Nitric Oxide Availability Research Articles

Diabetes and obesity: A debate on bariatric interventions and its implications

In this editorial, we comment on an article by Tang et al published in the World Journal of Diabetes . Obesity and diabetes are two pathological situations that are intrinsically related. Neither lifestyle changes nor pharmacological treatments have achieved diabetes remission. From this perspective, bariatric surgery has been widely used as an approach for weight loss in obese patients and as a strategy to promote metabolic modulation. The main effects of bariatric surgery involve direct action in improving cardiovascular function and endothelial function and reducing insulin resistance, leading to diabetes remission in the short term following surgery. In this context, it has been observed that hormones from the gastrointestinal tract and endothelium play a prominent role in this process. By reversing endothelial dysfunction, it is possible to balance pro-inflammatory cytokine production, improving the availability of nitric oxide and inhibiting vascular oxidative stress. Furthermore, it can be considered an efficient anti-inflammatory strategy, alleviating interferon-gamma-mediated adipose tissue inflammation. The current challenge must be to unravel the pathophysiological mechanisms and potential targets for treating metabolic diseases.

Increased Nitric Oxide Availability: The Explanation for Recent Improvements in Saphenous Vein Graft Patency?

Increased Nitric Oxide Availability: The Explanation for Recent Improvements in Saphenous Vein Graft Patency?

L-arginine, aminoguanidine and mesenchymal stem cells reduce the level of endoplasmic reticulum stress markers and D-dimer in the lungs of mice with antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by damage to the intima of the microcirculatory blood vessels as a result of the formation of autoimmune antibodies to phospholipids of cell membranes. Recent data indicate a possible link between the occurrence of autoimmune diseases and endoplasmic reticulum stress, impaired nitric oxide availability, high plasma D-dimer level. The aim of the study was to estimate the effect of nitric oxide synthesis modulators L-arginine and aminoguanidine, and mesenchymal stem cells on the level of inositol-requiring enzyme-1a (IRE-1a), glucose-regulated protein 78 (GRP-78) as ER stress markers, and the level of D-dimer in the lung tissue of female BALB/c line mice with experimental APS induced with cardiolipin administration. 30 experimental animals were divided into five groups: 1 – control animals; 2 – mice with APS; 3 – mice with APS, injected intraperitoneally with L-arginine hydrochloride (25 mg/kg) and aminoguanidine (10 mg/kg); 4 – mice with APS, injected intraperitoneally with stem cells (5×106/kg); 5 – mice with APS, injected with L-arginine hydrochloride, aminoguanidine and stem cells in combination. After 10 days post APS formation animals were removed from the experiment, proteins were extracted from the lung tissue and their level was determined with Western blotting. It was established that in group with APS the levels of IRE-1, GRP-78 and D-dimer were substantially increased as compared to the control group. After separate administration of both arginine with aminoguanidine and MSC, as well as with their combined use, the level of IRE-1, GRP-78 and D-dimer decreased compared to the indices in animals with induced APS. The obtained data indicated that this effect is probably due to the reduction of ER stress through iNOS inhibition and the anti-inflammatory action of MSCs. Keywords: aminoguanidine, antiphospholipid syndrome, D-dimer, endoplasmic reticulume stress, GRP-78, IRE-1, L-arginine, lung, mesenchymal stem cells

Pharmacological evaluation of a new nanoformulation in the erectile tissue of rabbits and humans

The failure of achieving a penile erection for satisfactory sexual intercourse is known as erectile dysfunction (ED). The primary mediator for penile erection is nitric oxide (NO). ED is often associated with endothelial/nitrergic dysfunction characterized by a reduction of the bioavailability of NO. Phosphodiesterase-5 inhibitors (PDE-5Is) clinical efficacy in the treatment of ED depends on the integrity of the NO-sGC-PKG pathway. In the present study, we probed the effect of sodium nitroprusside incorporated into mesoporous silica nanoparticles (MPSi-NP), which traps cyanide and slowly releases NO. MPSi-NP induced a maximal relaxation of 92.8 ± 5.2% in rabbit corpora cavernosa (RbCC), blunted by a soluble guanylate cyclase (sGC) inhibitor and blockers of calcium-dependent potassium channels. MPSi-NP abolished spontaneous contractions of human corpora cavernosa (HCC) strips. In addition, MPSi-NP induced maximal relaxation of phenylephrine precontracted HCC by 118.6 ± 3.6%, and in comparison, tadalafil induced a maximal relaxation of HCC by 98.3 ± 1.2%. Similarly, the sGC inhibitor blocked the MPSi-NP relaxation. MPSi-NP potentiated the relaxation induced by tadalafil. MPSi-NP increased cGMP levels in HCC strips by 2.6-fold and increased by 3.5-fold the phosphorylation level of the VASP protein, which is a downstream target to PKG. MPSi-NP effectively relaxes RbCC and HCC by activating the sGC-PKG pathway and potentiates the tadalafil response. MPSi-NP could be helpful in conditions where nitric oxide availability is decreased. A topical gel formulation of MPSi-NP could be used as a rescue therapy to treat true non-responders of PDE5Is drugs.

Effect of Purified Resveratrol Butyrate Ester Monomers against Hypertension after Maternal High-Fructose Intake in Adult Offspring.

Offspring hypertension arising from adverse maternal conditions can be mitigated through dietary nutritional supplementation, including resveratrol. Previously, we identified derivatives of resveratrol butyrate ester (RBE), specifically 3,4'-di-O-butanoylresveratrol (ED2) and 3-O-butanoylresveratrol (ED4), demonstrating their superior antioxidant capabilities compared to RBE itself. This study sought to assess the protective impact of maternal supplementation with ED2 or ED4 on offspring hypertension in a rat model subjected to a high-fructose (HF) diet during pregnancy and lactation. Female Sprague-Dawley rats were distributed into distinct dietary groups throughout pregnancy and lactation: (1) standard chow; (2) HF diet (60%); (3) HF diet supplemented with ED2 (25 mg/L); and (4) HF diet supplemented with ED4 (25 mg/L). Male offspring were euthanized at the age of 12 weeks. The maternal HF diet induced hypertension in the offspring, which was mitigated by perinatal supplementation with either ED2 or ED4. These protective effects were attributed to the antioxidant properties of ED2 and ED4, resulting in an increased availability of nitric oxide (NO). Additionally, supplementation with ED2 was connected to an increased abundance of Bifidobacterium and Clostridium genera, which was accompanied by a decrease in Angelakisella and Christensenella. On the other hand, ED4 supplementation shielded rat offspring from hypertension by elevating concentrations of short-chain fatty acids (SCFAs) and their receptors while reducing trimethylamine-N-oxide (TMAO) levels. These findings highlight the potential of purified RBE monomers, ED2 and ED4, as preventive measures against hypertension resulting from a maternal high-fructose diet. Further research is warranted to explore their clinical applications based on these promising results.

Pharmacological Treatments for Erectile Dysfunction in Diabetic Patients: Efficacy, Safety, and Emerging Therapies

Men with diabetes mellitus, particularly those with type 2 diabetes (T2DM), are known to experience erectile dysfunction (ED), a condition whose prevalence has risen to 75% in recent years. The pathophysiology of ED in diabetic patients involves vascular impairment, neuropathy, hormonal dysregulation, and chronic hyperglycemia, all of which contribute to endothelial dysfunction, reduced nitric oxide availability, and nerve damage. Phosphodiesterase type 5 (PDE5) inhibitors, such as sildenafil, tadalafil, and vardenafil, are the first-line pharmacological treatments for ED, though their efficacy is reduced in diabetic patients due to the extent of vascular and neurological damage. Other treatments, including testosterone replacement therapy (TRT), intracavernosal injections, and vacuum erection devices (VEDs), provide alternatives for patients unresponsive to PDE5 inhibitors. Emerging therapies such as low-intensity extracorporeal shockwave therapy (LI-ESWT) and regenerative medicine approaches, including stem cell and platelet-rich plasma (PRP) injections, show potential in improving erectile function in diabetic patients. Glycemic control plays a critical role in both preventing ED and enhancing the efficacy of treatments by improving vascular function and reversing nerve damage. This review was conducted through an extensive analysis of current literature on pharmacological and emerging treatments for ED in diabetic patients. In conclusion, integrating traditional pharmacotherapy with emerging treatments and emphasizing glycemic control holds promise for optimizing ED management in diabetic patients. Keywords: Erectile Dysfunction (ED), Diabetes Mellitus (T2DM), Phosphodiesterase Type 5 (PDE5) Inhibitors, Testosterone Replacement Therapy (TRT), Glycemic Control

Sex differences in the predictors of skeletal muscle microvascular reactivity in older individuals

Aging is associated with an increased risk of cardiovascular disease and vascular dysfunction. Reduced nitric oxide bioavailability is considered one of the key mechanisms underlying vascular dysfunction in large arteries of older adults. However, the relationship between cardiovascular disease risk factors, nitric oxide bioavailability, and skeletal muscle microvascular reactivity, an early hallmark in cardiovascular disease progression, is unclear in older individuals. Also uncertain is whether this relationship is influenced by sex. Therefore, this study assessed the association between cardiovascular disease risk factors, circulating markers of nitric oxide availability (plasma nitrate and nitrite), and skeletal muscle microvascular reactivity in older individuals. First, we confirmed in a cohort of young and older individuals that aging is associated with skeletal muscle microvascular dysfunction. Next, we observed that skeletal muscle microvascular reactivity (P = 0.653; η2 = 0.016) and circulating nitric oxide metabolites (Nitrate: P = 0.641, η2 = 0.011; Nitrite: P = 0.560, η2 = 0.017; NOx: P = 0.639, η2 = 0.011) did not differ between older males and females. Finally, using multivariate regression models, we found that: (i) the number of cardiovascular risk factors was negatively associated with skeletal muscle microvascular reactivity in older males and females (B = −0.132, P = 0.044); (ii) the relationship between plasma nitrite and skeletal muscle microvascular reactivity was influenced by sex (F = 6.837, P = 0.016); and (iii) skeletal muscle microvascular reactivity in older females displayed a strong positive association with plasma nitrite (R2 = 0.720, P < 0.001). While the impact of cardiovascular disease risk factors on skeletal muscle microvascular reactivity was not influenced by sex, sex-related discrepancies were found in the relationship between nitric oxide bioavailability and skeletal muscle microvascular reactivity in older individuals.

P224 EFFECT OF SODIUM NITRITE ON RENAL DAMAGE FROM 2-KIDNEY, 1-CLIP (2K-1C) HYPERTENSION IN RATS

Renovascular hypertension is characterized by oxidative stress and decreased availability of nitric oxide (NO). Nitrite is a physiologically recycled metabolite that generates NO. Treatment with sodium nitrite has antihypertensive effects due to its antioxidant capacity. However, the renal effects of this treatment are not known in 2K1C hypertension. This study aims to evaluate the effect of treatment with sodium nitrite on kidney damage caused by 2K1C hypertension. Hypertension was induced by cleavage of the left renal artery in Wistar rats. Two weeks after surgery, the animals were treated with two doses (1 mg/kg/day or 15 mg/kg/day) of sodium nitrite or vehicle for 4 weeks, by gavage. Blood pressure (BP) was checked weekly by tail plethysmography. To assess renal function, plasma urea and creatinine were determined. Kidney oxidative stress was evaluated through the activity of catalase (CAT), superoxide dismutase (SOD), levels of reduced glutathione (GSH), lipid peroxidation, and superoxide (O2-) levels. Treatment with 15 mg/kg/day of sodium nitrite reversed the increase in BP in 2K1C rats (p&lt;0.05, 2K1C:170.5±6.542; 2K1C+Nitrite15:162.4±6.712 mmHg), and improved renal function previously impaired by hypertension (urea, p&lt;0.05; 2K1C:76.37±24.53; 2K1C+Nitrite15:47.82±13.86; creatinine, p&lt;0.05; 2K1C:0.540±0.105; 2K1C+Nitrite15:0.3550±0.117). SOD activity decreased in the kidneys of hypertensive animals (p&lt;0.05, Control:0.7176±0.06426; 2K1C:0.636±0.0888; 2K1C+Nitrite1:0.703±0.0866; 2K1C+Nitrite15:0.648±0.173). As for CAT and GSH, there was a decrease in activity in hypertensive animals, with improvement in the group treated with nitrite 15 mg/kg/day (CAT p&lt;0.05, Control:0.651±0.255; 2K1C:0.2772±0.1837; 2K1C+Nitrite15: 0.6654±0.1440 and GSH: p&lt;0.05, Control:44.80±10.59; 2K1C: 29,62±7,253 2K1C+Nitrite15:44.25±10.07). Lipid peroxidation increased by hypertension was reduced with treatment at the highest dosage (p&lt;0.05, Control:0.314±0.158; 2K1C:0.497±0.113; 2K1C+Nitrite15:0.278±0.084). O2- levels were decreased in all groups treated with nitrite (p&lt;0.05, 2K1C:3.844±1.598; 2K1C+Nitrite1:0.9643±0.2063; 2K1C+Nitrite15:0.4431±0.1838). Our results suggest that sodium nitrite treatment improves 2K1C renal damage through its antioxidant activity. Acknowledgments: FAPEMIG# APQ-00946-23, CNPq# 302076/2022-0

Targeting inflammation and incrementing nitric oxide availability to reduce vascular dysfunction in type 2 diabetes

Targeting inflammation and incrementing nitric oxide availability to reduce vascular dysfunction in type 2 diabetes

Endothelial dysfunction: molecular mechanisms and clinical implications.

Cardiovascular disease (CVD) and its complications are a leading cause of death worldwide. Endothelial dysfunctionplays a crucial role in the initiation and progression of CVD, serving as a pivotal factor in the pathogenesis of cardiovascular, metabolic, and other related diseases. The regulation of endothelial dysfunction is influenced by various risk factors and intricate signaling pathways, which vary depending on the specific disease context. Despite numerous research efforts aimed at elucidating the mechanisms underlying endothelial dysfunction, the precise molecular pathways involved remain incompletely understood. This review elucidates recent research findings on the pathophysiological mechanisms involved in endothelial dysfunction, including nitric oxide availability, oxidative stress, and inflammation-mediated pathways. We also discuss the impact of endothelial dysfunction on various pathological conditions, including atherosclerosis, heart failure, diabetes, hypertension, chronic kidney disease, and neurodegenerative diseases. Furthermore, we summarize the traditional and novel potential biomarkers of endothelial dysfunction as well as pharmacological and nonpharmacological therapeutic strategies for endothelial protection and treatment for CVD and related complications. Consequently, this review is to improve understanding of emerging biomarkers and therapeutic approaches aimed at reducing the risk of developing CVD and associated complications, as well as mitigating endothelial dysfunction.

Mechanisms of Flavonoids and Their Derivatives in Endothelial Dysfunction Induced by Oxidative Stress in Diabetes.

Diabetic complications pose a significant threat to life and have a negative impact on quality of life in individuals with diabetes. Among the various factors contributing to the development of these complications, endothelial dysfunction plays a key role. The main mechanism underlying endothelial dysfunction in diabetes is oxidative stress, which adversely affects the production and availability of nitric oxide (NO). Flavonoids, a group of phenolic compounds found in vegetables, fruits, and fungi, exhibit strong antioxidant and anti-inflammatory properties. Several studies have provided evidence to suggest that flavonoids have a protective effect on diabetic complications. This review focuses on the imbalance between reactive oxygen species and the antioxidant system, as well as the changes in endothelial factors in diabetes. Furthermore, we summarize the protective mechanisms of flavonoids and their derivatives on endothelial dysfunction in diabetes by alleviating oxidative stress and modulating other signaling pathways. Although several studies underline the positive influence of flavonoids and their derivatives on endothelial dysfunction induced by oxidative stress in diabetes, numerous aspects still require clarification, such as optimal consumption levels, bioavailability, and side effects. Consequently, further investigations are necessary to enhance our understanding of the therapeutic potential of flavonoids and their derivatives in the treatment of diabetic complications.

Atherogenic Effect of Homocysteine, a Biomarker of Inflammation and Its Treatment.

Hyperhomocysteinemia (HHcy) is an independent risk factor for atherosclerosis. Ischemic stroke and heart disease, coronary heart disease, and cardiovascular disease are events resulting from long-lasting and silent atherosclerosis. This paper deals with the synthesis of homocysteine (Hcy), causes of HHcy, mechanism of HHcy-induced atherosclerosis, and treatment of HHcy. Synthesis and metabolism of Hcy involves demethylation, transmethylation, and transsulfuration, and these processes require vitamin B 6 and vitamin B 12 folic acid (vitamin B 9 ). Causes of HHcy include deficiency of vitamins B 6 , B 9 , and B 12 , genetic defects, use of smokeless tobacco, cigarette smoking, alcohol consumption, diabetes, rheumatoid arthritis, low thyroid hormone, consumption of caffeine, folic acid antagonist, cholesterol-lowering drugs (niacin), folic acid antagonist (phenytoin), prolonged use of proton pump inhibitors, metformin, and hypertension. HHcy-induced atherosclerosis may be mediated through oxidative stress, decreased availability of nitric oxide (NO), increased expression of monocyte chemoattractant protein-1, smooth muscle cell proliferation, increased thrombogenicity, and induction of arterial connective tissue. HHcy increases the generation of atherogenic biomolecules such as nuclear factor-kappa B, proinflammatory cytokines (IL-1β, IL-6, and IL-8), cell adhesion molecules (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selection), growth factors (IGF-1 and TGF-β), and monocyte colony-stimulating factor which lead to the development of atherosclerosis. NO which is protective against the development of atherosclerosis is reduced by HHcy. Therapy with folic acid, vitamin B 6 , and vitamin B 12 lowers the levels of Hcy, with folic acid being the most effective. Dietary sources of folic acid, vitamin B 6 , vitamin B 12 , omega-3 fatty acid, and green coffee extract reduce Hcy. Abstaining from drinking coffee and alcohol, and smoking also reduces blood levels of Hcy. In conclusion, HHcy induces atherosclerosis by generating atherogenic biomolecules, and treatment of atherosclerosis-induced diseases may be by reducing the levels of Hcy.

Resveratrol Propionate Ester Supplement Exerts Antihypertensive Effect in Juvenile Rats Exposed to an Adenine Diet via Gut Microbiota Modulation.

Resveratrol, acting as a prebiotic, and propionate, functioning as a postbiotic, hold promise for preventing hypertension in chronic kidney disease (CKD). Previously, we employed propionate to enhance the bioavailability of resveratrol through esterification, resulting in the production of a resveratrol propionate ester (RPE) mixture. In this study, we purified 3-O-propanoylresveratrol (RPE2) and 3,4'-di-O-propanoylresveratrol (RPE4) and investigated their protective effects in a juvenile rat adenine-induced CKD model. To this end, male Sprague Dawley rats aged three weeks (n = 40) were divided into five groups: control; CKD (rats fed adenine); CKRSV (CKD rats treated with 50 mg/L resveratrol); CDRPE2 (CKD rats treated with 25 mg/L RPE2); and CKRPE4 (CKD rats treated with 25 mg/L RPE 4). RPE2 and PRE4 similarly exhibited blood pressure-lowering effects comparable to those of resveratrol, along with increased nitric oxide (NO) availability. Furthermore, RPE2 and RPE4 positively influenced plasma short-chain fatty acid (SCFA) levels and induced distinct alterations in the gut microbial composition of adenine-fed juvenile rats. The supplementation of RPE2 and RPE4, by restoring NO, elevating SCFAs, and modulating the gut microbiota, holds potential for ameliorating CKD-induced hypertension.

Hypoxia-induced NOS1 as a therapeutic target in hypercholesterolemia-related colorectal cancer

BackgroundIt is well established that hypercholesterolemia increases the risk of atherosclerosis, especially because it reduces the availability of nitric oxide (NO). However, the relationship between hypercholesterolemia and NO in regulating colorectal cancer development and progression remains unknown.MethodsWe conducted bioinformatics analysis, qRT-PCR, ChIP-qPCR assays, luciferase report assays, clonogenic survival assays, and multiple mouse models to investigate the function and mechanism of hypercholesterolemia in regulating NO signaling. Additionally, NOS inhibitors were used to evaluate the potential of therapeutic strategy in anti-tumor response.ResultsHere, we show that oxidized low-density lipoprotein (oxLDL) cholesterol and its receptor LOX-1 are essential for hypercholesterolemia-induced colorectal tumorigenesis. Mechanically, the oxLDL promotes the oxidant stress-dependent induction of hypoxia signaling to transcriptionally up-regulate NO synthase (NOS) especially NOS1 expression in colorectal cancer (CRC) cells. More importantly, our results suggested that selective inhibition of NOS1 with its specific inhibitor Nω-Propyl-L-arginine is a suitable therapeutic strategy for hypercholesterolemia-related CRC with both efficacy and toxicity reduction.ConclusionsOur findings established that hypercholesterolemia induces the oxidant stress-dependent induction of hypoxia signaling to transcriptionally up-regulate NOS1 expression in CRC cells, and the clinically applicable NOS1 inhibitor Nω-Propyl-L-arginine represents an effective therapeutic strategy for hypercholesterolemia-related CRC.

Distinct metabolic responses to heme in inflammatory human and mouse macrophages – Role of nitric oxide

Activation of inflammation is tightly associated with metabolic reprogramming in macrophages. The iron-containing tetrapyrrole heme can induce pro-oxidant and pro-inflammatory effects in murine macrophages, but has been associated with polarization towards an anti-inflammatory phenotype in human macrophages. In the current study, we compared the regulatory responses to heme and the prototypical Toll-like receptor (TLR)4 ligand lipopolysaccharide (LPS) in human and mouse macrophages with a particular focus on alterations of cellular bioenergetics. In human macrophages, bulk RNA-sequencing analysis indicated that heme led to an anti-inflammatory transcriptional profile, whereas LPS induced a classical pro-inflammatory gene response. Co-stimulation of heme with LPS caused opposing regulatory patterns of inflammatory activation and cellular bioenergetics in human and mouse macrophages. Specifically, in LPS-stimulated murine, but not human macrophages, heme led to a marked suppression of oxidative phosphorylation and an up-regulation of glycolysis. The species-specific alterations in cellular bioenergetics and inflammatory responses to heme were critically dependent on the availability of nitric oxide (NO) that is generated in inflammatory mouse, but not human macrophages. Accordingly, studies with an inducible nitric oxide synthase (iNOS) inhibitor in mouse, and a pharmacological NO donor in human macrophages, reveal that NO is responsible for the opposing effects of heme in these cells. Taken together, the current findings indicate that NO is critical for the immunomodulatory role of heme in macrophages.

Exploring the effects of vasoactive constituents in large cardamom: implications for the anti-hypertensive effect via eNOS coupling pathway – an in-vitro study in rat endothelial cells

Endothelial dysfunction, linked to reduced eNOS expression and nitric oxide (NO) availability, contributes to cardiovascular diseases (CVDs). Large cardamom exhibits antihypertensive effects by augmenting NO levels and antioxidant activity. To decipher its mechanisms, selected constituents were docked with eNOS-associated target genes such as GTP cyclohydrolase I (GTPCH-1) and (dihydrofolate reductase [DHFR]). Endothelial damage induced by L-NAME and fructose was countered by assessing nitric oxide metabolites (NOx), tetrahydrobipterin (BH4 levels), GCH-I expression and super oxide dismutase (SOD) activity after constituent incubation. Cyanidin-3-O-glucoside and petunidin-3-O-glucoside notably restored impaired vascular markers in both models. These phytoconstituents are likely to activate GCH-BH4-eNOS pathways, upregulating SOD and NO expression, maintaining endothelial integrity. Large cardamom’s antihypertensive effects may stem from these components, synergistically enhancing endothelial NO release via the eNOS pathway.

Diaphragm Force and Mitochondrial Function Following Enhanced Nitric Oxide Availability During Mechanical Ventilation

During mechanical ventilation (MV), force developed by the diaphragm decreases over time much faster than locomotor muscles, known as ventilator-induced diaphragm dysfunction (VIDD). VIDD is accompanied by an increase in intramyofiber protein S-nitrosylation, a modification of cysteines by nitric oxide (NO). During the treatment of acute respiratory distress syndrome (ARDS), inhaled NO is commonly used to improve gas exchange, but little is known about the effects of increased NO availability to the diaphragm during MV and the intracellular mechanisms to protect against excessive S-nitrosylation. We hypothesize that the enzyme S-nitrosoglutathione reductase (GSNOR) protects against excessive protein S-nitrosylation in diaphragm myofibers in conditions where NO availability is enhanced during MV, thereby preserving contractile function. We tested this hypothesis by enhancing NO availability and blocking GSNOR activity in mice during MV. Mice were treated with GSNOR inhibitor (SPL-334; GSNORi) or both GSNORi and NO donor isosorbide dinitrate (GSNORi-ISDN) together, and mechanically ventilated for 2h. E x vivo diaphragm force and mitochondrial respiration were measured. Male (C57BL/6J) 3-4 month old mice (n=27) were anesthetized and subjected to MV for 0 (non-MV), 2, 4, or 6h (150 breaths/min, 10 cmH2O PIP, 3.5 cmH2O PEEP. 8 mL/kg VT). Alternatively, mice were treated with PBS/10% DMSO (DMSO, n=6) or 25 μg SPL-334 in PBS/DMSO (GSNORi, n=6) or 25 μg SPL-334 + 1.7 mg ISDN in PBS/DMSO (GSNORi-ISDN; n=6), and then subjected to MV for 2 h. After MV, mice were euthanized, and diaphragm strips were used for force, and permeabilized fiber bundles for mitochondrial oxidative phosphorylation and H2O2 generation measurements. Peak tetanic force was decreased by MV ~23% at 4 h and ~40% at 6 h (P=0.0183 and P=0.0062, respectively, one-way ANOVA, Tukey post-test) vs 0 h. However, peak force was not different between DMSO, GSNORi and GSNORi-ISDN at 2 h MV. Coupled-phosphorylating mitochondrial respiration (Kruskal-Wallis H=2.2, p=0.35) was not different but H2O2 flux was highest in GSNORi-ISDN vs DMSO and GSNORi (Kruskal-Wallis H=6.6, p=0.03). GSNORi and ISDN treatment during MV did not produce any changes to VIDD and to mitochondrial respiration, but increased ROS production. If exogenous NO is not provided, inhibiting GSNOR in vivo alone does not affect diaphragm function ex vivo during short MV. Support: TRDRP (T32IR5221 and T29KT0397CA, to L.N.) and SDSU 2023 SEED Grant (to L.N.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Pulmonary Hypertension in Sickle Cell Disease: Novel Findings of Gene Polymorphisms Related to Pathophysiology.

Pulmonary hypertension (PH) is a progressive and potentially fatal complication of sickle cell disease (SCD), affecting 6-10% of adult SCD patients. Various mechanisms and theories have been evaluated to explain the pathophysiology of this disease. However, questions remain, particularly regarding the clinical heterogeneity of the disease in terms of symptoms, complications, and survival. Beyond the classical mechanisms that have been thoroughly investigated and include hemolysis, nitric oxide availability, endothelial disorders, thrombosis, and left heart failure, attention is currently focused on the potential role of genes involved in such processes. Potential candidate genes are investigated through next-generation sequencing, with the transforming growth factor-beta (TGF-β) pathway being the initial target. This field of research may also provide novel targets for pharmacologic agents in the future, as is already the case with idiopathic PH. The collection and processing of data and samples from multiple centers can yield reliable results that will allow a better understanding of SCD-related PH as a part of the disease's clinical spectrum. This review attempts to capture the most recent findings of studies on gene polymorphisms that have been associated with PH in SCD patients.

Homocysteine modifies the association of coronary stenosis and HIV infection in an inner city African American population.

People with HIV (PWH) whose disease is controlled on anti-retroviral regimens remain at an increased risk for coronary artery disease (CAD). Traditional cardiovascular risk factors do not fully explain the residual risk in PWH suggesting contributions from nontraditional factors. Homocysteine (Hcy) may be one of these as prior work in adults without HIV demonstrate that Hcy may impair endothelial function by decreasing the availability of nitric oxide, promoting the development of atherosclerosis. In addition, plasma Hcy levels are higher in PWH than in individuals living without HIV. The aim of this study was to investigate whether Hcy levels influence the association between HIV and coronary stenosis in an inner city African American population. African Americans from the Heart Study in Baltimore, with and without HIV, recruited from inner-city Baltimore between June 2004 and February 2015, were included in this analysis. Participants underwent coronary CT angiography to evaluate the presence of coronary stenosis, defined as luminal stenosis >10%. Hcy was measured from stored serum samples. In this analysis, the median [IQR] age of the 664 participants was 56 [50-66] years; 68.1% were living with HIV and 43.1% were women. Elevated Hcy (>15µmol/L) was more prevalent in those with coronary stenosis (23.3%, 95% CI: 18.4%-28.2%) than in those without coronary stenosis (13.1%, 95% CI: 9.7%-16.5%) (p = 0.0007), and HIV was associated with coronary stenosis in those participants with an elevated Hcy (Prevalence Ratio: 1.94, 95% CI: 1.04-3.64, p = 0.0038) and not in those with a Hcy ≤15µmol/L (Prevalence Ratio: 1.02, 95% CI: 0.83-1.25, p = 0.87). Our data suggest an association between elevated Hcy levels (>15µmol/L) and the prevalence of coronary stenosis in PWH from this inner city African American population.

Arginine Supplementation in MELAS Syndrome: What Do We Know about the Mechanisms?

MELAS syndrome, characterized by mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes, represents a devastating mitochondrial disease, with the stroke-like episodes being its primary manifestation. Arginine supplementation has been used and recommended as a treatment for these acute attacks; however, insufficient evidence exists to support this treatment for MELAS. The mechanisms underlying the effect of arginine on MELAS pathophysiology remain unclear, although it is hypothesized that arginine could increase nitric oxide availability and, consequently, enhance blood supply to the brain. A more comprehensive understanding of these mechanisms is necessary to improve treatment strategies, such as dose and regimen adjustments; identify which patients could benefit the most; and establish potential markers for follow-up. This review aims to analyze the existing evidence concerning the mechanisms through which arginine supplementation impacts MELAS pathophysiology and provide the current scenario and perspectives for future investigations.