Effects of selective iNOS inhibition on systemic hemodynamics and mortality rate on endotoxic shock in streptozotocin-induced diabetic rats

Preclinical studies of NOS inhibitor T1059 vasopressor activity on the models of acute hemorrhagic shock in rats and dogs

The development of new effective and safe vasopressors is one of the ways to increase the effectiveness of the treatment of hypotensive disorders, the severe forms of which remain a common cause of death in all countries of the world. Previously, we synthesized the original compound T1059, a selective inhibitor of eNOS/iNOS which has a pronounced vasoconstrictive effect. Here we show its vasopressor activity in models of the early stage of acute hemorrhagic shock in rats and dogs, as part of preclinical studies. The results indicate NOS inhibitor T1059 as a potent long-acting vasopressor. Its single parenteral administration in sufficiently safe doses (1/50–1/9 LD₁₀), caused in rats and dogs a rapid increase in vascular tone, accompanied by a prolonged hypertensive effect (within 90–120 min in rats, and within 115 min in dogs). The repeated administration of T1059 at low doses (1/3 of the first dose) made it possible to considerably (by at least 60 min) prolong a significant vasopressor effect. In all schemes, T1059 administration considerably inhibited the development of threatening cardiorespiratory disorders and significantly (p = 0.0026–0.0098) increased the short-term survival of experimental animals, formally extending the duration of the “golden hour” by 2 times. These data indicate that NOS inhibitors and, in particular, compound T1059, are able to create new opportunities in the treatment of hypotensive disorders, including the provision of assistance at the prehospital stage of treatment of such pathologies.

Effect of NOS Inhibitors and Anticoagulants on Nitric Oxide Production in a Tissue-factor Induced Rat DIC Model

BACKGROUND/AIM

We examined the mechanism of nitric oxide (NO) production in a tissue-factor (TF)-induced disseminated intravascular coagulation (DIC) model in rats, using inducible nitric oxide synthase (iNOS) inhibitor (L-NIL), endothelial nitric oxide synthase (eNOS) inhibitor (L-NAME), Factor Xa inhibitor (DX-9065a), and thrombin inhibitor argatroban.

MATERIALS AND METHODS

Experimental DIC was induced by sustained infusion of 3.75 U/kg TF for 4 h via the tail vein. We then investigated the effect of these four agents on TF-induced DIC.

RESULTS

Administration of L-NIL or L-NAME during induction of TF-induced DIC did not affect hemostatic markers, whereas elevated plasma levels of NO metabolites (NOX) were significantly suppressed by co-administration of L-NAME. A significant increase in eNOS-mRNA expression was observed in the TF-induced DIC model. Argatroban almost completely suppressed eNOS-mRNA expression.

CONCLUSION

eNOS plays an important role in the NO production in the TF-induced DIC, and thrombin is a key stimulant of eNOS-mRNA expression in this model.

Vascular endothelial dysfunction and pharmacological treatment

The endothelium exerts multiple actions involving regulation of vascular permeability and tone, coagulation and fibrinolysis, inflammatory and immunological reactions and cell growth. Alterations of one or more such actions may cause vascular endothelial dysfunction. Different risk factors such as hypercholesterolemia, homocystinemia, hyperglycemia, hypertension, smoking, inflammation, and aging contribute to the development of endothelial dysfunction. Mechanisms underlying endothelial dysfunction are multiple, including impaired endothelium-derived vasodilators, enhanced endothelium-derived vasoconstrictors, over production of reactive oxygen species and reactive nitrogen species, activation of inflammatory and immune reactions, and imbalance of coagulation and fibrinolysis. Endothelial dysfunction occurs in many cardiovascular diseases, which involves different mechanisms, depending on specific risk factors affecting the disease. Among these mechanisms, a reduction in nitric oxide (NO) bioavailability plays a central role in the development of endothelial dysfunction because NO exerts diverse physiological actions, including vasodilation, anti-inflammation, antiplatelet, antiproliferation and antimigration. Experimental and clinical studies have demonstrated that a variety of currently used or investigational drugs, such as angiotensin-converting enzyme inhibitors, angiotensin AT1 receptors blockers, angiotensin-(1-7), antioxidants, beta-blockers, calcium channel blockers, endothelial NO synthase enhancers, phosphodiesterase 5 inhibitors, sphingosine-1-phosphate and statins, exert endothelial protective effects. Due to the difference in mechanisms of action, these drugs need to be used according to specific mechanisms underlying endothelial dysfunction of the disease.

Cardiopulmonary Profile in Streptozotocin-Induced Type 1 Diabetic Rats during Systemic Endotoxemia

This study was designed to determine the severity of cardiopulmonary dysfunction during systemic endotoxemia in type 1 diabetes. Thirty-two adult male Wistar rats were randomly assigned to a control group or to a group treated with streptozotocin (STZ) to create an animal model of type 1 diabetes. Survival time and cardiovascular parameters were continually monitored in urethane anaesthetized animals receiving intravenous infusion of endotoxin (lipopolysaccharide (LPS)) or saline. We also determined arterial blood gases, lung injury, and tumor necrosis factor-alpha (TNF- α ) levels in serum and bronchoalveolar lavage fluid. Before LPS administration, the mean arterial pressure in STZ rats was significantly higher than that in normal rats. After LPS injection, the heart rate drop significantly in STZ rats than that in the control group. Also, the increased levels of TNF- α in serum and lavage fluid after LPS treatment were significantly higher in STZ rats than those in normal rats. Survival time in STZ rats was shorter than that in normal rats after LPS application. Albumin content, wet/dry weight ratio of lung, and lung injury were indistinguishable between STZ and normal rats. These results indicate that the cardiopulmonary change which occurs during LPS-induced endotoxemia is minor in STZ-induced diabetic rats.

Rosmarinic acid protects against experimental sepsis by inhibiting proinflammatory factor release and ameliorating hemodynamics

The present study was to investigate the effects of rosmarinic acid (RA) in cultured RAW264.7 cells and experimental model of sepsis induced by cecal ligation and puncture in rats and the potential mechanism. Results showed that RA concentration dependently down-regulated the levels of TNF-alpha, IL-6, and high-mobility group box 1 protein in LPS-induced RAW264.7 cells, inhibited the IkappaB kinase pathway, and modulated nuclear factor-kappaB. Intravenous injection of RA alone or in combination with imipenem reduced cecal ligation and puncture-induced lethality in rats. In addition, serum levels of TNF-alpha, IL-6, high-mobility group box 1 protein, triggering receptor expressed on myeloid cells, and endotoxin were down-regulated; in contrast, serum level of IL-10 was up-regulated. Amelioration of hemodynamics and decrease in serum enzyme activities and myeloperoxidase in lung, liver, and small intestine were also observed after RA injection. These data indicate that the antisepsis effect of RA was mediated by decreasing local and systemic levels of a wide spectrum of inflammatory mediators. This article provides the first evidence that RA has the capacity to inactivate inflammatory response in sepsis. The anti-inflammatory mechanism of RA may inhibit activation of the nuclear factor- kappaB pathway by inhibiting IkappaB kinase activity.

Statins for all: the new premed?

The use of statins is widespread and many patients presenting for surgery are regularly taking them. There is evidence that statins have beneficial effects beyond those of lipid lowering, including reducing the perioperative risk of cardiac complications and sepsis. This review addresses the cellular mechanisms by which statins may produce these effects. Statins appear to have actions on vascular nitric oxide through the balance of inducible and endothelial nitric oxide synthase. The clinical evidence for these benefits is also briefly reviewed with the objective of clarifying the current status of statin use in the perioperative period. There is reasonably strong evidence that patients already taking statins should continue on them perioperatively. However, the evidence for the prophylactic use of statins perioperatively is weak and lacks prospective controlled studies.

Rifle classification for predicting in-hospital mortality in critically ill sepsis patients

Severe sepsis and septic shock, often complicated by acute kidney injury (AKI), are the most common causes of mortality in noncoronary intensive care units (ICUs). This study investigates the outcomes of critically ill patients with sepsis and elucidates the association between prognosis and risk of renal failure, injury to the kidney, failure of kidney function, loss of kidney function, and end-stage renal failure (RIFLE) classification. A total of 121 sepsis patients were admitted to ICU from June 2003 to January 2004. Forty-seven demographic, clinical, and laboratory variables were prospectively recorded for post hoc analysis as predictors of survival on the first day of ICU admission. Overall in-hospital mortality rate was 47.9%. Mortality was significantly associated (chi-square for trend; P < 0.001) with RIFLE classification. Septic shock, RIFLE category, and number of organ system failures on the first day of ICU admission were independent predictors of hospital mortality according to forward conditional logistic regression. The severity of RIFLE classification correlated with organ system failure number and Acute Physiology and Chronic Health Evaluation (APACHE) II to IV and sequential organ failure assessment scores. Cumulative survival rates at 6-month follow-up after hospital discharge significantly (P < 0.05) differed between non-AKI versus RIFLE injury, non-AKI versus RIFLE failure (RIFLE-F), and RIFLE risk versus RIFLE F. At 6-month follow-up, full recovery of renal function was noted in 85% of surviving patients with AKI (RIFLE risk, RIFLE injury, and RIFLE-F). In conclusion, these findings are consistent with a role for RIFLE classification in accurately predicting in-hospital mortality and short-term prognosis in ICU sepsis patients.

Effects of the cannabinoid antagonist AM281 on systemic hemodynamics and mortality rate in streptozotocin-induced diabetic rats with endotoxic shock: comparison between non-diabetic and diabetic rats

PURPOSE

On the basis of previous findings that the anandamide antagonist AM281, an endogenous cannabinoid receptor antagonist, could restore the hemodynamic and cerebral blood flow changes and improve the mortality rate in non-diabetic rats during sepsis, this study was conducted to examine whether AM281 could restore the hemodynamic variables and improve the mortality rate in streptozotocin-induced diabetic rats during sepsis.

METHODS

The study was designed to include three sets of experiments, each set of experiment being conducted in both diabetic and non-diabetic animals: (1) measurement of changes in systemic hemodynamics and carotid artery blood flow, (2) measurement of biochemical variables and (3) assessment of mortality rate. Systemic hemodynamics, carotid artery blood flow changes and biochemical variables were assessed at pre-treatment and 1, 2 and 3 h after the treatment was performed.

RESULTS

In both non-diabetic and diabetic rats, administration of lipopolysaccharide (LPS) induced a reduction in hemodynamic variables, these reductions being greater in diabetic than in non-diabetic rats. In diabetic rats, administration of AM281 could only partially prevent these hemodynamic changes, these changes being insufficient to elevate these variables to control values. Significant differences were observed in mortality rates at 6 and 12 h between non-diabetic and diabetic groups with the same treatment. At 12 h, only non-diabetic AM281 group rats were still alive (mortality rate 50%).

CONCLUSION

Administration of AM281 only partially prevented the hemodynamic, biochemical and carotid artery blood flow changes associated with LPS-induced septicemia in diabetic rats, as compared with non-diabetic rats in whom these changes were prevented to a greater extent.