Endotoxin Shock In Rats Research Articles

Anti-Inflammatory Effects of Shenfu Injection against Acute Lung Injury through Inhibiting HMGB1-NF-κB Pathway in a Rat Model of Endotoxin Shock.

Shenfu injection (SFI), a Chinese herbal medicine with substances extracted from Ginseng Radix et Rhizoma Rubra and Aconiti Lateralis Radix Praeparata, is widely used as an anti-inflammatory reagent to treat endotoxin shock in China. However, the mechanism of SFI in endotoxin shock remains to be illuminated. High mobility group box 1 (HMGB1), a vital inflammatory factor in the late stage of endotoxin shock, may stimulate multiple signalling cascades, including κB (NF-κB), a nuclear transcription factor, as well as tumour necrosis factor (TNF)-α and interleukin (IL)-1β, among others in the overexpression of downstream proinflammatory cytokines. An investigation into the effects of SFI on the inhibition of the HMGB1-NF-κB pathway revealed the contribution of SFI to acute lung injury (ALI) in a rat model of endotoxin shock. To assess the anti-inflammatory activity of SFI, 5 ml/kg, 10 ml/kg, or 15 ml/kg of SFI was administered to different groups of rats following an injection of LPS, and the mean arterial pressure (MAP) at 5 h and the survival rate at 72 h were measured. 24 h after LPS injection, we observed pathological changes in the lung tissue and measured the mRNA expression, production, translocation, and secretion of HMGB1, as well as the expression of the NF-κB signal pathway-related proteins inhibitor of NF-κB (IκB)-α, P50, and P65. We also evaluated the regulation of SFI on the secretion of inflammatory factors including interleukin-1 beta (IL-1β) and TNF-α. SFI effectively prevented the drop in MAP, relieved lung tissue damage, and increased the survival rate in the endotoxin shock model in dose-dependent manner. SFI inhibited the transcription, expression, translocation, and secretion of HMGB1, increased the expression of toll-like receptor (TLR4), increased the production of IκB-α, and decreased the levels of P65, P50, and TNF-α in the lung tissue of endotoxin shock rats in a dose-dependent manner. Furthermore, SFI decreased the secretion of proinflammatory cytokines TNF-α and IL-1β. In summary, SFI improves the survival rate of endotoxin shock, perhaps through inhibiting the HMGB1-NF-κB pathway and thus preventing cytokine storm.

Lipopolysaccharide inhibits hepatic gluconeogenesis in rats: The role of immune cells.

Aims/IntroductionBacterial septicemia has diverse clinical symptoms including severe hypoglycemia. However, sepsis‐induced hypoglycemia has not yet been examined in detail. The aim of the present study was to investigate the mechanisms underlying hypoglycemia in sepsis.Materials and MethodsWe induced endotoxin shock in rats using lipopolysaccharide (LPS). After an intraperitoneal injection of LPS, we measured gluconeogenesis using the pyruvate tolerance test. The effects of LPS on glucose metabolism were investigated in perfused livers and isolated hepatocytes. Furthermore, its effects on the production of inflammatory cytokines were examined in isolated splenocytes. The interaction between splenocytes and hepatocytes in response to LPS was investigated in vitro using a co‐culture of splenocytes and hepatocytes.ResultsIn the pyruvate tolerance test, the pretreatment with LPS decreased gluconeogenesis. The in vivo pretreatment of rats with LPS did not inhibit glucose production in perfused livers. The in vitro treatment of isolated hepatocytes with LPS did not decrease hepatic gluconeogenesis. Although LPS increased the production of inflammatory cytokines (tumor necrosis factor‐α, interferon‐γ, interleukin‐1β, interleukin‐6 and interleukin‐10) and nitric oxide in isolated splenocytes, only nitric oxide significantly inhibited gluconeogenesis in isolated hepatocytes. When splenocytes and hepatocytes were co‐cultured in medium containing LPS, the messenger ribonucleic acid expression of glucose‐6‐phosphatase in hepatocytes was suppressed.ConclusionsLPS reduced hepatic gluconeogenesis, at least in part, by stimulating the production of nitric oxide in splenocytes. This effect could contribute to the mechanisms responsible for septicemia‐induced hypoglycemia.

НАПРАВЛЕНИЯ ЗАЩИТНОГО ДЕЙСТВИЯ БИФЕРМЕНТНОГО КОНЪЮГАТА АНТИОКСИДАНТНЫХ БИОКАТАЛИЗАТОРОВ IN VIVO

Endotoxin shock in rats led to intravenous bolus of bacterial lipopolysaccharide (LPS) was accompanied by oxidative stress and increase of NO level in livers, lungs, kidneys, hearts of animals. The intravenous administration of bienzyme superoxide dismutase - chondroitin sulphate - catalase conjugate (SOD-CHS-CAT) showed its anti-endotoxemia action in rats at preventive (before initiation of injury) and therapeutic (after start of injury) application during cytokine phase of injury and influence on further stages of the damage. The injection of antioxidant SOD-CHS-CAT conjugate in a therapeutic regime did not demonstrate significant alterations of No level in livers, lungs, kidneys, hearts of rats (as compared to indices of the rat group with LpS action only) and displayed protective action on the kidney function by altered urea and creatinine in blood. The therapeutic effect of SOD-CHS-CAT was demonstrated by increase in organism viability. The effects of intravenous injection of SOD-CHS-CAT in a rat model of endotoxin shock showed a variety in the activity of this conjugate in addition to prevention of NO conversion in peroxynitrite upon interaction with O 2 superoxide radical. The results of accelerated normalization of arterial blood pressure and heart rate, a significant decrease in rat lethality because of using SOD-CHS-CAT conjugate indicate the importance of the determination of action mechanism of the cardiovascular injury models associated with other vasoactive agents besides NO. The further research of vascular damage pathogenesis and evaluation of its role in oxidative stress (time and place) are of paramount importance.

Dexmedetomidine renders a brain protection on hippocampal formation through inhibition of nNOS-NO signalling in endotoxin-induced shock rats

Background: Endotoxin shock (ES) and its severe complications, such as brain injury, remain a handicap clinically. Therefore, it is a clinical significance of developing a new drug to treat brain damage induced by ES.Aim: The present study aimed to observe the protective effect of dexmedetomidine (Dex) on hippocampal formation in endotoxin-induced shock rats and explore its possible mechanism.Methods: High and low doses of Dex were tail intravenously administered slowly. After a 5-minute interval, lipopolysaccharide was tail intravenous injected slowly to establish the ES rats. Six hours after Dex administration, these rats were immediately sacrificed. Then, the brain water content was determined. NO amounts in homogenate, cerebrospinal fluid and serum were detected by Griess Reagent assay. nNOS mRNA in hippocampal formation was measured by RT-PCR and nNOS protein was determined by Western blotting and immunohistochemistry.Results: ES rats showed that cerebral water contents were significantly increased, NO concentrations in brain tissues, serum and cerebrospinal fluid were each obviously raised and meanwhile expressions of nNOS mRNA and its protein in hippocampal formation were notably augmented. Treatment of these rats with Dex evidently decreased cerebral water contents, NO concentrations and nNOS mRNA and its protein expressions.Conclusion: These results demonstrated that Dex exerted a brain protection on hippocampal formation through inhibition of the nNOS-NO signalling in ES rats and Dex may have a favourably therapeutic value in treating brain damage in patients with endotoxin shock.

Relationship between iNOS expression and apoptosis in cerebral tissue, and the effect of Sini injection in endotoxin shock rats

ObjectiveTo investigate the dynamic changes and relationship of inducible nitric oxide synthase (iNOS) and apoptosis in endotoxin shock rats, as well as the effects of Sini injection. MethodsIn total, 102 Sprague-Dawley (SD) rats were randomly divided into a normal group (n=6, NG), sham operation group (n=24, OG), model group (n=24, MG), dexamethasone group (n=24, DG), and Sini group (n=24, SG). The endotoxin shock model was induced by an intravenous injection of lipopolysaccharide (LPS) (8 mg/kg). Rats in the OG, MG, DG, and SG groups were further divided into 4 groups: 1, 2, 3 and 6 h after shock groups (n=6 per group). iNOS expression was detected by immunohistochemistry. Terminal Deoxynucleotidyl Transferase Mediated Deoxyuridine Triphosphate-biotin Nick End Labeling (TUNEL) was employed to measure apoptosis. ResultsNo iNOS expression was found in the OG group. Compared with the OG group, iNOS expression in the MG group was markedly elevated, reached a peak at 1 h (P<0.01), decreased at 2 and 3 h, and rebounded at 6 h. Compared with the MG group, iNOS expression decreased significantly in both the DG (P<0.05) and SG (P<0.01) groups at 6 h. The number of apoptotic cells in the MG group was markedly increased than that in the NG and OG (P<0.01) groups, and reached a peak at 6 h. The number of apoptotic cells in the DG group at 1 and 2 h (P<0.01) and SG group at 2, 3 and 6 h (P<0.01) decreased when compared with the MG group. ConclusionSini injection can significantly inhibit NO generation, which decreases apoptosis and subsequently protects the brain from endotoxic shock.

Small volume resuscitation with 7.5% hypertonic saline, hydroxyethyl starch 130/0.4 solution and hypertonic sodium chloride hydroxyethyl starch 40 injection reduced lung injury in endotoxin shock rats: Comparison with saline

BackgroundThe aim of this study was to investigate the effects of small volume resuscitation with 7.5% hypertonic sodium chloride (HSS), hydroxyethyl starch 130/0.4 solution (HES), and hypertonic sodium chloride hydroxyethyl starch 40 injection (HSH) on endotoxin shock rat lung. MethodsThirty Sprague–Dawley (SD) rats were divided randomly into 5 groups ，Group C (negative control group), Group E (lipopolysaccharide, LPS +4 ml/kg saline), Group HSS (LPS +4 ml/kg HSS), Group HES (LPS +4 ml/kg HES) and Group HSH (LPS +4 ml/kg HSH). Endotoxin shock model of rat was produced by injection with LPS. Then small volume resuscitation with different fluids was implemented in each group, respectively. ResultsCompared to Group C(negative control group）, lung injury in the other four groups was increased. Compared to Group E(LPS +4 ml/kg normal saline), lung injury of Group HSS(LPS +4 ml/kg HSS), HES(LPS +4 ml/kg HES), and HSH (LPS +4 ml/kg HSH)was lessened. Compared to Group C, oxygenation index in Groups E, HSS, HES, and HSH were decreased (P < 0.01). Compared to Group E, oxygenation indexes in Groups HSS, HES, and HSH were significantly increased (P < 0.01). Data of tumor necrosis factor (TNF)-α of lung tissue had similar results. However, protein concentration of bronchoalveolar lavage fluid and hydrogen sulfide (H2S) concentration indicated contrary results. ConclusionSmall volume resuscitation with 7.5% hypertonic sodium chloride, hydroxyethyl starch 130/0.4 solution, and hypertonic sodium chloride hydroxyethyl starch 40 injection could lessen lung injury caused by lipopolysaccharide. And this effect had relation to change of TNF-α and H2S.

Study on Modified Shengmai Yin Injection for Prevention and Treatment of Brain Impairment in Endotoxin Shock Rats

To examine the effects of modified Shenmai Yin on invigorating vital energy, promoting blood flow, and protection against neural impairment in an endotoxin-induced shock rat model. Ninety-six SD rats were randomly divided into four groups: sham operation (saline 20 ml/kg), shock model (lipopolysaccharide, LPS, 8 mg/kg), Reformed Shengmai Yin (Pulse-activating Decoction) (LPS 8 mg/kg + reformed Shengmai Yin Injection 10 ml/kg), and dexamethasone (LPS 8 mg/kg + dexamethasone 5 mg/kg) groups. Each group was subdivided into 1 h, 2 h, 3 h, and 6 h time points for observation. The carotid artery was separated and connected with a biological functional system to monitor mean arterial pressure (MAP). Brain water levels, malonaldehyde (MDA) content, and superoxide dismutase (SOD) activity were also determined. In the shock model group, MAP was progressively decreased after injection of LPS, brain water and MDA contents were increased, brain SOD activity was decreased, and capillary vessel edema in brain tissue was also observed. All these parameters were improved significantly in both treatment groups, although the effects were more marked with Shengmai Yin than with dexamethasone. Modified Shengmai Yin exhibits strong anti-shock and neuroprotective effects against Endotoxin-induced shock.

Effect of human recombinant and bovine heat shock proteins (70 kDa) on hemodynamics and hemostasis in endotoxin shock in rats

Effect of human recombinant and bovine heat shock proteins (70 kDa) on hemodynamics and hemostasis in endotoxin shock in rats

Effects of Niupo Zhibao Pellet on high-mobility group box-1 protein expression in lung tissues of endotoxin shock rats

To observe the effects of Niupo Zhibao Pellet, a compound traditional Chinese herbal medicine, on high-mobility group box-1 protein (HMGB1) expression in lung tissues of rats with endotoxin shock. Thirty SPF Sprague-Dawley rats were randomly divided into control group, lipopolysaccharide (LPS) group and Niupo Zhibao Pellet group. Rats in Niupo Zhibao Pellet group were consecutively administered 7 days with 3 mL (1 g/L) Niupo Zhibao Pellet saline suspension every day by intragastric administration. Endotoxin shock was induced in rats of the LPS and Niupo Zhibao Pellet groups by intravenous injection of LPS (1.5 mg/kg) and intraperitoneal injection of D-galactosamine (100 mg/kg). Expression of HMGB1 in lung tissues was measured by immunohistochemical method with diaminobenzidine (DAB) coloration, fluorescein isothiocyanate (FITC) labeling, and by Western blotting. Expression of HMGB1 in lung tissues in the LPS group was increased and that in Niupo Zhibao Pellet group was higher than that in the LPS group and the control group. HMGB1 was presented in the cytoplasm of positive cells in the LPS group, but in the nucleus of positive cells in the Niupo Zhibao Pellet group. However, HMGB1 was little expressed in the lung tissues of normal rats. Niupo Zhibao Pellet can increase HMGB1 expression and locate HMGB1 in the nucleus but not the cytoplasm, which may be one of its mechanisms in reducing endotoxin shock.

Role of nuclear transcription factor-kappaB in endotoxin-induced shock in rats.

To investigate the role of NF-kappaB in endotoxic shock in rats, the model of endotoxin-shock rats was induced by intravenous infusion of lipopolysaccharide (LPS). 1 h, 2 h, 4 h and 6 h after LPS injection, the activation of NF-kappaB in blood mononuclear cells and the content of TNF-alpha and IL-6 in plasma was detected by enzyme-linked immunoadsordent assay (ELISA). The level of mean arterial pressure (MAP) and the histopathological changes of lung and liver were also observed. The activation of NF-kappaB in mononuclear cells increased 1 h after LPS injection and reached its peak 2 h after the injection, and its level was higher than that of normal group. The level of TNF-alpha was increased 1 h after the infusion and peaked 2 h after the injection, and its level was higher than that of normal group after LPS infusion. The content of IL-6 increased gradually with time, the IL-6 level was higher than that of normal group after LPS injection. MAP was decreased gradually with time and its level was lower than that of normal group after LPS injection. Pathological examination showed that endotoxic shock could cause pulmonary alveolar hemorrhage, edema and infiltration of inflammatory cell in lung tissue and congestion, edema, capillary dilation and inflammatory cell infiltration in liver tissue. It is concluded that NF-kappaB can up-regulate the expression of TNF-alpha and IL-6 in plasma and play an important role in endotoxin-induced shock in rats.

Effects of sarpogrelate, a 5-hydroxytriptamine 2A receptor antagonist on endotoxin shock in rats

It is known that 5-hydroxytriptamine (5-HT)2A receptors have some roles in vascular constriction, platelet aggregation, and superoxide production by neutrophils. 5-HT2A receptor antagonists are therefore expected to be effective for sepsis. The present study was performed to investigate the effects of sarpogrelate, a 5-HT2A receptor antagonist on endotoxin shock in rats.

Influence of electro-acupuncture of Neiguan on plasmic concentrations of NO and TNFalpha in endotoxin shock rats

To observe the effect of electro-acupuncture of Neiguan (PC 6) on mean systemic arterial blood pressure and plasmic concentrations of NO and TNFalpha in endotoxin shock rats. The model of endotoxin shock was induced by lipopolysaccharide (1.5 mg/kg i.v.) and D-galactosamine (100 mg/kg i.p.). Aminoguanidine (100 mg/kg i.p.) and electro-acupuncture of bilateral Neiguan (PC 6) were administered. A catheter was inserted into the right subclavian artery to record the change of blood pressure and the blood was abstracted out and centrifuged to determine the NO and TNFalpha concentrations. Electro-acupuncture of Neiguan (PC 6) retrieved the blood pressure and reduced the plasmic NO and TNFalpha concentrations. Electro-acupuncture of Neiguan (PC 6) expresses an anti-endotoxin shock effect by repressing the plasmic NO and TNFalpha concentrations smoothly and retrieving the blood pressure stably.

Depletion of liver glutathione potentiates the oxidative stress and decreases nitric oxide synthesis in a rat endotoxin shock model.

To verify the effects of liver glutathione depletion on redox status and nitric oxide system in a rat endotoxic shock model. Prospective, randomized, controlled study on rats. A cardiocirculatory research laboratory. A total of 28 Sprague-Dawley male rats (200-250 g body weight) were divided into four experimental groups. Arterial blood, liver, and lung samples were taken from each animal under sodium pentobarbital (40 mg/kg i.p.) anesthesia 4 hrs after lipopolysaccharide (LPS group: 5 mg/kg i.p.; n = 7) or vehicle (control group: isotonic NaCl sterile solution i.p.; n = 7) treatments. Phorone (250 mg/kg i.p.) was injected to deplete glutathione in another two experimental groups of rats 30 mins before LPS (phorone+LPS group; n = 7) or vehicle (phorone group; n = 7) treatments, and 4 hrs later the same samples as in LPS and control groups were taken under anesthesia. Compared with the control group, the LPS group presented higher plasma concentration of end products of nitric oxide metabolism nitrites/nitrates, higher lung activity of inducible nitric oxide synthase, and oxidative stress defined by increased plasma concentration of the lipid peroxides malonaldehyde and 4-hydroxynonenal, and decreased plasma total antioxidant capacity. Treatment with phorone depleted liver glutathione (80% to 90%). In the liver glutathione-depleted animals, the oxidative stress induced by LPS was potentiated and blunted the increases in inducible nitric oxide synthase and plasma nitrites/nitrates. These results show that depletion of the liver glutathione increases the oxidative stress and decreases nitric oxide synthesis of LPS-induced shock in rats.

PBN amplifies the production of the anti-inflammatory cytokine interleukin-10 in a rat endotoxin shock model: [formula omitted], H. Sang, G. L. Wallis, C. A. Stewart, Nai-ying Zheng, Guoying Bing, Free Radical Biology and Aging Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA

PBN amplifies the production of the anti-inflammatory cytokine interleukin-10 in a rat endotoxin shock model: [formula omitted], H. Sang, G. L. Wallis, C. A. Stewart, Nai-ying Zheng, Guoying Bing, Free Radical Biology and Aging Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA

Nitric oxide-independent activation of soluble guanylyl cyclase contributes to endotoxin shock in rats.

We investigated whether a complete inhibition of nitric oxide (NO) formation caused by bacterial endotoxin (lipopolysaccharide, LPS) in vivo prevents the hypotension and restores the vascular hyporeactivity to normal in vivo and ex vivo. The combination of dexamethasone (Dex; 3 mg/kg at 30 min before LPS) plus aminoguanidine (AG; 15 mg/kg at 2 h after LPS) inhibited the overproduction of nitrate (an indicator of NO) in the plasma and aortic smooth muscle and also prevented the development of the delayed hypotension in rats treated with LPS for 6 h. However, the vascular hyporeactivity to norepinephrine (NE) was only partially improved either in vivo or ex vivo in endotoxemic rats treated with Dex plus AG. Pretreatment of aortic rings with Nomega-nitro-L-arginine methyl ester (L-NAME) or 1H-[1,2, 4]oxidazolo[4,3-a]quinoxalin-1-one (ODQ) enhanced the contraction to NE in rings obtained from LPS-treated rats, but not in those from Dex plus AG-treated endotoxemic rats. Methylene blue, an inhibitor of soluble guanylyl cyclase (GC), completely restored contractions to NE and aortic cGMP levels to normal either in LPS-treated rats or in Dex plus AG-treated endotoxemic rats, whereas the cGMP level was partially inhibited by ODQ in LPS-treated rats only. These results suggest that non-NO mediator(s) also activates soluble GC during endotoxemia. Interestingly, we found that in the presence of tetraethylammonium (an inhibitor of K+ channels) plus L-NAME or charybdotoxin [a specific inhibitor of large-conductance Ca2+-activated K+ (KCa) channels] plus ODQ, the vascular hyporeactivity to NE in the LPS-treated group was also completely restored to normal. In addition, in the presence of L-NAME or ODQ, the vascular hyporeactivity to high K+ was abolished in rings from the LPS-treated group. These results suggest that LPS causes the production of other mediator(s), in addition to NO, which also stimulates soluble GC (i.e., increases the formation of cGMP) and then activates the large-conductance KCa channels in the vascular smooth muscle causing vascular hyporeactivity.

Soluble glucan protects against endotoxin shock in the rat: the role of the scavenger receptor.

Soluble carboxymethyl-b-1,3-glucan (CMG), a possible ligand for scavenger receptors, has macrophage-activating action but lacks the granulomatose inflammatory side effect: it is a promising immunomodulator that may mitigate the severity of sepsis. This motivated us to study in rats the effect of CMG (25 mg/kg), injected into the tail vein at 48 and 24 h prior to the administration of 5 mg/kg Escherichia coli 0127.B8 endotoxin on survival, hemodynamic condition, and, in vitro, on the chemiluminescence of PMNs and macrophages, and on macrophagal tumor necrosis factor (TNF) production. Acetylated low density lipoprotein (AcLDL) clearance in vivo and in vitro binding to macrophages was used to study scavenger receptor function. In the nonpretreated group 9 of 10 rats died during the first 24 h after endotoxin, but all CMG-pretreated rats survived. CMG-pretreatment prevented severe decreases in cardiac output and blood pressure after endotoxin. Chemiluminescence of macrophages and PMNs from CMG-pretreated rats was about two times less (p < .05) than that from nonpretreated ones; the endotoxin induced TNF production by macrophages also decreased. Pretreatment with CMG increased, but coinjection of CMG and AcLDL decreased the AcLDL clearance, while coinjection of endotoxin and AcLDL decreased the survival rate. In vitro AcLDL uptake by macrophages decreased after coinjection with CMG. Our results thus showed that CMG was protective in rat endotoxin shock, which seemed partly connected with enhancement of endotoxin clearance through scavenger receptors and to decreased TNF production.

Selective inhibition of cyclooxygenase-2 by NS-398 in endotoxin shock rats in vivo.

The role of cyclooxygenase (COX)-2 was examined using a rat endotoxin shock model and the potency and selectivity of NS-398, a COX-2 selective inhibitor in vitro, for COX-2 activity was examined in vivo. Male Wistar rats (weighing 140-180 g) were used. Lipopolysaccharide (LPS, 1 mg/kg, i.v.) was administered to rats (LPS-treated rats) and expression of COX-1 mRNA and COX-2 mRNA in the aorta and peripheral blood leukocytes was examined by RT-PCR. COX activity was assessed by measuring the plasma 6-keto prostaglandin (PG) F1 alpha, PGE2 and thromboxane (TX)B2 30s after administration of arachidonic acid (AA, 3 mg/kg, i.v.), NS-398 (0.3-100 mg/kg, p.o.) or indomethacin (0.3-3 mg/kg, p.o.) was administered 1 h before the AA injection. COX-2 mRNA was detectable in the aorta and peripheral blood leukocytes at least from 3 to 9 h after the LPS injection but not in non-LPS-treated rats. Plasma 6-keto PGF1 alpha, PGE2 and TXB2 levels after AA injection into LPS-treated rats were significantly enhanced compared to findings in non-LPS-treated rats. NS-398 showed significant inhibition of the increase in PGs in LPS-treated rats, the ED50 values being 0.35 mg/kg for 6-keto PGF1 alpha, 1.5 mg/kg for PGE2 and < 0.3 mg/kg for TXB2. NS-398 even at 100 mg/kg did not significantly suppress the increased PGs levels in non-LPS-treated rats. In contrast, indomethacin significantly inhibited plasma PGs levels after AA injection into LPS-treated rats and non-LPS-treated rats. The ED50 values in LPS-treated rats, determined by 6-keto PGF1 alpha, PGE2 and TXB2 production, were 1.0, 1.3 and 2.3 mg/kg and those in non-LPS-treated rats were 0.42, 0.24 and 0.93 mg/kg, respectively. In a rat endotoxin shock model, expression of COX-2 plays a role in an increase in COX activity. NS-398 showed preferential inhibitory effects on COX-2 activity in vivo. This approach is useful to directly analyze the inhibitory activity of NSAIDs for COX-1 and COX-2 in vivo.

Effects of phentolamine or yohimbine on naloxone's actions during endotoxin shock in rats.

Endogenous opioids are known to mediate some of the cardiovascular sequelae of sepsis. Inhibition of adrenergic action has been implicated as a physiological path by which endogenous opioids cause deleterious changes in cardiovascular function during endotoxin shock, but where and to what extent this accounts for changes in regional vascular resistance remains unclear. In this study, we addressed this question by examining the role of alpha-adrenergic actions in cardiovascular performance and the regional perfusion changes caused by naloxone during endotoxin shock. Rats had catheters inserted into the tail artery, left cardiac ventricle, and jugular vein. Twenty-four hours later, rats received saline or endotoxin (2 mg/kg) challenge intravenously over 30 min, followed at 40 min by intravenous naloxone (or saline) treatment (4 mg/kg + 2 mg/kg x h) in the presence or absence of phentolamine (100 micrograms/kg + 600 micrograms/kg x h) or yohimbine (40 micrograms/kg + 4 micrograms/kg x h). Radiolabeled microspheres were used to determine cardiac outputs and blood flows at 0, 30, 60, and 120 min after beginning endotoxin infusion. Naloxone attenuated the endotoxin-induced decline in mean arterial pressure (MAP) and cardiac output (CO), but had no effect on increased systemic vascular resistance (SVR). Phentolamine blocked naloxone's ability to increase MAP and CO, but permitted an increase in SVR by naloxone. In the presence of yohimbine, naloxone still increased MAP, but not CO nor SVR. Regional vascular responses varied, with naloxone demonstrating a vasoconstrictive effect despite alpha-adrenergic receptor blockade in some beds, and no effect in others. The response of individual organs in the hepatosplanchnic circulation was heterogenous as well. These data suggest that some effects of endogenous opioids during endotoxin shock are mediated via inhibition of alpha-adrenergic effects, but that some cardiovascular effects of endogenous opioids are independent of adrenergic control during endotoxin shock.

Cardiovascular effects of conventional sulfonylureas and glimepiride.

Sulfonylureas have, in the past, been reported to have adverse cardiovascular effects. Glimepiride is a new sulfonylurea. In spite of stimulating less insulin secretion, it has, depending on the species, equal or higher blood glucose decreasing activity and according to preliminary studies less cardiovascular activity than glibenclamide. Further studies were performed to confirm the lower cardiovascular activity of glimepiride. The IC50 for inhibition of rilmakalim-activated KATP channel currents in isolated ventricular myocytes was 31.6 nM for glimepiride and 6.8 nM for glibenclamide. In endotoxin shock-rats at a dose of 1 x 2 mg/kg i.v., glibenclamide induced a significantly higher blood pressure increase than glimepiride. At two i.v. doses of 20 mg/kg 4 min apart, in normal rats, glibenclamide produced signs of ischemia in the ECG in nearly all animals, glimepiride almost none, in diabetic rats, glibenclamide produced in all animals a lethal cardiogenic shock preceeded by serious ECG changes, glimepiride only in one fifth of the animals. In open-chest dogs, on intracoronary infusion of equieffective blood glucose-lowering doses, glibenclamide, gliclazide and glimepiride all reduced coronary blood flow, increased coronary resistance, depressed the mechanical activity of the heart, enhanced myocardial O2-extraction, reduced the serum potassium level and induced a moderate endocardial ST-segment elevation, but glimepiride to a significantly less extent than glibenclamide and gliclazide. The presented data confirm that glimepiride at equivalent blood glucose decreasing doses has less cardiovascular activity than conventional sulfonylureas.

Augmented sensitivity to benzodiazepine in septic shock rats.

The purpose of this study was to assess the pharmacological characteristics of the benzodiazepine binding site in the brain of septic animals. We induced endotoxin shock in rats using a caecum ligation and puncture model. Following examination of the physiological state of the rats 24 hr after the caecum ligation and puncture, brain tissue samples were prepared for biochemical assay of amino acids and for the [3H]-diazepam radioligand binding assay. Amino acids assays indicated that the concentration of aromatic amino acids was higher in the CLP group (P< 0.05), the branched chain amino acid concentration was lower in the CLP group (P< 0.05) and the sulfur-containing amino acid concentration was elevated in the CLP group (P< 0.05) than in both the control and the sham-operated groups. [3H]-diazepam radioligand binding assays demonstrated that the number of receptors in the septic rats was increased in the forebrain (CLP rats; 2.37 +/- 0.04 pmol x mg(-1) protein, control rats; 1.45 +/- 0.02 pmol x mg(-1) protein, sham-operated rats; 1.49 +/- 0.03 pmol x mg(-1) protein), cerebellum (CLP rats; 1.55 +/- 0.05 pmol x mg(-1) protein, control rats; 1.05 +/- 0.02 pmol x mg(-1) protein, sham-operated rats: 1.09 +/- 0.02 pmol x mg(-1) protein) and brain stem (CLP rats; 1.21 +/- 0.04 pmol x mg(-1) protein, control rats; 0.61 +/- 0.02 pmol x mg(-1) protein, sham-operated rats; 0.63 +/- 0.02 pmol x mg(-1) protein) compared with the control and sham-operated rats (P< 0.05). In conclusion, it was considered that the increased number of benzodiazepine receptors may be one cause of the neuronal alteration observed in septic shock animals.