cyclic-gmp and Shock--Septic

Sepsis and septic shock have high morbidity and mortality. The key point is that huge amount of nitric oxide (NO) is releasing into circulation, inducing marked dilation of blood vessels, and continuously decreased of blood pressure. The central link is inflammation and oxidative stress. Methylene blue can effectively inhibit NO, remove excessive NO and block the signal transduction pathway named inducible nitric oxide synthase-NO-soluble guanylate cyclase-cyclic guanosine monophosphate (iNOS-NO-sGC-cGMP). Meanwhile, it also play a role in inhibiting oxidative stress and inflammation. This paper reviews the mechanism of methylene blue in the treatment of sepsis and septic shock, as well as its treatment time window, optimal dose, administration mode and potential adverse reactions, to provide new ideas for clinical treatment.

Topics: Cyclic GMP; Guanylate Cyclase; Humans; Methylene Blue; Nitric Oxide; Sepsis; Shock, Septic

Among the numerous genes controlled by cyclic adenosine monophosphate (cAMP)/protein kinase A signalling machinery is the gene encoding the inducible nitric oxide synthase (iNOS), an enzyme catalyzing the synthesis of a highly reactive free radical nitric oxide (NO). While being a major microbicidal and tumoricidal molecule, iNOS-derived NO has also been implicated in tissue destruction, as well as in regulation of inflammatory/immune cell function in various disorders associated with excessive inflammation. A feasible way for cAMP-dependent therapeutic control of inflammation, including iNOS-mediated NO synthesis, could involve the administration of drugs that block the enzymatic activity of cAMP-degrading phosphodiesterases (PDE). Indeed, cAMP-elevating PDE inhibitors can influence iNOS activation in different cell types in vitro, and their potent anti-inflammatory effects in experimental disease models and clinical studies were frequently accompanied with profound modulation of NO production. A set of conflicting data has been generated over the years, ranging from strong suppression to marked enhancement of NO release by cAMP-increasing PDE inhibitors, depending on cell-type, iNOS stimuli, and/or the agents used. The present review summarizes the data on iNOS modulation by cAMP-elevating PDE inhibitors and possible mechanisms behind it, speculating on its contribution to the therapeutic effects of these drugs.

Topics: Animals; Autoimmune Diseases; Clinical Trials as Topic; Cyclic AMP; Cyclic GMP; Enzyme Activation; Humans; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Phosphodiesterase Inhibitors; Shock, Septic

Topics: Animals; Cardiomyopathies; Cyclic GMP; Cytokines; Humans; Myocardial Contraction; Myocardial Depressant Factor; Nitric Oxide; Shock, Septic

Shock can be defined as the failure of the circulatory system to provide necessary cellular nutrients, including oxygen, and to remove metabolic wastes. Although it is now recognized that more than 100 different forms of shock exist, this recognition is more a reflection of the widespread use of the term to describe a variety of disease states. For the purpose of this monograph, we concentrate on various forms of cardiovascular shock, in particular, shock that may be linked to inappropriate vasodilation from overproduction of the endogenous vasodilator, nitric oxide. Some forms of shock have been extensively studied, and convincing evidence exists for the role of nitric oxide. Other disease states have been less well characterized in terms of their association with excess nitric oxide production. Available evidence of a role for nitric oxide is discussed in the hope of stimulating the interest of investigators to explore these areas more thoroughly.

Topics: Anaphylaxis; Animals; Cyclic GMP; Cytokines; Depression, Chemical; Endothelium; Enzyme Inhibitors; Heart; Humans; Nitric Oxide; Nitric Oxide Synthase; Oxygen Consumption; Shock, Cardiogenic; Shock, Septic; Toxins, Biological; Vasodilation

Refractory hypotension is the main cause of death of patients with septic shock. It has been shown that an excessive release of NO is responsible for the sepsis-induced hypotension and vascular hyporeactivity. Nitric oxide is produced under normal conditions by a constitutive enzyme present, among other cell types, in the endothelial cell, and is necessary for maintenance of normal organ perfusion. Under inflammatory or septic conditions, a new enzyme is expressed in phagocytic cells and vascular smooth muscle cells, giving rise to an uncontrolled NO production that is associated with cytotoxic effects and vasodilatation. Randomized clinical trials have shown that the administration of inhibitors of NO synthesis to patients with septic shock is associated with a greater incidence of shock resolution, without significant adverse effects. The recent discovery of the different biological functions of NO, both under normal and inflammatory conditions, has allowed the development of new concepts about the pathophysiology of septic shock, and has provided the bases to design novel therapeutic strategies for the treatment of septic shock, based on the inhibition of NO synthesis.

Topics: Arginine; Cyclic GMP; Endothelium, Vascular; Enzyme Inhibitors; Humans; Hypotension; Leukocytes; Nitric Oxide; Nitric Oxide Synthase; Phagocytes; Randomized Controlled Trials as Topic; Shock, Septic

Septic shock is a life-threatening clinical situation associated with acute myocardial and vascular dysfunction, whose pathophysiology is still poorly understood. Herein, we investigated microRNA-155-dependent mechanisms of myocardial and vascular dysfunction in septic shock.. Prospective, randomized controlled experimental murine study and clinical cohort analysis.. University research laboratory and ICU at a tertiary-care center.. Septic patients, ICU controls, and healthy controls. Postmortem myocardial samples from septic and nonseptic patients. Ex vivo evaluation of arterial rings from patients undergoing coronary artery bypass grafting.. C57Bl/6J and genetic background-matched microRNA-155 knockout mice.. Two mouse models of septic shock were used. Genetic deletion and pharmacologic inhibition of microRNA-155 were performed. Ex vivo myographic studies were performed using mouse and human arterial rings.. We identified microRNA-155 as a highly up-regulated multifunctional mediator of sepsis-associated cardiovascular dysfunction. In humans, plasma and myocardial microRNA-155 levels correlate with sepsis-related mortality and cardiac injury, respectively, whereas in murine models, microRNA-155 deletion and pharmacologic inhibition attenuate sepsis-associated cardiovascular dysfunction and mortality. MicroRNA-155 up-regulation in septic myocardium was found to be mostly supported by microvascular endothelial cells. This promoted myocardial microvascular permeability and edema, bioenergetic deterioration, contractile dysfunction, proinflammatory, and nitric oxide-cGMP-protein kinase G signaling overactivation. In isolate cardiac microvascular endothelial cells, microRNA-155 up-regulation significantly contributes to LPS-induced proinflammatory cytokine up-regulation, leukocyte adhesion, and nitric oxide overproduction. Furthermore, we identified direct targeting of CD47 by microRNA-155 as a novel mechanism of myocardial and vascular contractile depression in sepsis, promoting microvascular endothelial cell and vascular insensitivity to thrombospondin-1-mediated inhibition of nitric oxide production and nitric oxide-mediated vasorelaxation, respectively. Additionally, microRNA-155 directly targets angiotensin type 1 receptor, decreasing vascular angiotensin II reactivity. Deletion of microRNA-155 restored angiotensin II and thrombospondin-1 vascular reactivity in LPS-exposed arterial rings.. Our study demonstrates multiple new microRNA-155-mediated mechanisms of sepsis-associated cardiovascular dysfunction, supporting the translational potential of microRNA-155 inhibition in human septic shock.

Topics: Angiotensin II; Animals; Blood Vessels; Cells, Cultured; Cyclic GMP; Endothelial Cells; Heart; Humans; Male; Mice; Mice, Inbred C57BL; MicroRNAs; Myocardium; Nitric Oxide; Prospective Studies; Random Allocation; Shock, Septic; Signal Transduction

Excessive production of nitric oxide (NO) by inducible NO synthase (iNOS) is thought to underlie the vascular dysfunction, systemic hypotension and organ failure that characterize endotoxic shock. Plasma levels of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) are raised in animal models and humans with endotoxic shock and correlate with the associated cardiovascular dysfunction. Since both NO and natriuretic peptides play important roles in cardiovascular homeostasis via activation of guanylate cyclase-linked receptors, we used mice lacking natriuretic peptide receptor (NPR)-A (NPR1) to establish if natriuretic peptides contribute to the cardiovascular dysfunction present in endotoxic shock.. Wild-type (WT) and NPR-A knockout (KO) mice were exposed to lipopolysaccharide (LPS) and vascular dysfunction (in vitro and in vivo), production of pro-inflammatory cytokines, and iNOS expression and activity were evaluated.. LPS-treated WT animals exhibited a marked fall in mean arterial blood pressure (MABP) whereas NPR-A KO mice maintained MABP throughout. LPS administration caused a greater suppression of vascular responses to the thromboxane-mimetic U46619, ANP, acetylcholine and the NO-donor spermine-NONOate in WT versus NPR-A KO mice. This differential effect on vascular function was paralleled by reduced pro-inflammatory cytokine production, iNOS expression and activity (plasma [NO(x)] and cyclic GMP).. These observations suggest that NPR-A activation by natriuretic peptides facilitates iNOS expression and contributes to the vascular dysfunction characteristic of endotoxic shock. Pharmacological interventions that target the natriuretic peptide system may represent a novel approach to treat this life-threatening condition.

Topics: Animals; Aorta, Thoracic; Blood Pressure; Cyclic GMP; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Hemodynamics; Inflammation Mediators; Lipopolysaccharides; Male; Mice; Mice, Knockout; Nitric Oxide; Nitric Oxide Synthase Type II; Receptors, Atrial Natriuretic Factor; Shock, Septic; Time Factors; Vasoconstriction; Vasoconstrictor Agents; Vasodilation; Vasodilator Agents

One of the clinical characteristics associated with septic shock is heart failure. Several lines of evidence indicate that functional consequences of heart failure in septic shock are linked to the activated NO-cyclic guanosine monophosphate (NO-cGMP) pathway. We have previously shown that the high-affinity cGMP export transporter, multidrug resistance protein 5 (MRP5), is expressed in the heart, which modulates intracellular concentrations and, hence, the effects of cGMP. Thus, modified expression of cardiac MRP5 in septic shock can alter cGMP concentrations and contribute to the development of heart failure. We therefore investigated MRP5 expression in the heart using two established murine models of septic shock (intraperitoneal LPS injection and surgical implantation of a stent into the ascending colon, resulting in a multibacterial peritonitis [CASP, colon ascendens stent peritonitis] in C57BL/6N mice, respectively; n = 38). Cardiac MRP5 was assessed by quantitative polymerase chain reaction and immunofluorescence. The protein was localized in the endothelial wall, smooth muscle, and cardiac myocytes. MRP5 mRNA expression was significantly reduced compared with controls both in the LPS (31.9 +/- 16.8 x 10(-4) vs. 54.1 +/- 14.8 x 10(-4), P = 0.025) and CASP model (18.3 +/- 9.4 x 10(-4) vs. 42.8 +/- 12.1 x 10(-4), P = 0.009; MRP5/glyceraldehyde 3-phosphate dehydrogenase copy numbers, respectively). In parallel, IL-6 plasma levels were significantly increased in both models. Incubation of cultured murine cardiomyocytes (HL1) with 5 ng/mL IL-6 resulted in decreased expression of MRP5 (54% of control), as did incubation of the cells with serum from septic mice (LPS serum, 22% of control; CASP serum, 11% of control). In conclusion, cardiac expression of the cGMP export transporter MRP5 is decreased in two murine models of septic shock, most likely by a transcriptional mechanism. Reduced cGMP export as a consequence of decreased MRP5 expression can attenuate heart failure in sepsis.

Topics: Animals; Cells, Cultured; Colon; Cyclic GMP; Disease Models, Animal; Endothelium; Female; Gene Expression Regulation; Glyceraldehyde-3-Phosphate Dehydrogenases; Heart Failure; Interleukin-6; Lipopolysaccharides; Mice; Multidrug Resistance-Associated Proteins; Myocardium; Myocytes, Cardiac; Myocytes, Smooth Muscle; Nitric Oxide; Peritonitis; Polymerase Chain Reaction; RNA, Messenger; Shock, Septic; Stents

Angiotensin II receptor subtypes (AT1 and AT2) have been shown to modulate microvascular fluid leak. However, their intracellular signal transduction pathways have not been elucidated. We hypothesized that AT1 activation exerts its permeability-increasing effect by provoking cGMP synthesis and inducing cAMP degradation and that AT2 activation decreases fluid leak by stimulating cAMP synthesis and enhancing cGMP degradation.. Using a microcannulation technique, hydraulic permeability (Lp) was measured in rat mesenteric venules. The messenger signal transduction of ATI was studied during continuous perfusion with the AT1 agonist, Sar1 plus either 1) a cGMP synthesis inhibitor, LY83583, or 2) an inhibitor of cAMP degradation, Rolipram. Likewise, AT2 signal transduction was studied with the AT2 agonist, CGP42112A, plus either 1) a cAMP synthesis inhibitor, dideoxyadenosine, or 2) an inhibitor of cGMP degradation, Zaprinast. Lp values are represented as mean +/- SEM x 10(-7) cm/s/cm H2O. For each group n = 6.. Inhibition of cGMP synthesis blunted the permeability-increasing effect of AT1 agonism and decreased the peak Lp from 4.91 +/- 0.25 to 2.30 +/- 0.10 (P < 0.001). Inhibition of cAMP degradation also reduced the effect of AT1 agonism on peak L(p) from 2.25 +/- 0.22 to 1.30 +/- 0.13 (P < 0.001). Meanwhile, cAMP synthesis inhibition completely blocked the permeability-decreasing effect of AT2 agonism during which Lp increased from a baseline of 0.92 +/- 0.08 to a peak of 4.38 +/- 0.20 (P < 0.001). During inhibition of cGMP degradation, AT2 activation was able to decrease peak Lp from 2.26 +/- 0.15 to 1.46 +/- 0.05 (P < 0.001).. When cGMP synthesis and cAMP degradation were inhibited, the effect on fluid leak by AT1 activation was blunted. Inhibition of cAMP synthesis completely blocked the effect of AT2 activation on fluid leak, while AT2 activation continued to decrease fluid leak despite inhibition of cGMP degradation. The AT1 receptor appears to increase fluid leak by stimulating both cGMP synthesis and cAMP degradation, while the AT2 receptor decreases fluid leak by stimulating cAMP synthesis, but not cGMP degradation.

Topics: Animals; Capillary Permeability; Cyclic AMP; Cyclic GMP; Female; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Shock, Hemorrhagic; Shock, Septic; Signal Transduction

The expression of inducible nitric-oxide synthase (iNOS) and subsequent "high-output" nitric oxide (NO) production underlies the systemic hypotension, inadequate tissue perfusion, and organ failure associated with septic shock. Therefore, modulators of iNOS expression and activity, both endogenous and exogenous, are important in determining the magnitude and time course of this condition. We have shown previously that NO from the constitutive endothelial NOS (eNOS) is necessary to obtain maximal iNOS expression and activity following exposure of murine macrophages to lipopolysaccharide (LPS). Thus, eNOS represents an important regulator of iNOS expression in vitro. Herein, we validate this hypothesis in vivo using a murine model of sepsis. A temporal reduction in iNOS expression and activity was observed in LPS-treated eNOS knock-out (KO) mice as compared with wild-type animals; this was reflected in a more stable hemodynamic profile in eNOS KO mice during endotoxaemia. Furthermore, in human umbilical vein endothelial cells, LPS leads to the activation of eNOS through phosphoinositide 3-kinase- and Akt/protein kinase B-dependent enzyme phosphorylation. These data indicate that the pathogenesis of sepsis is characterized by an initial eNOS activation, with the resultant NO acting as a co-stimulus for the expression of iNOS, and therefore highlight a novel pro-inflammatory role for eNOS.

Topics: Animals; Aorta; Blood Pressure; Blotting, Western; Bone Marrow Cells; Cells, Cultured; Chromones; Cyclic GMP; Endothelium, Vascular; Enzyme Inhibitors; Inflammation; Lipopolysaccharides; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Morpholines; Nitrates; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Nitrites; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Rotenone; Sepsis; Shock, Septic; Time Factors; Tissue Distribution

We examined pharmacologically the influence of nitric oxide (NO), guanosine 3':5'-cyclic monophosphate (cyclic GMP), adenine 3':5'-cyclic monophosphate (cyclic AMP), and protein kinase C-linked signaling pathways on relaxation to potassium in aortic segments isolated from rats treated for 6 h with bacterial endotoxin (lipopolysaccharide). Endotoxemia for 6 h was associated with a severe hypotension and vascular hyporeactivity to norepinephrine (NE), and an increase in plasma NO in vivo and aortic NO ex vivo. The NE-induced contraction was attenuated and the potassium-induced relaxation was accentuated in the aorta of rats with endotoxic shock. Ouabain inhibited the potassium-induced relaxation in aortae from normal and endotoxemic rats. 8-Bromo-cyclic GMP significantly enhanced the potassium-induced relaxation in control aortae, whereas 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) abolished this difference between normal and endotoxemic rats. In contrast, inhibition of potassium-induced relaxation was observed in aortae from normal and endotoxemic rats treated with 8-bromo-cyclic AMP or phorbol 12-myristate 13-acetate. Individually, inhibitors of protein kinase A or protein kinase C did not significantly alter relaxation to potassium; however, in combination, these inhibitors significantly potentiated relaxation in aortae from control rats. These results suggest that activity of Na(+)-K(+)-ATPase is enhanced in the vascular bed of animals with endotoxic shock and that this elevation in activity is mediated by NO-cyclic GMP, but not by cyclic AMP-protein kinase A or protein kinase C.

Topics: Animals; Aorta; Cyclic AMP-Dependent Protein Kinases; Cyclic GMP; Dose-Response Relationship, Drug; Endotoxemia; Endotoxins; Enzyme Activation; Enzyme Inhibitors; Male; Nitrates; Nitric Oxide; Ouabain; Oxadiazoles; Potassium; Protein Kinase C; Quinoxalines; Rats; Rats, Inbred WKY; Shock, Septic; Signal Transduction; Sodium-Potassium-Exchanging ATPase; Tetradecanoylphorbol Acetate; Time Factors

To evaluate the anti-sepsis potential of YC-1, we have examined the effect of YC-1 on the regulation of cytokine production in human leukocytes and endotoxemic mice. The data demonstrated that YC-1 showed a preferential inhibition on proinflammatory cytokine production without inhibition of cell growth or induction of cytotoxicity in human leukocytes. On the other hand, in the septic mouse model, treatment with an intraperitoneal application of LPS caused a cumulative death within 27 hours. The post-treatment administration of YC-1 significantly increased the survival rate in endotoxemic mice. Furthermore, several mediators were detected and the data showed that YC-1 profoundly blocked LPS-induced NO as well as TNF-alpha production, and prevented lung damage by histological examination. Samples from the animal model showed that LPS-induced NF-kappaB/DNA binding activity and consequent up-regulation of iNOS expression in tissues were abolished by post-administration of YC-1. Furthermore, YC-1, by itself, did not modify cGMP content while significantly inhibit LPS-induced cGMP formation, suggesting that YC-1-mediated effect was not through a cGMP-elevating pathway. Taken together, it is evident that the post-treatment administration of YC-1 after LPS application significantly inhibits NF-kappaB activation, iNOS expression, NO over-production, and cytokine release reaction resulting in an improved survival rate in endotoxemic mice. It is suggested that YC-1 may be a potential agent for the therapeutic treatment of sepsis.

Topics: Animals; Blotting, Western; Cyclic GMP; Cytokines; Disease Models, Animal; DNA; Endotoxemia; Humans; Immunohistochemistry; Indazoles; Leukocytes; Leukocytes, Mononuclear; Lipopolysaccharides; Lung; Male; Mice; Mice, Inbred ICR; NF-kappa B; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Platelet Aggregation Inhibitors; Rats; Rats, Wistar; Shock, Septic; Time Factors; Up-Regulation

Topics: Animals; Cells, Cultured; Cyclic GMP; Cytokines; Feedback; Humans; In Vitro Techniques; Inflammation Mediators; Myocardial Contraction; Myocardium; Myocytes, Cardiac; Nitric Oxide; Nitric Oxide Donors; Shock, Septic

To study the effect of cGMP-dependent protein kinase (PKG) on the pathogenesis of septic shock.. Confluent endothelial cells were disintegrated and centrifugated to obtain cell lysates after being treated with LPS or PKG activator 8-Br-cGMP. PKG activity of lysates was measured with radioactive isotope label method in a reaction system of phosphorylation of specific substrate H2B by PKG, and the shape and the distribution of intracellular filamentous actin were detected by specific fluorescence staining. For the control study, the PKG specific inhibitor KT5823 was used to pretreat the endothelial cells before the administration of LPS or PKG activator 8-Br-cGMP.. Exposure to LPS for 5, 10, 30 and 60 minutes led to a rapid time-dependent increase in endothelial PKG activity (P < 0.01 compared to the blank) and the polar distribution of intracellular filamentous actin and preincubation with KT5823 abolished these effects. 8-Br-cGMP was similar to LPS.. The results suggested that LPS can mediate PKG activation and the stress variety of filamentous actin in the vascular endothelial cells, which probably induce the endothelial hyperpermeability after septic shock.

Topics: Capillary Permeability; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Cytoskeleton; Endothelium, Vascular; Humans; Lipopolysaccharides; Shock, Septic; Signal Transduction

Identification and characterization of myocardial depressant factors present in meningococcal septicemia.. Laboratory investigation of myocardial depression that used isolated cardiac myocytes as an model of cardiac contractile function.. University hospital and laboratories.. Children with severe meningococcal septic shock requiring intensive care.. Myocytes obtained from adult male Sprague-Dawley rats.. Serum samples obtained from the acute phase of sepsis were evaluated for the presence of myocardial depressant activity. Further characterization of the myocardial depressant factor was undertaken by using cell culture supernatants from whole blood and peripheral blood mononuclear cells that had been exposed to heat-killed meningococci.. Myocardial depressant activity was measured by using isolated rat left-ventricular myocytes. Changes in amplitude of contraction and in the speed of contraction and relaxation were determined after cells were exposed to various stimuli. Serum from patients with meningococcal disease had myocardial depressant activity. This activity was also present in whole blood and peripheral blood mononuclear cells exposed to meningococci. Myocardial depressant activity was found to be heat stable, proteinaceous, and of a molecular weight range of 10-25 kDa. The activity did not elevate concentrations of cyclic guanylic acid. Lipopolysaccharide-binding protein augmented the release of myocardial depressant factor by peripheral blood mononuclear cells exposed to meningococci.. Myocardial depression in meningococcal sepsis is mediated in part by circulating myocardial depressant factors. Myocardial depressant factors are also released when whole blood or peripheral blood mononuclear cells of healthy donors are exposed to heat-killed meningococci. Release of the factors appears to be mediated through endotoxin-induced activation of peripheral blood mononuclear cells, since lipopolysaccharide-binding protein augments release in a dose-responsive manner. Partial physicochemical characterization of the factors has been achieved.

Topics: Adolescent; Animals; Cells, Cultured; Child; Child, Preschool; Cyclic GMP; Female; Humans; In Vitro Techniques; Infant; Interleukin-1; Leukocytes, Mononuclear; Male; Meningococcal Infections; Myocardial Contraction; Myocardial Depressant Factor; Myocytes, Cardiac; Neisseria meningitidis, Serogroup C; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Rats; Rats, Sprague-Dawley; Sepsis; Shock, Septic; Tumor Necrosis Factor-alpha

The molecular mechanisms responsible for sepsis-induced myocardial dysfunction remain undefined. CD14 mediates the inflammatory response to lipopolysaccharide (LPS) in various organs including the heart. In this study we investigated the role of CD14 in LPS-induced myocardial dysfunction in vivo.. Wild-type and CD14-deficient (CD14-D) mice were challenged with Escherichia coli LPS. Myocardial tumor necrosis factor, interleukin-1beta (IL-1beta), and NOS2 induction was measured before and 6 hours after LPS challenge. Echocardiographic parameters of left ventricular function were measured before and 6 hours after LPS administration. LPS challenge induced a significant increase in myocardial tumor necrosis factor and IL-1beta mRNA and protein expression in wild-type mice. In contrast, mRNA and protein levels for TNF and IL-1beta were significantly blunted in CD14-D mice. An increase in NOS2 protein was noted within 6 hours of LPS provocation only in the hearts of wild-type mice. This was associated with an increase in ventricular cGMP levels. Activation of nuclear factor-kappaB was observed within 30 minutes of LPS in the hearts of wild-type mice but not in CD14-D mice. In wild-type mice, LPS significantly decreased left ventricular fractional shortening, velocity of circumferential shortening, and dP/dt(max). LPS-treated CD14-D mice maintained normal cardiac function.. These results suggest that CD14 is important in mediating the proinflammatory response induced by LPS in the heart and that CD14 is necessary for the development of left ventricular dysfunction during LPS-induced shock in vivo.

Topics: Animals; Cyclic GMP; Female; Heart Ventricles; Hemodynamics; Inflammation; Interleukin-1; Lipopolysaccharide Receptors; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardium; NF-kappa B; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; RNA, Messenger; Shock, Septic; Tumor Necrosis Factor-alpha; Ultrasonography; Ventricular Dysfunction, Left

We have previously shown that an increase in NO activity activated ATP-sensitive potassium channel (K(ATP)) and shortened action potential duration (APD) in an endotoxic shock model. Because the increase in NO production and the decrease of APD appear to be downstream late events in endotoxic shock, we hypothesized that a common signaling pathway might mediate these effects.. Using a guinea pig model of endotoxic shock, we investigated the effect of genistein and tyrphostin AG 556 on the cardiac action potential. Adult Hartley guinea pigs (300 to 450 gm) were randomized into 2 treatment parts. In the chronic treatment part, guinea pigs were randomized to receive daily subcutaneous injection of one of the five agents: saline, genistein, tyrphostin AG 556, daidzein, and vehicle for 10 days. In the acute treatment part, these agents were administered by intraperitoneal injection 1 hour before endotoxic shock. The animals were then anesthetized and mechanically ventilated, and underwent 6-hour endotoxic shock or sham experiment.. In the chronic treatment part, the plasma nitrate concentration, myocardial guanosine 3',5'-cyclic monophosphate (cGMP) content, and APD at 90% repolarization (APD90) of papillary muscle showed no difference in the five groups before endotoxic shock. After 6-hour endotoxic shock, the elevation of plasma nitrate concentration and myocardial cGMP content was found significant in the control, the daidzein, and the vehicle groups, but was blunted in the genistein and the tyrphostin groups. The shortening of APD90 of papillary muscle was also significant in the control, the daidzein, and the vehicle groups, but blunted in the genistein and tyrphostin groups. There were similar findings in the acute treatment part, except the weaker effect of genistein and tyrphostin.. Genistein and tyrphostin AG 556, either administered chronically or acutely, significantly attenuate the cardiac APD shortening in endotoxic shock, presumably through the decrease in the plasma nitrate and the cardiac cGMP production. It is suggested that tyrosine kinase signaling plays an important role in the modulation of APD in endotoxic shock.

Topics: Action Potentials; Animals; Cyclic GMP; Female; Genistein; Guinea Pigs; Heart; Male; Myocardium; Nitrates; Nitric Oxide; Papillary Muscles; Potassium Channels; Shock, Septic; Tyrphostins

To assess the value of alpha-atrial natriuretic peptide (alpha-ANP), second messenger cyclic guanosine monophosphate (cGMP,) and endothelin as markers of myocardial depression in septic shock.. Prospective observational study.. Medical intensive care unit (ICU) of a university hospital.. Fourteen consecutive patients with septic shock and arterial and pulmonary artery catheters in place.. Hemodynamic variables and plasma levels of alpha-ANP, cGMP, and endothelin were measured every 6 hrs for 3 days after admission. Eight patients died from shock in the ICU. The nadir left ventricular stroke work index (LVSWI) was below 35 g/m2 in all patients, and the median peak circulating alpha-ANP (n < 68 pg/mL) was 276 pg/mL (range, 79-1056), the median peak cGMP (n < 2.1 ng/mL) was 8.1 ng/mL (range, 3.2-29.7), and the median peak endothelin (n < 5.3 pg/mL) was 15.5 pg/mL (range, 8.5-33.9), supranormal in all patients. Outcome groups differed in the course of cardiac index and LVSWI, which were lower in nonsurvivors despite similar filling pressures and more intensive inotropic treatment (p < .01). The course of alpha-ANP, cGMP, and endothelin plasma levels also differed between groups, with higher levels in nonsurvivors (p < .05). As for pooled data, the mean daily or nadir LVSWI inversely related to mean daily or peak alpha-ANP, cGMP, and endothelin levels, respectively (p < .05). The area under the receiver operating characteristic curve for myocardial depression (LVSWI < 35 g/m2) was for alpha-ANP and endothelin 0.77, and for cGMP 0.85 (p < .01). The optimum cutoff values for alpha-ANP, cGMP, and endothelin were 172 pg/mL, 4.5 ng/mL, and 10.0 pg/mL, respectively. The sensitivity for myocardial depression of alpha-ANP, cGMP, and endothelin was 68%, 77%, and 72%, and the specificity was 82%, 93%, and 69%, respectively.. Circulating alpha-ANP, endothelin, and, particularly, cGMP may be markers of the myocardial depression of human septic shock, which is associated with mortality.

Topics: Adult; Aged; Aged, 80 and over; Atrial Natriuretic Factor; Biomarkers; Cardiomyopathies; Cyclic GMP; Endothelins; Female; Hemodynamics; Humans; Male; Middle Aged; Netherlands; Prognosis; Prospective Studies; Respiratory Mechanics; Sensitivity and Specificity; Shock, Septic; Statistics, Nonparametric; Survival Rate; Ventricular Function

We measured the concentrations of serum nitrates/nitrites and plasma cyclic guanosine monophosphate as markers of nitric oxide synthesis in patients with or without septic shock for 5 days following admission to intensive care. We found that nitrate/nitrite concentrations, when corrected for the effect of renal failure, were significantly higher in patients with septic shock, both on admission and in the final samples drawn. In a logistic regression analysis, the rate of change of nitrate/nitrite concentration was associated with survival to day 28 (falling in survivors). The concentration of cyclic guanosine monophosphate when corrected for the confounding effects of renal function and platelet count, was only associated with the septic shock group on admission.

Topics: Aged; APACHE; Biomarkers; Critical Care; Cyclic GMP; Female; Humans; Logistic Models; Male; Middle Aged; Nitrates; Nitric Oxide; Nitrites; Prognosis; Shock, Septic; Survival Rate

Nitric oxide (NO) plays a central role in the pathogenesis of septic shock. However, the role of the NO produced by endothelial NO synthase (eNOS) in septic shock is still unclear. We examined the effect of chronic eNOS overexpression and the role of eNOS-derived NO in lipopolysaccharide (LPS)-induced septic shock using eNOS transgenic (Tg) mice.. LPS was intraperitoneally injected into Tg and control mice. No differences existed in the peak plasma nitrate and nitrate levels induced by LPS between the 2 genotypes. In LPS-treated control mice, blood pressure progressively declined and reached 60% of basal levels (from 97+/-3 to 59+/-3 mm Hg) 24 hours after LPS injection. In contrast, the blood pressure of LPS-treated Tg mice fell only 15% from basal levels (from 84+/-4 to 71+/-4 mm Hg) after the first 6 hours and, thereafter, it remained at this level. LPS-induced increases in the expression of the mRNA of both vascular cell adhesion molecule-1 and intracellular adhesion molecule-1 in the lungs were significantly lower in Tg mice than in control mice. LPS-induced pulmonary leukocyte infiltration and increases in lung water content were also significantly attenuated in Tg mice. Histological examination revealed that lung injury after LPS injection was milder in Tg mice. Furthermore, Tg mice exhibited enhanced survival from LPS-induced septic shock compared with control mice.. Chronic eNOS overexpression in the endothelium of mice resulted in resistance to LPS-induced hypotension, lung injury, and death. These effects are associated with the reduced vascular reactivity to NO and the reduced anti-inflammatory effects of NO.

Topics: Animals; Aorta; Blood Pressure; Cyclic GMP; Edema; Female; Granulocytes; Hypotension; Immunity, Innate; Lipopolysaccharides; Lung; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Multiple Organ Failure; Nitrates; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Nitrites; Organ Size; Peroxidase; Shock, Septic; Vasodilation

To investigate the roles of nitric oxide and adenosine triphosphate (ATP)-sensitive potassium channels (KATP) in the shortening of cardiac action potential in endotoxic shock.. Prospective animal study with concurrent controls.. University animal research laboratory.. Adult Hartley guinea pigs, weighing 300-400 g.. Guinea pigs were anesthetized and mechanically ventilated for 6 hrs. Lipopolysaccharide (LPS) or saline (sham group) were given intravenously. Drug effects were examined at the end of 6 hrs.. Plasma nitrate concentration was measured hourly, while guanosine 3',5'-cyclic monophosphate (cGMP) content and action potential duration at 90% of repolarization (APD90) of papillary muscle were examined every 2 hrs in the 6-hr endotoxemia in both the sham and the LPS-treated groups. The basal levels of these three variables showed no difference in the two groups. In the sham group, these variables did not change significantly (n = 14 for plasma nitrate determination; n = 5 for cGMP content measurement; n = 5-14 for APD90 measurement; all p > .05). But in the LPS-treated group, both plasma nitrate concentration and cGMP content of papillary muscle showed time-dependent increases and they were significantly higher than those in the sham group (at the 6th hr, plasma nitrate: 42.6 +/- 7.7 vs. 21.8 +/- 3.1 micromol/L, both n = 14, p < .01; cGMP: 1.52 +/- 0.15 vs. 0.73 +/- 0.08 pmol/mg protein, both n = 5, p < .01). In contrast, APD90 revealed a time-dependent decrease compared with that in the sham group (at the 6th hr, 137.1 +/- 52 vs. 188.2 +/- 4.8 msecs, both n = 14, p < .001). In the following 60-min in vitro recording of action potentials after the end of 6-hr endotoxemia, the shortened APD90 in the LPS-treated group did not recover and remained shorter compared with that in the sham group, in which the APD90 showed no significant changes (at the 60th min, 165.1 +/- 5.7 vs. 200.2 +/- 3.8 msecs, each n = 14, p < .01). However, in the presence of glibenclamide, a specific KATP blocker (100 micromol/L; n = 10), the APD90 could be reversed almost completely to the same value as that in the sham group (n = 14) (196.6 +/- 3.5 vs. 200.2 +/- 3.8 msecs; p > .05), despite glibenclamide having no effect on the APD90 in the sham group. In the LPS-treated group, NG-nitro-L-arginine methyl ester (1 mmol/L; n = 4), methylene blue (10 micromol/L; n = 5), and aminoguanidine (100 micromol/L; n = 4) significantly prolonged the shortened APD90 (192.5 +/- 3.1, 195.0 +/- 3.3, and 176.5 +/- 3.3 msecs, respectively; p < .01, p < .01, and p < .05, respectively, compared with that without these agents, 165.1 +/- 5.7 msecs, n = 14). These agents had negligible effects on the APD90 in the sham group (all p > .05). Furthermore, 8-bromoguanosine-3',5'-cyclic monophosphate (500 micromol/L; n = 5) decreased APD in intact papillary muscle (mean reduction of APD90, 13.5 +/- 3.5%, n = 5; p < .05), an effect abolished by pretreatment with glibenclamide (100 micromol/L; n = 5) that did not. In this experimental model, we provide reasonably convincing evidence to suggest that in endotoxic shock, an increase in nitric oxide activity may activate KATP, which plays a major role in the shortening of APD, presumably through a cGMP-dependent pathway.

Topics: Action Potentials; Adenosine Triphosphate; Animals; Cyclic GMP; Enzyme Inhibitors; Glyburide; Guanidines; Guinea Pigs; Lipopolysaccharides; Methylene Blue; NG-Nitroarginine Methyl Ester; Nitric Oxide; Papillary Muscles; Potassium Channels; Shock, Septic; Time Factors

In this study, Gram-positive Staphylococcus aureus lipoteichoic acid (LTA) dose dependently (0.1-1.0 microg/mL) and time dependently (10-60 min) inhibited platelet aggregation in human platelets stimulated by agonists (i.e., thrombin and collagen). LTA also dose dependently inhibited intracellular Ca(2+) mobilization in human platelets stimulated by collagen. In addition, LTA (0.5 and 1.0 microg/mL) dose dependently increased the formation of cyclic AMP but not cyclic GMP in platelets. LTA (0.5 and 1.0 microg/mL) did not significantly increase the production of nitrate within a 10-min incubation period. Rapid phosphorylation of a platelet protein of M(r) 47,000, a marker of protein kinase C activation, was triggered by PDBu (0.03 microM). This phosphorylation was dose dependently inhibited by LTA (0.5 and 1.0 microg/mL) within a 10-min incubation period. Furthermore, LTA (0.5 and 1.0 microg/mL) also inhibited platelet aggregation induced by PDBu (0.03 microM) in human platelets. These results indicate that the antiplatelet activity of LTA may be involved in the increase of cyclic AMP, leading to inhibition of intracellular Ca(2+) mobilization and protein kinase C activity. Therefore, LTA-mediated alteration of platelet function may contribute to bleeding diathesis in septicemic and endotoxemic patients.

Topics: Alprostadil; Blood Platelets; Blood Proteins; Calcium Signaling; Collagen; Cyclic AMP; Cyclic GMP; Cytokines; Enzyme Induction; Gram-Positive Bacteria; Humans; Lipopolysaccharides; Molecular Weight; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitroglycerin; Phorbol 12,13-Dibutyrate; Phosphorylation; Platelet Aggregation Inhibitors; Protein Kinase C; Protein Processing, Post-Translational; Second Messenger Systems; Shock, Septic; Staphylococcus aureus; Teichoic Acids

Acute endotoxemic renal failure involves renal vasoconstriction, which presumably occurs despite increased nitric oxide (NO) generation by inducible NO synthase in the kidney. The present study examined the hypothesis that the renal vasoconstriction during endotoxemia occurs in part because of desensitization of soluble guanylate cyclase (sGC). Endotoxic shock was induced in male B6/129F2/J mice by an intraperitoneal injection of Escherichia coli lipopolysaccharide. The endotoxemia resulted in shock and renal failure as evidenced by a decrease in mean arterial pressure and an increase in serum creatinine and urea nitrogen. Serum NO increased in a time-dependent manner, reaching the highest levels at 24 h, in parallel with induction of inducible NO synthase protein in the renal cortex. In renal cortical slices obtained from endotoxemic mice, cyclic guanosine monophosphate (cGMP) increased significantly at 6 h and 15 h as compared with control but normalized at 24 h after injection of lipopolysaccharide. Incubation of renal cortical slices in the presence of a phosphodiesterase inhibitor isobutylmethylxantine did not alter the pattern of changes in cGMP. Incubation of renal cortical slices with 2 mM sodium nitroprusside resulted in a similar accumulation of cGMP in slices taken from control and endotoxemic mice at 6 h and 15 h. However, in slices from 24-h endotoxemic mice, accumulation of cGMP in response to sodium nitroprusside was significantly lower. This lower stimulability of sGC was not paralleled by a decrease in its abundance in renal cortex on immunoblot. Taken together, these results demonstrate a desensitization of sGC in renal cortex during endotoxemia, which may contribute to the associated renal vasoconstriction.

Topics: Acute Kidney Injury; Animals; Cyclic GMP; Endotoxemia; Enzyme Induction; Guanylate Cyclase; Kidney Cortex; Male; Mice; Mice, Inbred Strains; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitroprusside; Shock, Septic; Solubility

Previous studies have demonstrated the existence of a circulating myocardial depressant substance during human septic shock. We have recently identified this substance as a synergistic combination of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). This study utilized an in vitro cardiac myocyte assay to evaluate the potential mechanistic role of nitric oxide (NO) and cGMP in depression of myocyte contractility induced by TNF-alpha, IL-1beta, TNF-alpha + IL-1beta (at low concentrations), and human septic shock serum (HSS). TNF-alpha, IL-1beta, TNF-alpha + IL-1beta, and each of 5 sera from patients with acute septic shock caused depression of both maximum extent and peak velocity of cardiac myocyte shortening and an increase in intracellular cGMP concentration during 30 min of exposure (minimum P < 0.01). NO synthetase (NOS) and guanylate cyclase inhibitors such as N-methyl-L-arginine (L-NMA) and methylene blue prevented these effects; an excess of L-arginine with L-NMA restored them (minimum P < 0.01). In contrast, D-arginine failed to reestablish cytokine-induced myocyte depression and cGMP accumulation prevented by L-NMA. Exposure of myocytes to TNF-alpha, IL-1beta, or TNF-alpha + IL-1beta produced a concentration-dependent increase in intracellular cGMP that paralleled the depression of cardiac myocyte contractility (minimum P < 0.001). In addition, TNF-alpha, IL-1beta, TNF-alpha + IL-1beta, or HSS application to cardiac myocytes resulted in increased NO gas generation, which was inhibited by L-NMA (minimum P < 0.01). Furthermore, unstimulated cardiac myocytes were shown to harbor constitutive but not inducible NOS activity. These data suggest that the sequential generation of NO by a constitutive NOS and cGMP by guanylate cyclase represents an important mechanism of cardiac myocyte depression by TNF-alpha, IL-1beta, TNF-alpha + IL-1beta, and the myocardial depressant substance(s) of septic shock.

Topics: Animals; Arginine; Blood Physiological Phenomena; Cyclic GMP; Drug Combinations; Enzyme Inhibitors; Humans; Interleukin-1; Methylene Blue; Myocardial Contraction; Myocardium; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Nucleotides, Cyclic; omega-N-Methylarginine; Rats; Shock, Septic; Tumor Necrosis Factor-alpha

Topics: Aging; Animals; Cyclic GMP; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; Heart; Hypoxia; In Vitro Techniques; Myocardial Ischemia; Myocardial Reperfusion; Myocardium; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitrites; Rabbits; Shock, Septic; Stress, Physiological; Transcription, Genetic; Ventricular Function, Left; Ventricular Function, Right

Topics: Animals; Aorta, Thoracic; Cell Wall; Cyclic GMP; Enzyme Induction; In Vitro Techniques; Lipopolysaccharides; Nitric Oxide; Nitric Oxide Synthase; Polysaccharides, Bacterial; Rats; Shock, Septic; Streptococcus mutans; Vasoconstriction

Acute endotoxic shock is accompanied by an increase in the production of nitric oxide (NO) by several different hepatic cell types. Platelet-activating factor (PAF) is a potent proinflammatory mediator with many pathophysiological actions and, in fact, elevated plasma and tissue levels of PAF are observed in animal models of endotoxic shock. The current study demonstrates that PAF induced nitrite formation, the end product of nitric oxide synthesis, by Kupffer cells in a dose- and time-dependent manner. Moreover, PAF was seen to initiate NO synthase gene expression and protein synthesis. PAF augmented lipopolysaccharide (LPS)-induced expression of inducible nitric oxide synthase messenger RNA (mRNA), protein, nitrite and cyclic guanosine monophosphate (cGMP) levels in Kupffer cells. Treatment of Kupffer cells with actinomycin D or cycloheximide inhibited PAF- and LPS-stimulated nitrite and nitric oxide synthase protein formation confirming that de novo synthesis of the enzyme occurred. In Kupffer cells, the presence of an arginine analog, NG-methyl-L-arginine, attenuated nitrite formation induced by PAF and LPS alone or in combination. L-arginine is the principal substrate for nitric oxide synthase. PAF and LPS individually and in combination induced a time-dependent uptake of L-[3H]-arginine into the Kupffer cell, and this response was sensitive to cycloheximide. The current study indicates that exogenous PAF contributes to the induction of nitric oxide synthase by LPS in cultured rat Kupffer cells.

Topics: Animals; Arginine; Biological Transport, Active; Cells, Cultured; Cyclic GMP; Cycloheximide; Dactinomycin; Drug Synergism; Enzyme Induction; Enzyme Inhibitors; Kinetics; Kupffer Cells; Lipopolysaccharides; Nitric Oxide; Nitric Oxide Synthase; omega-N-Methylarginine; Platelet Activating Factor; Protein Synthesis Inhibitors; Rats; RNA, Messenger; Shock, Septic

Lipopolysaccharide (LPS) induces early (within 1 h) and delayed (after several hours) impairment of vascular reactivity to catecholamines whose mechanisms are different, although they probably both involve nitric oxide (NO). Temporal and quantitative relationships between hyporeactivity to noradrenaline and NO production were investigated in a rat model of endotoxaemia allowing to clearly distinguish the two phases of hyporeactivity.. Anaesthetised rats were infused with LPS (14 mg kg-1 h-1) for 1 h. Pressure responses to noradrenaline (NA) and circulating NO derivatives (nitrosyl haemoglobin, NO2-, NO3-) were monitored for 5 h after the onset of infusion. Reactivity to NA and tissue cyclic GMP level were also assessed ex vivo, in aortic rings taken at different experimental times.. LPS-induced early hyporeactivity to NA was associated with a moderate but significant increase in plasma NO3- level, without any significant change in concentration of the other circulating NO derivatives. Neither reactivity ex vivo nor cyclic GMP content were modified in aortae taken after 1 h of LPS infusion. By contrast, delayed hyporeactivity (5 h after the onset of LPS infusion) was associated with a large increase in all circulating NO derivatives (up to 2.5 fold), enhanced aortic cyclic GMP level and aortic hyporeactivity ex vivo. Pre-treatment of rats with NG-nitro-L-arginine methyl ester (1 mg kg-1 i.v.) entirely prevented early hyporeactivity and rise in NO3- concentration. In addition it attenuated in comparable proportion both delayed hyporeactivity to NA in vivo and circulating levels of NO derivatives.. The results confirm the involvement of NO in the two phases of hyporeactivity to NA induced by LPS. They strongly support the view that a circulating factor is involved in triggering endothelial NO release during the early phase, whereas the delayed phase is associated with a high production of NO in vascular smooth muscle resulting from the induction of NO synthase.

Topics: Animals; Arginine; Blood Pressure; Cyclic GMP; In Vitro Techniques; Lipopolysaccharides; Male; Muscle Contraction; Muscle, Smooth, Vascular; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitrites; Norepinephrine; Rats; Rats, Wistar; Shock, Septic; Time Factors

The sensitivity of animals to endotoxin differs significantly between species. Thus, factors that determine the susceptibility to endotoxin may play important roles in the pathogenesis of septic shock. In order to determine the mechanism responsible for susceptibility to endotoxin, the effect of lipopolysaccharide (LPS) on the circulatory status of Propionibacterium acnes (PA)-sensitized rats was studied. Following the intravenous administration of a low dose of LPS, the arterial blood pressure of PA-treated rats, but not of normal animals, progressively decreased; the PA-sensitized animals died of circulatory shock within 7 h of LPS administration. N omega-nitro-L-arginine (NA) reduced the depressor effect of LPS by an L-arginine-inhibitable mechanism. Administration of LPS markedly increased the level of the inducible type of nitric oxide (NO) synthase in various tissues, including the aorta, of PA-treated rats but not of control animals. LPS also increased plasma levels of nitrate plus nitrite and aortic levels of cGMP. Dexamethasone inhibited the de novo synthesis of NO synthase in the aorta and other tissues and reduced the depressor effect of LPS. These and other findings suggest that induction of nitric oxide synthase in resistant arteries might underlie the pathogenesis of LPS-induced hypotension in PA-sensitized animals and the mechanism responsible for the susceptibility to endotoxin.

Topics: Amino Acid Oxidoreductases; Animals; Aorta; Arginine; Blood Pressure; Cyclic GMP; Dexamethasone; Enzyme Induction; Heart Rate; Hepatectomy; Hypersensitivity; Lipopolysaccharides; Male; Nitrates; Nitric Oxide Synthase; Nitrites; Nitroarginine; Propionibacterium acnes; Rats; Rats, Wistar; Shock, Septic; Splenectomy; Survival Analysis; Tissue Distribution

Among other effects, prostaglandins (PG) of the E series are known to inhibit several acute and chronic inflammatory conditions in vivo and proinflammatory cytokine production by activated macrophages in culture. The research presented here demonstrates that the inhibitory effect of PGE2 on tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) production by lipopolysaccharide (LPS)-stimulated murine peritoneal macrophages involves IL-10. In a dose-dependent manner, PGE2 inhibits LPS-induced release of TNF-alpha and IL-6, but not of lactate or nitric oxide. The decrease in the level of these cytokines is inversely proportional to the increase in immunoreactive IL-10. This differential inhibitory effect of PGE2 is mimicked by agents that elevate intracellular levels of cAMP, but not cGMP. Neutralizing anti IL-10 antibody but not neutralizing antibodies against other macrophage secretory products (IL-6, leukemia inhibitory factor, and transforming growth factor beta [TGF-beta]), significantly reverse the potent inhibitory effect of PGE2. In vivo, the administration of PGE2 before LPS challenge significantly reduces circulating TNF-alpha and IL-6 levels. Anti-IL-10 antibody substantially enhanced the LPS-induced TNF-alpha and IL-6 levels in mice that received either LPS alone or LPS plus PGE2. These results suggest that the anti-inflammatory effect of PGE2 on mononuclear phagocytes is mediated in part by an autocrine feedback mechanism involving IL-10.

Topics: 1-Methyl-3-isobutylxanthine; Analysis of Variance; Animals; Antibodies, Monoclonal; Biological Assay; Bucladesine; Cells, Cultured; Crosses, Genetic; Cyclic AMP; Cyclic GMP; Enzyme-Linked Immunosorbent Assay; Interleukin-10; Interleukin-6; Kinetics; Lactates; Lipopolysaccharides; Macrophage Activation; Macrophages, Peritoneal; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Nitric Oxide; Prostaglandins E; Shock, Septic; Tumor Necrosis Factor-alpha

Nitric oxide and atrial natriuretic peptides are the main activators of guanylyl cyclases, which transform GTP into cyclic GMP and thereby contribute to the decrease of vascular tone. To investigate the increase, if any, of plasma cyclic GMP concentrations in human patients with hyperdynamic circulation resulting from acute liver failure and to ascertain whether guanylyl cyclase activation is involved in the decline of systemic vascular resistance that occurs in this pathophysiological condition, we simultaneously recorded hemodynamic data and cyclic GMP levels in patients with fulminant liver failure before and after liver transplantation and in normokinetic patients undergoing abdominal nonseptic surgery. We also compared these data with those recorded in patients with hyperkinetic shock resulting from gram-negative sepsis or nitric oxide-independent vasomotor agent (carbamate) over-dose. In all these patients we simultaneously studied kidney function, platelet counts and atrial natriuretic peptides. Patients with fulminant liver failure had higher cyclic GMP concentrations than did control patients undergoing abdominal surgery (11.02 +/- 1.55 pmol.ml-1 vs. 1.77 +/- 0.18 pmol.ml-1, p < 0.001). At similar heart-loading conditions these concentrations were lower than those in gram-negative septic shock (18.2 +/- 1.35 pmol.ml-1, p < 0.05) but higher than those in carbamate-induced shock (3.6 +/- 0.7 pmol.ml-1, p < 0.01). In addition, cyclic GMP concentrations significantly decreased from the fulminant liver failure period to the posttransplantation period, although atrial natriuretic peptide levels did not change significantly and kidney function worsened.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adolescent; Adult; Atrial Natriuretic Factor; Blood Circulation; Carbamates; Cyclic GMP; Female; Guanylate Cyclase; Hemodynamics; Hepatic Encephalopathy; Humans; Kidney; Liver Failure, Acute; Liver Transplantation; Male; Middle Aged; Platelet Count; Prospective Studies; Shock; Shock, Septic; Vascular Resistance

Endotoxin and other bacterial products induce the release of mediators which alter the circulation and cellular metabolism. Recent evidence suggests nitric oxide (NO) is one such mediator. The proposed mechanism by which NO produces hypotension is the activation of guanylate cyclase with subsequent biosynthesis of 3':5' cyclic guanosine monophosphate (cGMP). We studied the production of cGMP during Escherichia coli-induced septic shock in two experiments; the first with sepsis alone and the second using NG-monomethyl-L-arginine (L-NMMA), a competitive inhibitor of nitric oxide synthase. Animals in both experiments experienced significant bacteremia (P < 0.05), endotoxemia (P < 0.05), and lactic acidosis (P < 0.03). Mean arterial blood pressure decreased (P < 0.03) and heart rate increased (P < 0.05) within both groups but did not differ between groups. A significant increase in the production of circulating whole blood cGMP occurred at 3-5 h (P < 0.03). There was significantly less cGMP produced by the L-NMMA-treated animals (P < 0.01). These results demonstrate an elevation in cGMP during septic shock which is attenuated by the addition of L-NMMA. This suggests that NO may be present during gram-negative septic shock and its effects mediated through cGMP.

Topics: Animals; Arginine; Bacteremia; Carbon Dioxide; Cyclic GMP; Escherichia coli Infections; Lactates; Lactic Acid; Male; Nitric Oxide; omega-N-Methylarginine; Rabbits; Shock, Septic

Hypotension in septic shock is a reflection of unregulated nitric oxide (NO) production and vascular smooth muscle guanylyl cyclase activation. We examined the effect of methylene blue on lipopolysaccharide (LPS)-induced shock in anesthetized rabbits. Shock was induced with 150 micrograms/kg LPS after measurement of mean arterial pressure, platelet cGMP, and total plasma NO (nitrogen monoxide+S-nitrosothiol) content. Measurements were repeated before and after the intravenous administration of 1, 5, and 10 mg/kg methylene blue in response to a 55% reduction in mean arterial pressure. At baseline, mean +/- SEM arterial pressure was 88 +/- 3 mm Hg, which fell to 51 +/- 3 mm Hg after LPS (P < .05). Methylene blue at doses of 1, 5, and 10 mg/kg produced a prompt dose-dependent increase in mean arterial pressure to 69 +/- 2, 77 +/- 3, and 81 +/- 2 mm Hg, respectively (P < .05 versus mean arterial pressure after LPS) in association with normalization of plasma total NO content (P < .05); however, methylene blue did not significantly affect intraplatelet cGMP levels. Thus, methylene blue restores normal arterial pressure in rabbits with septic shock. This effect is associated with persistent elevation of intraplatelet cGMP levels and normalization of total plasma NO content. These data are consistent with methylene blue-mediated inhibition of NO synthase and/or degradation of NO in this model and suggest a novel therapeutic approach to the treatment of septic shock.

Topics: Animals; Blood Pressure; Cyclic GMP; Hypotension; Lipopolysaccharides; Methylene Blue; Nitric Oxide; Rabbits; Shock, Septic; Sulfhydryl Compounds

To investigate the increase in plasma cyclic GMP (cGMP) concentrations in humans with hyperkinetic septic shock (SS) and to evaluate its relationship to low systemic vascular resistance (SVR).. Prospective clinical investigation.. Medical intensive care unit of a university hospital.. 22 patients with documented SS requiring hemodynamic resuscitation, respiratory support and--in some cases--hemodialysis.. Hemodynamic data were recorded at admission time and then twice a-day during the following 72 h. We simultaneously measured cyclic GMP, atrial natriuretic peptides (ANP), creatininemia and platelet counts. At admission time, higher plasma cGMP concentrations were observed in patients with SS (11.84 +/- 1.52 pmol.ml-1) than in healthy controls (1.77 +/- 0.18 pmol.ml-1, p < 0.0001), in septicemia patients without circulatory failure (3.28 +/- 0.36 pmol.ml-1, p < 0.005) or in patients with hyperkinetic non-septic shock (3.6 +/- 0.7 pmol.ml-1, p < 0.02). In contrast, there was no significant difference between patients with SS and controls with anuria from non-septic origin. Also ANP concentrations were higher in patients with SS than in others. In addition, cGMP levels correlated negatively with SVR during the first 48 h of the study, and positively with creatininemia later when renal function worsened. However, they did not correlate significantly with ANP.. These data demonstrate that a significant increase in plasma cGMP concentrations occurs during human SS and that it correlates with the decline in peripheral vascular resistance in the absence, but not in the presence, of severe renal failure. Furthermore, the increase in cGMP levels cannot be ascribed solely to enhanced ANP-induced particulate guanylyl cyclase activity. Thus, our results suggest the occurrence of another endogenous source of cGMP during hyperkinetic SS.

Topics: Acute Kidney Injury; Adult; Aged; Aged, 80 and over; Atrial Natriuretic Factor; Creatinine; Cyclic GMP; Female; Humans; Male; Middle Aged; Platelet Count; Prospective Studies; Shock, Septic; Vascular Resistance

The relationship between vascular tone and the induction by endotoxin of a nitric oxide (NO) synthase was studied in vitro in rings of rat thoracic aorta. In rings with and without endothelium there was a time-dependent induction of NO synthase accompanied by both spontaneous and L-arginine-induced relaxation and by reduced contractility to phenylephrine. These effects, which were attributable to the presence of endotoxin in the Krebs' buffer, were attenuated by cycloheximide, polymyxin B and inhibitors of NO synthase. Furthermore, dexamethasone inhibited the induction of NO synthase and the consequent effects on vascular tone. These findings indicate that prevention of the induction of NO synthase by glucocorticoids may be an important component of their therapeutic action.

Topics: Amino Acid Oxidoreductases; Animals; Aorta; Calcium; Cyclic GMP; Cycloheximide; Dexamethasone; Endothelium, Vascular; Endotoxins; Glucocorticoids; Hypertension; Kinetics; Lipopolysaccharides; Muscle Tonus; Myocardial Contraction; Nitric Oxide Synthase; Polymyxin B; Rats; Shock, Septic

The authors have studied the effect of Y. pestis "mouse" toxin (LD50), injected intravenously to rats, on cAMP and cGMP content in the tissues of different organs (the lungs, liver, heart, spleen, kidneys, small intestine) and in the blood in the course of the development of toxinfection shock. The effect of Y. pestis "mouse" toxin on cyclic nucleotide content in the organs of experimental animals is determined by the sum of oppositely directed effects produced by the thermostable and thermolabile fractions of the toxin. Its thermostable fraction, when introduced in the dose used in the experiments, did not kill the animals. The most pronounced changes in the cyclic nucleotide content have been detected in the lungs which appear to be the main target organ for Y. pestis "mouse" toxin.

Topics: Animals; Cyclic AMP; Cyclic GMP; Drug Stability; Injections, Intravenous; Rats; Shock, Septic; Time Factors; Tissue Distribution; Toxins, Biological; Yersinia pestis

Topics: Animals; Cyclic AMP; Cyclic GMP; Dogs; Escherichia coli; Parasympatholytics; Shock, Septic; Solanaceous Alkaloids

Topics: Acetylcholinesterase; Animals; Cyclic AMP; Cyclic GMP; Dogs; Endotoxins; Escherichia coli; Hemodynamics; Norepinephrine; Shock, Septic