Navegando por Palavras-chave "nitrite"

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    Dietary nitrate supplementation and exercise tolerance in patients with heart failure with reduced ejection fraction
    (Amer Physiological Soc, 2017) Hirai, Daniel Müller [UNIFESP]; Zelt, Joel T.; Jones, Joshua H.; Castanhas, Luiza G.; Bentley, Robert F.; Earle, Wendy; Staples, Patti; Tschakovsky, Michael E.; McCans, John; O'Donnell, Denis E.; Neder, J. Alberto
    Endothelial dysfunction and reduced nitric oxide (NO) signaling are key abnormalities leading to skeletal muscle oxygen delivery-utilization mismatch and poor physical capacity in patients with heart failure with reduced ejection fraction (HFrEF). Oral inorganic nitrate supplementation provides an exogenous source of NO that may enhance locomotor muscle function and oxygenation with consequent improvement in exercise tolerance in HFrEF. Thirteen patients (left ventricular ejection fraction <= 40%) were enrolled in a double-blind, randomized crossover study to receive concentrated nitrate-rich (nitrate) or nitrate-depleted (placebo) beetroot juice for 9 days. Low- and high-intensity constant-load cardiopulmonary exercise tests were performed with noninvasive measurements of central hemodynamics (stroke volume, heart rate, and cardiac output via impedance cardiography), arterial blood pressure, pulmonary oxygen uptake, quadriceps muscle oxygenation (near-infrared spectroscopy), and blood lactate concentration. Ten patients completed the study with no adverse clinical effects. Nitrate-rich supplementation resulted in significantly higher plasma nitrite concentration compared with placebo (240 +/- 48 vs. 56 +/- 8 nM, respectively
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    Effect of cyclosporin A on nitric oxide production in cultured LLC-PK1 cells
    (Marcel Dekker Inc, 2001-01-01) Lima, R.; Serone, A. P.; Schor, N.; Higa, EMS; Universidade Federal de São Paulo (UNIFESP)
    The effect of Cyclosporin A on nitric oxide production was studied in cultured LLC- PK1 cells. for this purpose the cells were incubated with vehicle (olive oil, 10 mug/ml in DMSO), Cyclosporin A (CsA, 10 mug/ml), tumor necrosis factor (TNF-alpha, 150 U/ml) + interferon (IFN-gamma, 500 U/ml) to upregulate NOS synthesis, and therefore, NO production (used as a positive control), or CsA + TNF-alpha + IFN-gamma. After 72 hours the culture medium was collected and nitrite was determined by the Griess method. the results were normalized to the protein harvested from these cells as measured by the Lowry method. Viability was determined by the exclusion of the fluorescent dyes (acridine orange and ethidium bromide). Intracellular calcium was measured spectrophotometrically using the fluorescent calcium indicator fura-2 AM. in CsA treated cells, the nitrite (pmoles/mg of protein) was decreased when compared to control (12.8 +/- 0.5 vs. 18.3 +/- 0.6; p < 0.05; both n = 8). TNF- + IFN-gamma increased the nitrite synthesis (52.0 +/- 0.2; p < 0.05 vs. control; n = 6). This effect was decreased significantly by the simultaneous treatment with CsA (38.8 +/- 0.3; p < 0.05; n = 6). Cell viability in CsA group was decreased when compared to the cdntrol (84.7 +/- 0.2% vs. 93.6 +/- 0,1%; p < 0.05: both n = 10). TNF- +/- IFN-gamma had no effect on viability (93.0 +/- 0.3%; n = 10). However, when combined with CsA, viability was decreased relative to the control (85.0 +/- 0.2%; p < 0.05; n = 10). Acute (1 h) or chronic (72 h) treatment of LLC- PK1 cells with CsA had no effect on basal calcium levels.Our results demonstrate a reduced level of nitric oxide production in LLC- PK1 cells treated with CsA. There was no effect of the drug on intracellular calcium levels, however CsA treatment did reduce cellular viability. We suggest that, in part, the decreased levels of NO production are a secondary consequence of direct cell damage. However, CsA may also be exerting direct effects on NO synthesis through its interactions with both iNOS and cNOS. These results also provide a dual mechanism of action for CsA induced nephrotoxicity, that is, direct cell damage and interference with the NO system within the nephron.