Treatment with new organic nitrites in pulmonary hypertension of acute experimental pulmonary embolism

Oxidative stress in acute pulmonary embolism: emerging roles and therapeutic implications

Oxidative stress is an imbalance between the body's reactive oxygen species and antioxidant defense mechanisms. Oxidative stress is involved in the development of several cardiovascular diseases, such as pulmonary hypertension, atherosclerosis, and diabetes mellitus. A growing number of studies have suggested the potential role of oxidative stress in the pathogenesis of pulmonary embolism. Biomarkers of oxidative stress in pulmonary embolism have also been explored, such as matrix metalloproteinases, asymmetric dimethylarginine, and neutrophil/lymphocyte ratio. Here, we comprehensively summarize some oxidative stress mechanisms and biomarkers in the development of acute pulmonary embolism and summarize related treatments based on antioxidant stress to explore effective treatment strategies for acute pulmonary embolism.

Diagnostic values of serum BNP, PTX3, and VEGF in acute pulmonary embolism complicated by pulmonary artery hypertension and their correlations with severity of pulmonary artery hypertension

OBJECTIVE

This paper aimed to unveil the diagnostic values of serum brain natriuretic peptide (BNP), pentraxin 3 (PTX3), and vascular endothelial growth factor (VEGF) in acute pulmonary embolism complicated by pulmonary artery hypertension (APE-PAH) and their correlations with severity of PAH.

METHODS

A total of 153 patients with APE were selected for our study and divided into the PAH and Non-PAH groups according to the measurement of pulmonary artery pressure by echocardiography. Serum BNP levels were measured by chemiluminescence immunoassay, and serum PTX3 and VEGF levels were appraised by ELISA. The predictive values of BNP, PTX3, and VEGF for APE-PAH were evaluated by applying the receiver operating characteristic (ROC) curve. Spearman test was implemented to correlate BNP, PTX3, and VEGF with the severity of PAH.

RESULTS

Higher serum levels of BNP, PTX3, and VEGF were observed in the PAH group versus the Non-PAH group (p < .05). ROC curve analysis indicated that BNP, PTX3, and VEGF had acceptable diagnostic value for predicting APE-PAH. Higher serum levels of BNP, PTX3, and VEGF were witnessed in the moderate and severe PAH groups in contrast to the mild PAH group (p < .05), and the levels of these parameters were elevated in the severe PAH group versus the moderate PAH group (p < .05). Spearman correlation analysis signified that serum BNP (r = 0.377), PTX3 (r = 0.488), and VEGF (r = 0.575) levels were positively correlated with the severity of PAH in APE-PAH patients.

CONCLUSION

Serum BNP, PTX3, and VEGF levels are significantly elevated in APE-PAH patients. Serum BNP, PTX3, and VEGF levels are of clinical value in the diagnosis of APE-PAH patients, and serum BNP, PTX3, and VEGF levels are positively correlated with the severity of PAH and can be used as predictors of the severity of PAH.

NO-Donation Increases Visceral Circulation in a Porcine Model of Abdominal Hypertension

Intraabdominal hypertension (IAH) is negative for outcome after intensive care. Little research has focused on medical intervention to improve visceral circulation during IAH. A nitric oxide (NO)-donor was compared with placebo in 25 pigs; each pig was randomized into three groups: PDNO (NO-donor), Control (placebo), or Sham. IAH was induced by CO2 insufflation to 30 mmHg. Sham group had surgical preparation only. Blood gases, invasive venous and arterial blood pressure, intestinal microcirculation and superior mesenteric blood flow were measured. The PDNO group had significantly increased intestinal microcirculation compared with Controls during IAH (last hour, P = 0.009). The mean arterial pressure and abdominal perfusion pressures (APP) were decreased, and the cardiac index were increased in the PDNO group. Also, systemic and pulmonary vascular resistances were lower in the PDNO group compared with Controls. These experimental findings indicate that NO should be further explored with potential application to improve intestinal microcirculation in IAH patients.

Pulmonary Vasodilation by Intravenous Infusion of Organic Mononitrites Of 1,2-Propanediol in Acute Pulmonary Hypertension Induced by Aortic Cross Clamping and Reperfusion: A Comparison With Nitroglycerin in Anesthetized Pigs

INTRODUCTION

Suprarenal aortic cross clamping (SRACC) and reperfusion may cause acute pulmonary hypertension and multiple organ failure.

HYPOTHESIS

The organic mononitrites of 1,2-propanediol (PDNO), an nitric oxide donor with a very short half-life, are a more efficient pulmonary vasodilator and attenuator of end-organ damage and inflammation without significant side effects compared with nitroglycerin and inorganic nitrite in a porcine SRACC model.

METHODS

Anesthetized and instrumented domestic pigs were randomized to either of four IV infusions until the end of the experiment (n = 10 per group): saline (control), PDNO (45 nmol kg min), nitroglycerin (44 nmol kg min), or inorganic nitrite (a dose corresponding to PDNO). Thereafter, all animals were subjected to 90 min of SRACC and 10 h of reperfusion and protocolized resuscitation. Hemodynamic and respiratory variables as well as blood samples were collected and analysed.

RESULTS

During reperfusion, mean pulmonary arterial pressure and pulmonary vascular resistance were significantly lower, and stroke volume was significantly higher in the PDNO group compared with the control, nitroglycerin, and inorganic nitrite groups. In parallel, mean arterial pressure, arterial oxygenation, and fraction of methaemoglobin were similar in all groups. The serum concentration of creatinine and tumor necrosis factor alpha were lower in the PDNO group compared with the control group during reperfusion.

CONCLUSIONS

PDNO was an effective pulmonary vasodilator and appeared superior to nitroglycerin and inorganic nitrite, without causing significant systemic hypotension, impaired arterial oxygenation, or methaemoglobin formation in an animal model of SRACC and reperfusion. Also, PDNO may have kidney-protective effects and anti-inflammatory properties.

The State of the Nitric Oxide Cycle in Respiratory Tract Diseases

This review describes the unique links of the functioning of the nitric oxide cycle in the respiratory tract in normal and pathological conditions. The concept of a nitric oxide cycle has been expanded to include the NO-synthase and NO-synthase-independent component of its synthesis and the accompanying redox cascades in varying degrees of reversible reactions. The role of non-NO-synthase cycle components has been shown. Detailed characteristics of substrates for the synthesis of nitric oxide (NO) in the human body, which can be nitrogen oxides, nitrite and nitrate anions, and organic nitrates, as well as nitrates and nitrites of food products, are given. The importance of the human microbiota in the nitric oxide cycle has been shown. The role of significant components of nitrite and nitrate reductase systems in the nitric oxide cycle and the mechanisms of their activation and deactivation (participation of enzymes, cofactors, homeostatic indicators, etc.) under various conditions have been determined. Consideration of these factors allows for a detailed understanding of the mechanisms underlying pathological conditions of the respiratory system and the targeting of therapeutic agents. The complexity of the NO cycle with multidirectional cascades could be best understood using dynamic modeling.

A Comparative Study of Inhaled Nitric Oxide and an Intravenously Administered Nitric Oxide Donor in Acute Pulmonary Hypertension

Purpose

Inhaled nitric oxide (iNO) selectively vasodilates the pulmonary circulation but the effects are sometimes insufficient. Available intravenous (iv) substances are non-selective and cause systemic side effects. The pulmonary and systemic effects of iNO and an iv mono-organic nitrite (PDNO) were compared in porcine models of acute pulmonary hypertension.

Methods

In anesthetized piglets, dose–response experiments of iv PDNO at normal pulmonary arterial pressure (n=10) were executed. Dose–response experiments of iv PDNO (n=6) and iNO (n=7) were performed during pharmacologically induced pulmonary hypertension (U46619 iv). The effects of iv PDNO and iNO were also explored in 5 mins of hypoxia-induced increase in pulmonary pressure (n=2-4).

Results

PDNO (15, 30, 45 and 60 nmol NO kg⁻¹ min⁻¹ iv) and iNO (5, 10, 20 and 40 ppm which corresponded to 56, 112, 227, 449 nmol NO kg⁻¹ min⁻¹, respectively) significantly decreased the U46619-increased mean pulmonary arterial pressure (MPAP) and pulmonary vascular resistance (PVR) to a similar degree without significant decreases in mean arterial pressure (MAP) or systemic vascular resistance (SVR). iNO caused increased levels of methemoglobin. At an equivalent delivered NO quantity (iNO 5 ppm and PDNO 45 nmol kg⁻¹ min⁻¹ iv), PDNO decreased PVR and SVR significantly more than iNO. Both drugs counteracted hypoxia-induced pulmonary vasoconstriction and they decreased the ratio of PVR and SVR in both settings.

Conclusion

Intravenous PDNO was a more potent pulmonary vasodilator than iNO in pulmonary hypertension, with no severe side effects. Hence, this study supports the potential of iv PDNO in the treatment of acute pulmonary hypertension.