. In experiment 1, sheep (n = 6) were infused only with endotoxin (1 [mu]g/kg) for 30 min. In experiment 2, sheep (n = 7) were pretreated with ONO1714 (0.1 mg/kg) before 30 min of endotoxin administration, and the endotoxin was infused in the same manner as in experiment 1. Mean pulmonary arterial pressure, left atrial pressure, systemic arterial pressure, and lung lymph flow were measured. Observation was continued over 5 h after endotoxin administration.

Results: ONO1714 did not cause any pulmonary hemodynamic changes at baseline or exert any influences on transient pulmonary hypertension and increased pulmonary vascular resistance during endotoxemia. However, inducible nitric oxide synthase inhibition with ONO1714 significantly reduced lung lymph filtration and improved abnormal oxygenation during endotoxemia. In addition, increased nitrate-nitrite in plasma and lung lymph in response to endotoxin was prevented by treatment with ONO1714.     

大承气汤对内毒素血症小鼠血清一氧化氮浓度的影响

目的：观察大承气汤（ＤＤ）对内毒素血症小鼠血清一氧化氮（ＮＯ）浓度的影响。方法：通过腹腔注射大肠杆菌内毒素对小鼠进行内毒素血症造模,治疗组同时经口投与ＤＤ：采用Ｇｒｉｅｓｓ试剂比色法间接测定血清ＮＯ浓度。结果：模型组小鼠血清ＮＯ浓度明显高于正常组,而ＤＤ治疗组则明显低于模型组。结论：ＤＤ对内毒素血症小鼠一氧化氮浓度的升高有明显的降低作用。     

Increased lethality of endotoxemia in murine frostbite

Because frostbite (FB) is associated with increased intravascular coagulability, it is reasonable to assume that endotoxin, by enhancing platelet aggregation, will adversely affect FB. Swiss mice (25 +/- 2 g) were anesthetized, and the tails of the animals totally immersed in a freezing solution of equal volumes of ethylene glycol and water (-18 C) for 8 min. The tails were then thawed at room temperature (24 C). Half an hour after removal from the freezing solution, the animals were given either (Group A) 0.1 cc saline I.P. or (Group B) 0.1 mg E. coli endotoxin (055:B5; 1/3 LD50 dose) in 0.1 cc saline IP. A third group (Group C), was given the same dose of endotoxin but was not subjected to frostbite. Survivals in each group at 2 weeks were as follows: (A) 14/14 (100%), (B) 4/20 (20%), (C) 13/14 (93%). Using Fisher's exact test, A versus B P less than .001; B versus C P less than .001; A versus C NS. The data presented here emphasize the increased lethality of endotoxemia in murine FB.