Increased plasma nitrite level in cardiac failure

Acute Effects of Dietary Nitrate on Exercise Tolerance, Muscle Oxygenation, and Cardiovascular Function in Patients With Peripheral Arterial Disease

Previous studies have used supplements to increase dietary nitrate intake in clinical populations. Little is known about whether effects can also be induced through vegetable consumption. Therefore, the aim of this study was to assess the impact of dietary nitrate, through nitrate-rich vegetables (NRV) and beetroot juice (BRJ) supplementation, on plasma nitrate and nitrite concentrations, exercise tolerance, muscle oxygenation, and cardiovascular function in patients with peripheral arterial disease. In a randomized crossover design, 18 patients with peripheral arterial disease (age: 73 ± 8 years) followed a nitrate intake protocol (∼6.5 mmol) through the consumption of NRV, BRJ, and nitrate-depleted BRJ (placebo). Blood samples were taken, blood pressure and arterial stiffness were measured in fasted state and 150 min after intervention. Each intervention was followed by a maximal walking exercise test to determine claudication onset time and peak walking time. Gastrocnemius oxygenation was measured by near-infrared spectroscopy. Blood samples were taken and blood pressure was measured 10 min after exercise. Mean plasma nitrate and nitrite concentrations increased (nitrate; Time × Intervention interaction; p < .001), with the highest concentrations after BRJ (494 ± 110 μmol/L) compared with NRV (202 ± 89 μmol/L) and placebo (80 ± 19 μmol/L; p < .001). Mean claudication onset time and peak walking time did not differ between NRV (413 ± 187 s and 745 ± 220 s, respectively), BRJ (392 ± 154 s and 746 ± 176 s), and placebo (403 ± 176 s and 696 ± 222 s) (p = .762 and p = .165, respectively). Gastrocnemius oxygenation, blood pressure, and arterial stiffness were not affected by the intervention. NRV and BRJ intake markedly increase plasma nitrate and nitrite, but this does not translate to improved exercise tolerance, muscle oxygenation, and/or cardiovascular function.

İnvestigation of endothelial dysfunction in children with acute rheumatic fever

Background:

Acute rheumatic fever (ARF) is an important cause of valvular heart disease in children. Endothelial dysfunction plays an important role in the pathogenesis of valvular heart diseases. The role of endothelial dysfunction in valvular heart diseases due to ARF is not exactly known. In ARF, autoimmune injury, inflammation, oxidative stress, and impairment of nitric oxide in valvular endothelium may be the causes of endothelial dysfunction. The purpose of this study is to evaluate endothelial dysfunction and arterial stiffness in children with ARF.

Materials and Methods:

Thirty-six patients diagnosed with ARF (the mean age was 11.80 ± 2.82 years) and 36 volunteered individuals with similar age, sex, and body mass index were included in the study. The study groups were compared in terms of M-mode echocardiography parameters, carotid arterial strain (CAS), beta-stiffness index (βSI), and flow-mediated dilation (FMD).

Results:

In patients with ARF, there was a decrease in FMD% (10.36 ± 7.26 and 12.76 ± 4.59; P < 0.001) compared to the control group. In addition, CAS (0.16 ± 0.06 and 0.18 ± 0.08; P = 0.44) and βSI (3.65 ± 1.61 and 3.57 ± 2.38; P = 0.24) were similar in the patient and the control groups. Furthermore, no correlation was detected between decreased FMD value and mitral regurgitation (r = −0.07; P = 0.66), aortic regurgitation (r = −0.04; P = 0.78), CAS (r = −0.08; P = 0.61), and βSİ (r = −0.20; P = 0.22).

Conclusion:

In our study, a decrease in FMD value, which is a marker of endothelial dysfunction, was found in children with rheumatic carditis.

Molecular mechanisms in endothelial regulation of cardiac function

Endothelium is now recognized as a massive, regionally specific, multifunctional organ. Given its strategic anatomic location between the circulating blood components and the vascular smooth muscle or the cardiac muscle, it is a biologically significant interface whose dysfunction can be a critical factor in various pathological conditions. Two types of endothelial cells are recognized in the heart, the endocardial endothelial (EE) cells and the microvascular endothelial cells (MVE). Both produce common autacoids and share similar roles in signal transduction induced by neurotransmitters, hormones or mechanical stimuli. They are however two distinct cell populations with dissimilar embryological origin, cytoskeletal organization, receptor mediated functions and electrophysiological properties. Both the MVE and EE are modulators of cardiac performance. Myocardial contraction may be modulated by cardioactive agents such as nitric oxide, prostanoids, endothelin, natriuretic peptides, angiotensin II, kinins, reactive oxygen species and adenyl purines released from the cardiac endothelium. Two mechanisms have been proposed for the signal transduction from EE to the underlying myocytes: stimulus-secretion-contraction coupling and blood-heart barrier. Nitric oxide, bradykinin and myofilament desensitizing agent are probably important in short-term regulation of myocardial functions. Endothelin and Angiotensin II are probably involved in long-term regulation. Besides its sensory function and paracrine modulation of myocardial performance, EE as a blood-heart barrier could be of significance for the ionic homeostasis of the cardiac interstitium. In cardiac diseases, the damage to EE or MVE leading to failure of the endothelial cells to perform its regulatory and modulator functions may have serious consequences. A better understanding of the endothelial signaling pathways in cardiac physiology and pathophysiology may lead to the development of novel therapeutic strategies.