Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0243026 (sepsis)
 52,417 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined vascular reactivity to vasoconstrictors [phenylephrine (PE), serotonin (5-HT), and high K+] and vasodilators [acetylcholine (ACh), A23187, L-arginine, and nitroglycerin (NTG)] in isolated mesenteric arterial rings from control and septic rats. Sepsis was induced by cecal ligation and puncture (CLP). A possible mechanism underlying CLP-induced alteration in vascular reactivity was also investigated with N omega-nitro-L-arginine (L-NNA 50 microM), methylene blue (MB 10 microM), and indomethacin (5 microM). In vivo, septic rats manifested two distinct hemodynamic phases, a hyperdynamic state during early (9 h after CLP) phase, followed by a hypodynamic state during late (18 h after CLP) phase. Therefore, we examined ex vivo vascular reactivity in these two phases. Results demonstrated that CLP operation caused hyporesponsiveness to contractile agents and hyperresponsiveness to vasodilator agents. After endothelium removal, most of the contractile responses were enhanced in both CLP-operated (9 and 18 h after operation) and sham-operated rats, whereas enhancement of high-K(+)-induced contraction was observed only in denuded rings from CLP 18-h rats. In addition, augmentation of relaxation induced by ACh at 9 or 18 h after CLP was abolished by N omega-nitro-L-arginine or MB but not by indomethacin. A possible mechanism responsible for alterations of vascular reactivity may be overproduction of nitric oxide (NO) which is blocked by L-NNA or MB.
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PMID:Alterations of ex vivo vascular reactivity in intraperitoneal sepsis. 753 57

Nitric oxide (NO), an important vasodilatory modulator of systemic and pulmonary vascular tone, is synthesized from L-arginine by the enzyme NO synthase in vascular endothelial and smooth muscle cells. L-Arginine analogs, such as N omega-nitro-L-arginine methyl ester (L-NAME), are competitive antagonists of NO synthase and inhibit NO synthesis. Group B streptococcus (GBS) causes pulmonary hypertension, hypoxemia, lung vascular injury, and reduced cardiac output in both human newborns and neonatal piglets. Lung vascular injury associated with prolonged GBS infusion in piglets may attenuate NO production and thus promote severe pulmonary hypertension. We studied the effect of the NOS inhibitor, L-NAME and the precursor of NO, L-arginine, on pulmonary and systemic hemodynamics during late-phase GBS sepsis in the piglet model. Neonatal piglets were anesthetized, ventilated with room air, and randomized to receive a continuous infusion of saline (n = 5) or GBS (n = 5) for 4 h. After 3 h of infusion, both groups received a bolus of L-NAME (3 mg/kg). Hemodynamic and gas exchange indices were measured at baseline, 30 min, and 3 h of infusion, and 30 min and 1 h after L-NAME treatment. L-NAME treatment caused 1) significant increases in mean pulmonary arterial pressure, pulmonary vascular resistance, mean systemic arterial pressure, and systemic vascular resistance for both groups; 2) a similar percentage of increase in pulmonary vascular resistance for the two groups; 3) greater reduction in cardiac output and SV in the GBS compared with the control group; and 4) no significant alterations in arterial partial pressure of oxygen or the difference between alveolar and arterial partial pressure of oxygen for either group.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of nitric oxide synthase inhibition during group B streptococcal sepsis in neonatal piglets. 753 3

Previous studies have yielded contradictory results about interrelations between endotoxin and endothelium-derived relaxing factor (EDRF). We tested the hypothesis that in vivo endotoxemia inhibits basal and/or agonist-mediated release of EDRF and nitric oxide (NO). EDRF bioactivity, NO production, and NO synthase (NOS) activity were measured in aorta from guinea pigs following 16 h of Escherichia coli endotoxemia (4 mg/kg endotoxin i.p.). Endothelium-dependent relaxation of aortic rings was studied under standard isometric conditions. Endotoxemia resulted in an 89% reduction in basal EDRF bioactivity and a 62% reduction in basal NO production in perfused aorta. EDRF bioactivity and NO production in response to the receptor-dependent agonists acetylcholine and ADP were significantly reduced in perfused aorta from endotoxemic animals. In contrast, endotoxin did not significantly inhibit EDRF bioactivity and NO production by the receptor-independent agonist A-23187. Aortic rings from endotoxemic animals likewise showed decreased vasodilator responses to acetylcholine and ADP but not to A-23187. Inducible (Ca2+ independent) NOS activity was not significantly different in control and endotoxin-treated animals. These findings indicate that prolonged endotoxemia resulted in diminution of release of EDRF, consistent with the interpretation that endotoxemia decreases basal and agonist-stimulated EDRF bioactivity and NO production with loss of endothelium-dependent vasodilator reserves during gram-negative sepsis.
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PMID:Release of EDRF and NO in ex vivo perfused aorta: inhibition by in vivo E. coli endotoxemia. 753 9

Sepsis, as a general inflammatory process, affects the whole organism, mainly because of the intense vasodilation and reduced perfusion pressures associated with it. The high mortality rates seen with sepsis are correlated with a reduction in mean arterial pressure. Therefore, the restoration of adequate arterial pressures is imperative. Nitric oxide (NO.) is at least partly responsible for the vasodilation. Inhibition of nitric oxide synthase (NOS) is, therefore, a logical approach for the treatment of sepsis. As with any other vasoconstrictive drug, NOS inhibitors are clinically indicated only in hyperdynamic sepsis. In animal models, their administration leads to an immediate restoration of blood pressure, accompanied by improved myocardial, pulmonary, and renal function. An increase in oxygen extraction prevents oxygen consumption from decreasing, despite a marked reduction in cardiac output to normal concentrations. In sepsis, virtually all regional blood flows are increased. In our experiments, no organ systems showed a reduction below preseptic baseline values when NOS inhibitors were administered. Furthermore, NOS inhibition did not cause an increase in lactate concentrations, indicating adequate nutritive organ blood flow. Consequently, NOS inhibitors seem to be beneficial and safe when administered under the right circumstances and in a controlled fashion.
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PMID:Use of nitric oxide synthase inhibitors in animal models of sepsis. 753 47

The liver plays important roles in metabolic and immune responses during sepsis. It is the major site of acute-phase protein synthesis and is responsible for the clearance of circulating pathogens. In addition to mediators such as cytokines and eicosanoids, numerous studies have emphasized the role of nitric oxide (NO.) in influencing hepatic function during sepsis. The induction and the distribution of inducible nitric oxide synthase in the liver, the regulation of the enzyme, and the functions of NO. in the liver are the subject of this review.
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PMID:Regulation and functions of nitric oxide in the liver in sepsis and inflammation. 753 50

The effects of L-arginine on the adrenergic responses to either electrical transmural stimulation or phenylephrine were studied in isolated endothelium-denuded strips of rat tail arteries treated with lipopolysaccharide for 6 h in vitro. L-arginine did not relax the strips precontracted by phenylephrine. However, the adrenergic contractions induced by electrical transmural stimulation were significantly inhibited by the addition of L-arginine. This inhibitory effect was reversed by NG-nitro-L-arginine (a nitric oxide synthase inhibitor) or methylene blue (a soluble guanylate cyclase inhibitor) but was not affected by hemoglobin (a scavenger of nitric oxide). These results indicate that the adrenergic neurogenic contractions may be directly modulated by nitric oxide derived from the sympathetic nerves and/or neighboring cells in the lipopolysaccharide-treated rat tail arteries, and the nitric oxide production may be associated with the reduction of sympathetic tone in sepsis.
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PMID:Selective inhibition of sympathetic nerve-mediated contraction by L-arginine in lipopolysaccharide-treated tail artery of rats. 753 6

1. We measured nitric oxide synthase activity in peripheral blood polymorphonuclear leucocytes from 10 patients with sepsis syndrome and 10 healthy subjects. 2. Synthase activity was significantly higher in patients with sepsis than in control subjects (1202 +/- 579 compared with 595 +/- 544 pmol of nitric oxide min-1 mg-1 of cell protein, P < 0.05). 3. Activity was greatest in those patients with the larger number of organ failures, although this failed to reach significance (1489 +/- 560 in patients with three or more organ failures and 843 +/- 404 pmol of nitric oxide min-1 mg-1 of cell protein in those with less than three, P = 0.11). 4. This study provides evidence for the role of overproduction of the vasodilator nitric oxide in sepsis syndrome.
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PMID:Nitric oxide synthase activity is increased in patients with sepsis syndrome. 753 46

Nitric oxide and vasoactive intestinal peptide (VIP) are potent vasodilators and postulated as inducers of hypotension. These mediators activate guanylate cyclase and adenylate cyclase, respectively, with subsequent biosynthesis of cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) producing vascular smooth muscle relaxation and vasodilatation. Cyclic nucleotides and VIP were evaluated during Escherichia coli septicemia in two groups of rabbits; 1) sepsis alone and 2) sepsis and a competitive inhibitor of nitric oxide synthase, NG-monomethyl-L-arginine. Arterial blood was obtained for determination of bacteremia, lactic acidemia, nucleotides, nitrites, and VIP levels. Significant bacteremia, endotoxemia, tachycardia, lactic acidosis, and hypotension occurred in all animals (P < 0.005). Circulating blood levels of cGMP, nitrites, cAMP, and VIP (P < 0.005) increased with development of shock. The NG-monomethyl-L-arginine treated animals had less cGMP, nitrites, cAMP, and VIP produced (P < 0.01). Plasma cGMP levels remained stable, suggesting that stimulated phagocytes in whole blood were responsible for increased cGMP levels. Infusion of VIP produced profound hypotension and lactic acidemia. Results of these experiments provide definitive evidence that nitric oxide and VIP are mediators during septic shock and their messengers are cGMP and cAMP, respectively. In addition, phagocytic stimulation with increased production of cGMP may initiate shock, with these mediators acting synergistically to prolong hypotension.
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PMID:Cyclic nucleotides and vasoactive intestinal peptide production in a rabbit model of Escherichia coli septicemia. 753 47

Nitric oxide (NO) is an important mediator of the hemodynamic effects of sepsis; however, its microcirculatory effects are unknown. To determine the role of NO in the small intestinal (SI) microcirculation, an intact SI loop was exteriorized from decerebrate rats into a controlled Krebs' bath. Bacteremic rats received 10(9) Escherichia coli intravenously. Videomicroscopy was used to measure arteriolar diameters (A1, A3) and optical Doppler velocimetry to quantitate flow. In controls, topical NO synthase (NO-S) substrate L-arginine (L-ARG; 10(-4) M) did not affect diameters or flow. Inhibition of NO-S by N omega-nitro-L-arginine methyl ester (L-NAME; 10(-4) M) caused constriction (A1 = -18%; A3 = -24% from baseline diameter) and reduced A1 flow by 62%. These alterations were similar to bacteremic controls (A1 = -20%; A3 = -18%; A1 flow = -42%), despite the increased cardiac output (+21%). L-NAME treatment of bacteremic rats resulted in further constriction (A1 = -31%; A3 = -32%) and decreased A1 flow (-75%). Topical L-ARG (10(-4) M) ameliorated constriction (A1 = -6%; A3 = +7%) and improved blood flow (-5%) during bacteremia. We conclude that: 1) NO is important for basal SI microvascular tone; 2) bacteremia causes SI arteriolar constriction and hypoperfusion; 3) NO-S inhibition during sepsis may exacerbate SI vasoconstriction and hypoperfusion.
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PMID:Role of nitric oxide in the small intestinal microcirculation during bacteremia. 753 19

To test the hypothesis that release of endothelium-derived relaxing factor/nitric oxide is inhibited by Gram-negative lipopolysaccharide (LPS; endotoxin), we examined endothelium-independent and endothelium-dependent vasodilator agents in aortic vascular smooth muscle isolated from guinea pigs 4 h after injection of saline (controls) or induction of Escherichia coli endotoxemia. LPS significantly inhibited vasodilator responses to the endothelium-dependent agonists acetylcholine (ACh; 10(-10)-10(-5) M) and ADP (10(-8)-10(-5) M). However, LPS did not affect vasodilator responses to the endothelium-independent agonist nitroprusside (10(-10)-10(-4) M). The nitric oxide synthase (NOS) inhibitor N gamma-nitro-L-arginine methyl ester (L-NAME) inhibited the vasodilator response to ACh; whereas, the cyclooxygenase inhibitor indomethacin (INDO) did not reduce vasodilator effects of ACh. Neither L-NAME nor INDO affected the vasodilator effects of nitroprusside in LPS or control vessels. In contrast, L-NAME converted the vasodilator action of ADP to a vasoconstrictor response that was blocked individually by INDO and the thromboxane synthase inhibitor dazoxiben, suggesting that ADP releases NO and also the vasoconstrictor and platelet aggregating eicosanoid thromboxane A2. These findings suggest that acute (4 h) endotoxemia inhibits function of the constitutive isoform of NOS in vascular endothelial cells. Since L-NAME unmasked a vasoconstrictor action of the endogenous purinoceptor agonist ADP, pharmacologic agents that inhibit NOS may exacerbate LPS-induced inhibition of endothelial NOS; this series of events could lead to diminution of vasodilator reserves and perhaps to augmentation of platelet aggregation during Gram-negative sepsis.
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PMID:Inhibition of endothelium-dependent vasodilation by Escherichia coli endotoxemia. 753 38


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