The cardioprotective effect of ischemic preconditioning (IPC) and ischemic postconditioning (IPoC) in adult hearts is mediated by nitric oxide (NO). During the early developmental period, rat hearts exhibit higher resistance to ischemia-reperfusion (I/R) injury, contain higher levels of serum nitrates, and their resistance cannot be further increased by IPC or IPoC. NOS blocker (L-NAME) lowers their high resistance. Wistar rat hearts (postnatal Days 1 and 10) were perfused according to Langendorff and exposed to 40 min of global ischemia followed by reperfusion with or without IPoC. NO and reactive oxygen species donors (DEA-NONO, SIN-1) and L-NAME were administered. Tolerance to ischemia decreased between Days 1 and 10. DEA-NONO (low concentrations) significantly increased tolerance to I/R injury on both Days 1 and 10. SIN-1 increased tolerance to I/R injury on Day 10, but not on Day 1. L-NAME significantly reduced resistance to I/R injury on Day 1, but actually increased resistance to I/R injury on Day 10. Cardioprotection by IPoC on Day 10 was not affected by either NO donors or L-NAME. It can be concluded that resistance of the neonatal heart to I/R injury is NO dependent, but unlike in adult hearts, cardioprotective interventions, such as IPoC, are most likely NO independent.

Recently, we compared an interplay of the adenosine system and nitric oxide (NO) in the regulation of renal function between male normoglycaemic (NG) and streptozotocin-induced diabetic rats (DM). Considering the between-sex functional differences, e.g., in the NO status, we present similar studies performed in female rats. We examined if the theophylline effects (non-selective adenosine antagonist) in NG and DM females with or without active NO synthases differed from the earlier findings. In anaesthetised female Sprague Dawley rats, both NG and DM, untreated or after NO synthesis blockade with L-NAME, theophylline effects, on blood pressure, renal hemodynamics and excretion, and renal tissue NO were investigated. Renal artery blood flow (Transonic probe), cortical, outer-, and inner-medullary flows (laser-Doppler technique), and renal tissue NO signal (selective electrode) were measured. In contrast to males, in female NG and DM rats, theophylline induced renal vasodilation. In NO-deficient females, theophylline induced comparable renal vasodilatation, confirming the vasoconstrictor influence of the renal adenosine. In NG and DM females with intact NO synthesis, adenosine inhibition diminished kidney tissue NO, contrasting with an increase reported in males. Lowered baseline renal excretion in DM females suggested stimulation of renal tubular reabsorption due to the prevalence of antinatriuretic over natriuretic tubular action of adenosine receptors. An opposite inter-receptor balance pattern emerged previously from male studies. The study exposed between-sex functional differences in the interrelation of adenosine and NO in rats with normoglycaemia and streptozotocin diabetes. The findings also suggest that in diabetes mellitus, the abundance of individual receptor types can distinctly differ between females and males.

To reveal the interaction of oxidative stress and protein S-nitrosylation on mitochondrial pathway apoptosis and tenderness development in postmortem yak meat. Herein, we selected yak longissimus dorsi muscle as the research object and treated hydrogen peroxide (H2O2) with S-nitrosoglutathione agent (GSNO) as well as Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) in mixed injections with 0.9 % saline as a control group, followed by incubation at 4 °C for 12, 24, 72, 120 and 168 h. Results showed that this interaction significantly increased mitochondrial ROS and NO content (P < 0.05) while weakening the antioxidant capacity of GSH and TRX redox response systems or accelerating the Ca2+ release process, leading to mitochondrial functional impairment and increased apoptosis rate. Notably, the H2O2 + L-NAME group showed more pronounced apoptosis. Hence, we suggest that the interaction between oxidative stress and protein S-nitrosylation could positively regulate yak meat tenderization.

This study aimed to investigate the effects of the n-hexane fraction of the ethanolic seed extract of PG (NFESEPG) on hypertension induced by Nω-nitro-L-arginine methyl ester (L-NAME) in rats. Specifically, the study examined the impact of NFESEPG on blood pressure, oxidative stress markers, NO concentration, angiotensin-converting enzyme (ACE) and arginase activities, and cardiac biomarkers in hypertensive rats. The study involved collecting, identifying, and processing the PG plant to obtain the ethanolic seed extract. The extract was then partitioned with solvents to isolate the n-hexane fraction. Hypertension was induced in rats by oral administration of L-NAME for 10 days, while concurrent treatment with NFESEPG at two doses (200 and 400 mg/kg/day) was administered orally. Blood pressure was measured using a noninvasive tail-cuff method, and various biochemical parameters were assessed. Treatment with both doses of NFESEPG significantly reduced systolic and diastolic blood pressure in L-NAME-induced hypertensive rats. Additionally, NFESEPG administration increased NO concentration and decreased ACE and arginase activities, malondialdehyde (MDA) levels, and cardiac biomarkers in hypertensive rats. The findings indicate that NFESEPG effectively lowered blood pressure in hypertensive rats induced by L-NAME, potentially through mechanisms involving the modulation of oxidative stress, NO bioavailability, and cardiac biomarkers. These results suggest the therapeutic potential of NFESEPG in managing hypertension and related cardiovascular complications.

Lipid emulsions are used as adjuvant drugs to alleviate intractable cardiovascular collapse induced by drug toxicity. We aimed to examine the effect of lipid emulsions on labetalol-induced vasodilation and the underlying mechanism in the isolated rat aorta. We studied the effects of endothelial denudation, NW-nitro-l-arginine methyl ester (l-NAME), calmidazolium, methylene blue, 1H-[1,2,4]oxadiazolo[4,3-a] quinoxalin-1-one (ODQ), and lipid emulsions on labetalol-induced vasodilation. We also evaluated the effects of lipid emulsions on cyclic guanosine monophosphate (cGMP) formation, endothelial nitric oxide synthase (eNOS) phosphorylation, and endothelial calcium levels induced by labetalol. Labetalol-induced vasodilation was higher in endothelium-intact aortas than that in endothelium-denuded aortas. l-NAME, calmidazolium, methylene blue, and ODQ inhibited labetalol-induced vasodilation in endothelium-intact aortas. Lipid emulsions inhibited labetalol-induced vasodilation in endothelium-intact and endothelium-denuded aortas. l-NAME, ODQ, and lipid emulsions inhibited labetalol-induced cGMP formation in endothelium-intact aortas. Lipid emulsions reversed the stimulatory and inhibitory eNOS (Ser1177 and Thr495) phosphorylation induced by labetalol in human umbilical vein endothelial cells and inhibited the labetalol-induced endothelial calcium increase. Moreover, it decreased labetalol concentration. These results suggest that lipid emulsions inhibit vasodilation induced by toxic doses of labetalol, which is mediated by the inhibition of endothelial nitric oxide release and reduction of labetalol concentration.

We reported that salt-sensitive hypertension (SSHTN) is associated with increased pro-inflammatory immune cells, inflammation, and inflammation-associated lymphangiogenesis in the kidneys and gonads of male and female mice. However, it is unknown whether these adverse end organ effects result from increased blood pressure (BP), elevated levels of salt, or both. We hypothesized that pharmaceutically lowering BP would not fully alleviate the renal and gonadal immune cell accumulation, inflammation, and lymphangiogenesis associated with SSHTN. SSHTN was induced in male and female C57BL6/J mice by administering nitro-L-arginine methyl ester hydrochloride (L-NAME; 0.5 mg/ml) in their drinking water for 2 weeks, followed by a 2-week washout period. Subsequently, the mice received a 3-week 4% high salt diet (SSHTN). The treatment group underwent the same SSHTN induction protocol but received hydralazine (HYD; 250 mg/L) in their drinking water during the diet phase (SSHTN+HYD). Control mice received tap water and a standard diet for 7 weeks. In addition to decreasing systolic BP, HYD treatment generally decreased pro-inflammatory immune cells and inflammation in the kidneys and gonads of SSHTN mice. Furthermore, the decrease in BP partially alleviated elevated renal and gonadal lymphatics and improved renal and gonadal function in mice with SSHTN. These data demonstrate that high systemic pressure and salt differentially act on end organ immune cells, contributing to the broader understanding of how BP and salt intake collectively shape immune responses and highlight implications for targeted therapeutic interventions.

BACKGROUND: It has been previously demonstrated that the maintenance of ischemic acidic pH or the delay of intracellular pH recovery at the onset of reperfusion decreases ischemic-induced cardiomyocyte death.
OBJECTIVE: To examine the role played by nitric oxide synthase (NOS)/NO-dependent pathways in the effects of acidic reperfusion in a regional ischemia model.
METHODS: Isolated rat hearts perfused by Langendorff technique were submitted to 40 min of left coronary artery occlusion followed by 60 min of reperfusion (IC). A group of hearts received an acid solution (pH = 6.4) during the first 2 min of reperfusion (AR) in absence or in presence of l-NAME (NOS inhibitor). Infarct size (IS) and myocardial function were determined. In cardiac homogenates, the expression of P-Akt, P-endothelial and inducible isoforms of NOS (P-eNOS and iNOS) and the level of 3-nitrotyrosine were measured. In isolated cardiomyocytes, the intracellular NO production was assessed by confocal microscopy, under control and acidic conditions. Mitochondrial swelling after Ca2+ addition and mitochondrial membrane potential (Δψ) were also determined under control and acidosis.
RESULTS: AR decreased IS, improved postischemic myocardial function recovery, increased P-Akt and P-eNOS, and decreased iNOS and 3-nitrotyrosine. NO production increased while mitochondrial swelling and Δψ decreased in acidic conditions. l-NAME prevented the beneficial effects of AR.
CONCLUSIONS: Our data strongly supports that a brief acidic reperfusion protects the myocardium against the ischemia-reperfusion injury through eNOS/NO-dependent pathways.

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) is a common syndrome with high morbidity and mortality but without available evidence-based therapies. It is essential to investigate changes in gene expression profiles in preclinical HFpEF animal models, with the aim of searching for novel therapeutic targets.
METHODS: Wild-type male C57BL/6J mice were administrated with a combination of high-fat diet (HFD) and inhibition of constitutive nitric oxide synthase using N-nitro-l-arginine methyl ester (l-NAME) for 5 and 7 weeks. RNA sequencing was conducted to detect gene expression profiles, and bioinformatic analysis was performed to identify the core genes, pathways, and biological processes involved.
RESULTS: A total of 1,347 genes were differentially expressed in the heart at week 5 and 7 post-intervention. Gene Ontology enrichment analysis indicated that these greatly changed genes were involved mainly in cell adhesion, neutrophil chemotaxis, cell communication, and other functions. Using hierarchical cluster analysis, these differentially expressed genes were classified into 16 profiles. Of these, three significant profiles were ultimately identified. Gene co-expression network analysis suggested troponin T type 1 (Tnnt1) directly regulated 31 neighboring genes and was considered to be at the core of the associated gene network.
CONCLUSIONS: The combined application of RNA sequencing, hierarchical cluster analysis, and gene network analysis identified Tnnt1 as the most important gene in the development of HFpEF.

The transcriptional regulator nuclear factor-κB (NF-κB) is a mediator of endothelial dysfunction. Inhibiting NF-κB with salsalate is used to investigate inflammatory mechanisms contributing to accelerated cardiovascular disease risk. However, in the absence of disease, inhibition of NF-κB can impact redox mechanisms, resulting in paradoxically decreased endothelial function. This study aimed to measure microvascular endothelial function during inhibition of the transcriptional regulator NF-κB in reproductive-aged healthy women. In a randomized, single-blind, crossover, placebo-controlled design, nine healthy women were randomly assigned oral salsalate (1,500 mg, twice daily) or placebo treatments for 5 days. Subjects underwent graded perfusion with the endothelium-dependent agonist acetylcholine (ACh, 10-10 to 10-1 M, 33°C) alone and in combination with 15 mM NG-nitro-l-arginine methyl ester [l-NAME; nonselective nitric oxide (NO) synthase inhibitor] through intradermal microdialysis. Laser-Doppler flux was measured over each microdialysis site, and cutaneous vascular conductance (CVC) was calculated as flux divided by mean arterial pressure and normalized to site-specific maximum (CVC%max; 28 mM sodium nitroprusside + 43°C). The l-NAME sensitive component was calculated as the difference between the areas under the dose-response curves. During the placebo and salsalate treatments, the l-NAME sites were reduced compared with the control sites (both P < 0.0001). Across treatments, there was a significant difference between the control and l-NAME sites, where both sites shifted upward following salsalate treatment (both P < 0.0001), whereas the l-NAME-sensitive component was not different (P = 0.94). These data demonstrate that inhibition of the transcriptional regulator NF-κB improves cutaneous microvascular function in reproductive-aged healthy women through non-NO-dependent mechanisms.NEW & NOTEWORTHY The transcription factor nuclear factor-κB (NF-κB) regulates multiple aspects of innate and adaptive immunity by encoding for genes that participate in inflammation and impact endothelial function following NF-κB inhibition with salsalate treatment. Our results show that cutaneous microvascular function is increased through non-nitric oxide (NO)-dependent mechanisms following salsalate treatment in reproductive-aged healthy women.

Nitric oxide (NO) is a gaseous molecule that regulates various reproductive functions. It is a well-recognized regulator of GnRH-FSH/LH-sex steroid secretion in vertebrates including fish. Kisspeptin is a recently discovered neuropeptide which also regulates GnRH secretion. Nitrergic and kisspeptin neurons are reported in close physical contact in the mammalian brain suggesting their interactive role in the release of GnRH. The existence of kisspeptin and NOS is also demonstrated in vertebrate gonads, but information on their reciprocal relation in gonads, if any, is obscure. Therefore, attempts were made to evaluate the functional reciprocal relation between nitric oxide and kisspeptin in the catfish gonads, if any, by administering the nitric oxide synthase (NOS) inhibitor, L-NAME {N(G)-nitro-L-arginine methyl ester}, which reduces NO production, and kisspeptin agonist (KP-10) and assessing their impacts on the expressions of kisspeptin1, different NOS isoforms, NO and steroid production in the gonadal tissue. The results revealed that L-NAME suppressed the expression of kiss1 in gonads of the catfish establishing the role of NO in kisspeptin expression. However, KP-10 increased the expression of all the isoforms of NOSs (iNOS, eNOS, nNOS) and concurrently NO and steroids in the ovary and testis. In vitro studies also indicate that kisspeptin stimulates the production of NO and estradiol and testosterone levels in the gonadal explants and medium. Thus, in vivo results clearly suggest a reciprocal interaction between kisspeptin and NO to regulate the gonadal activity of the catfish. The in vitro findings further substantiate our contention regarding the interactive role of kisspeptin and NO in gonadal steroidogenesis.