Mesenteric Arterial Bed Research Articles

Melatonin prevents overproduction of reactive oxygen species and vascular dysfunction induced by cyclophosphamide

AimsOverproduction of reactive oxygen species (ROS) is a pathologic hallmark of cyclophosphamide toxicity. For this reason, antioxidant compounds emerge as promising tools for preventing tissue damage induced by cyclophosphamide. We hypothesized that melatonin would display cytoprotective action in the vasculature by preventing cyclophosphamide-induced oxidative stress. Materials and methodsMale C57BL/6 mice (22–25 g) were injected with a single dose of cyclophosphamide (300 mg/kg; i.p.). Mice were pretreated or not with melatonin (10 mg/kg/day, i.p.), given during 4 days before cyclophosphamide injection. Functional (vascular reactivity) and oxidative/inflammatory patterns were evaluated at 24 h in resistance arteries. The antioxidant action of melatonin was assessed in vitro in cultured vascular smooth muscle cells (VSMCs) of mesenteric arteries. Key findingsCyclophosphamide induced ROS generation in both mesenteric arterial bed (MAB) and cultured VSMCs, and this was normalized by melatonin. Cyclophosphamide-induced ROS generation and lipoperoxidation in the bladder and kidney was also prevented by melatonin. Increased levels of tumor necrosis factor (TNF)-α and interleukin (IL)-6 were detected in the MAB of cyclophosphamide-treated mice, all of which were prevented by melatonin. Functional assays using second-order mesenteric arteries of cyclophosphamide-treated mice revealed a decrease in vascular contractility. Melatonin prevented vascular hypocontractility in the cyclophosphamide group. Melatonin partially prevented the decrease in myeloperoxidase (MPO) and N-acetyl-beta-D-glucosaminidase (NAG) activities in the MAB of the cyclophosphamide group. SignificanceMelatonin may constitute a novel and promising therapeutic approach for management of the toxic effects induced by cyclophosphamide in the vasculature.

The Hypotensive and Vasodilatory Effects Observed in Rats Exposed to Chiranthodendron pentadactylon Larreat Flowers Can Be Attributed to Cyanidin 3-O-Glucoside

Chiranthodendron pentadactylon Larreat is a tree native to southeastern Mexico and Guatemala. Its flower is used in Mexican folk medicine to treat a variety of diseases, including conditions of blood pressure. However, scientific information on its usefulness in this pathology is lacking. The present study evaluates the effect of a methanolic extract (ME) from the flower and its active constituents on heart rate (HR) and mean arterial pressure (MAP) in anesthetized rats (MAPHR). The study also analyzed the effects on rat-isolated aortic rings (RIAR) and the rat mesenteric arterial bed (MABR). Active fractions were chromatographed, which led to the isolation of cyanidin 3-O-glucoside (C3G) identified through HPLC. The Chiranthodendron pentadactylon flowers produced hypotensive and vasorelaxant effects associated with C3G. The vasorelaxant effect is a mechanism underlying the synthesis and release of nitric oxide (NO). Neither cholinergic receptors nor prostaglandins are involved. ME and C3G cause cardiovascular depression in anesthetized rats via cholinergic and prostanoid mechanisms. Our research expands the scientific understanding of the flowers on the rat cardiovascular system. This amplifies the appreciation of the flower’s ethnomedicine employed to control blood pressure. However, researchers need to conduct toxicity studies to determine the safety of this plant.

Ethanol consumption favors pro-contractile phenotype of perivascular adipose tissue: A role for interleukin-6

Perivascular adipose tissue (PVAT) exerts anticontractile effect, but under non-physiological conditions it may contribute to vascular dysfunction by releasing pro-inflammatory cytokines. Since PVAT is an important source of interleukin (IL)-6, we evaluated whether this cytokine would contribute to ethanol-induced vascular dysfunction. With this purpose, male C57BL/6 wild-type (WT) or IL-6-deficient mice (IL-6−/−) were treated with ethanol for 12 weeks. Increased blood pressure was evidenced after 4 and 6 weeks of treatment with ethanol in WT and IL-6−/− mice, respectively. In WT mice, ethanol increased plasma and PVAT levels of IL-6. Ethanol favoured pro-contractile phenotype of PVAT in mesenteric arteries from WT, but not IL-6-deficient mice. Functional studies showed that tiron [(a scavenger of superoxide (O2−)] reversed the pro-contractile effect of PVAT in mesenteric arteries from ethanol-treated mice. Ethanol increased the levels of O2− in PVAT from WT mice. Ethanol-induced increase in O2− generation was higher in arteries with PVAT from WT mice when compared to IL-6-deficient mice. Treatment with ethanol augmented myeloperoxidase activity in the mesenteric arterial bed (MAB; with or without PVAT) from WT, but not IL-6-deficient mice. In conclusion, IL-6 contributes to the pro-contractile effect of PVAT by a mechanism that involves increase in ROS generation. Additionally, IL-6 mediates intravascular recruitment of neutrophils in response to ethanol and plays a role in the early stages of ethanol-induced hypertension. Collectively, our findings provide novel evidence for a role of IL-6 in the vascular dysfunction induced by ethanol.

Vasorelaxant Effect of Moroccan Cannabis sativa Threshing Residues on Rat Mesenteric Arterial Bed is Endothelium and Muscarinic Receptors Dependent.

Ethanolic fraction of Moroccan Cannabis sativa threshing residues (EFCS) was evaluated for its vasorelaxant activity. The current work aims to identify the active metabolites in the ethanolic fraction of the EFCS and illustrate their mechanism of action. Free radical scavenging capacity of EFCS was assessed using DPPH method. The EFCS vasodilation activities in phenylephrine-precontracted isolated rat mesenteric arterial beds were investigated in presence of L-NAME (nitric oxide synthase inhibitor), indomethacin (cyclooxygenase inhibitor), potassium channel blockers (namely tetraetylamonium, barium chloride, and glibenclamide), and atropine. Nitric oxide vascular release was measured by electron paramagnetic resonance (EPR) using a spin trap in rat aortic rings. EFCS induced dose-dependent vasorelaxation on mesenteric vascular bed. Incubation of the preparations with L-NAME, ODQ (a soluble guanylyl cyclase inhibitor), or potassium channel blockers reduced the fall of perfusion pressure caused by EFCS. Endothelial denudation or atropine abolished the EFCS's vasorelaxant effect, suggesting involvement of muscarinic receptors and endothelium-relaxing factors. The extract induced nitric oxide release in aortic rings in a similar manner as acetylcholine suggesting an effect of EFCS on the muscarinic receptor and the conductance arteries. Chemical investigation of EFCS identified potential active components namely apigenin and derivatives of luteolin skeleton and also additional components such as neophytadiene, squalene, and β-sitosterol. In conclusion, the vasorelaxant effect of EFCS on rat mesenteric arterial bed, which is dependent of muscarinic receptor activation, nitric oxide, and EDHF, can account for potential therapeutic use against high blood pressure related cardiovascular diseases.

Интенсивность мезентериального кровотока и степень зрелости кишечника у новорожденных группы риска по развитию некротизирующего энтероколита

Актуальность. В последние годы распространяется использование ультразвукового исследования брюшной полости для диагностики некротизирующего энтероколита (НЭК) у новорожденных. На начальных стадиях заболевания толщина стенки кишки, эхогенность и перфузия увеличиваются вследствие воспаления кишечника и отека слизистой оболочки. При прогрессировании НЭК утончение стенки кишечника, отсутствие перфузии и перистальтики превалируют и предупреждают о возможности перфорации кишечника. Это является доказательством диагностического преимущества УЗИ в отношении оценки прогрессирования НЭК. В статье представлены некоторые результаты собственного опыта использования УЗИ брюшной полости для диагностики НЭК у преждевременно рожденных детей. Цель: оценить степень зрелости кишечника и связь между допплеровскими индексами кишечной перфузии и сосудистым сопротивлением в бассейне верхней брыжеечной артерии у недоношенных новорожденных на 1–5-е сутки жизни с риском развития НЭК. Материалы и методы. В статье проведено обследование случайно выбранных 34 недоношенных детей с малой и очень малой массой тела и со сроком гестации 28–36 недель от матерей с отягощенным течением беременности. Оценивались: максимальная систолическая скорость, конечная диастолическая скорость и средняя скорость кровотока при ≥ 5 последовательных циклах сердечных сокращений. На основании этих показателей был рассчитан пульсовой индекс. Результаты. После проведенного исследования на 1–5-е сутки жизни ретроспективно новорожденные были распределены по группам в зависимости от клинических диагнозов в конце раннего неонатального периода. Новорожденные группы риска, родившиеся в асфиксии тяжелой степени, с высокими показателями сосудистого сопротивления в верхней брыжеечной артерии на 1–5-е сутки жизни, а также при толщине стенки кишки менее 1,6 мм имеют повышенный риск развития НЭК. Выводы. Выявленные высокие показатели сосудистого сопротивления в верхней брыжеечной артерии на 1–5-е сутки жизни у недоношенных детей с очень низкой массой тела и высоким риском развития НЭК помогут принимать правильные клинические решения по тактике ведения и лечения, в том числе о начале энтерального питания и расширении его объема.

Anthocyanins Activate Membrane Estrogen Receptors With Nanomolar Potencies to Elicit a Nongenomic Vascular Response Via NO Production.

BackgroundThe vascular pharmacodynamics of anthocyanins is only partially understood. To examine whether the anthocyanin‐induced vasorelaxation is related to membrane estrogen receptor activity, the role of ERα or GPER antagonism was ascertained on anthocyanins or 17‐β estradiol‐(E2) induced vasodilatations and NO production.Methods and ResultsThe rat arterial mesenteric bed was perfused with either anthocyanins or corresponding 3‐O‐glycosides, or E2, to examine rapid concentration‐dependent vasorelaxations. The luminally accessible fraction of NO in mesenteric perfusates before and after anthocyanins or E2 administration was quantified. Likewise, NO‐DAF signal detected NO production in primary endothelial cells cultures incubated with anthocyanins or E2 in the absence and presence of ERα (ICI 182,780) or GPER (G‐36) selective antagonists. Anthocyanins or corresponding glycosides elicited, within minutes, vasodilation with nanomolar potencies; half maximal anthocyanin response reached 50% to 60% efficacy, in contrast to acetylcholine. The vasorelaxation is of rapid onset and exclusively endothelium‐dependent; NOS inhibition annulled the vasorelaxation. The delphinidin vascular response was not modified by 100 nmol/L atropine but significantly attenuated by joint application of ICI plus G‐36 (52±4.6 versus 8.5±1.5%), revealing the role of membrane estrogen receptors. Moreover, the anthocyanin or E2‐induced NO production was antagonized up to 70% by these antagonists. NO‐DAF signal elicited by anthocyanins was annulled by NOS inhibition or by ICI plus G‐36 addition.ConclusionsThe biomedical effect of anthocyanins or 3‐O‐glycosylates derivatives contained in naturally purple‐colored foods or berries is due to increased NO production, and not to the phytochemical's antioxidant potential, highlighting the nutraceutical role of natural products in cardiovascular diseases.

ATP Released in Response to Angiotensin II Contributes to Vasoconstriction in the Rat Mesenteric Arterial Bed in a Sex‐dependent Manner

While vascular tone is affected by multiple mediators released from various component tissues, it has been a long-held belief that the mechanical act of vascular smooth muscle contraction induces ATP release regardless of the stimulus that initiated vasoconstriction. Contrary to this theory, here we present evidence that the release of ATP by vascular smooth muscle is both agonist- and sex-dependent. By utilizing a near-real time luminometric technique developed by our lab, we found that while methoxamine, 5-hydroxytryptamine, and angiotensin II all induced vasoconstriction in the rat mesenteric arterial bed, only angiotensin II caused ATP release. Furthermore, this response was only seen in preparations from male rats, whereas those from female rats showed no ATP release in response to any of the three vasoactive agents tested, indicating a sex difference in this process. When we further investigated the ATP release and perfusion pressure responses to angiotensin II, we found that both were inhibited by losartan, indicating the involvement of AT1 receptors. The nonselective P2 antagonist suramin blocked a significant portion of angiotensin II-stimulated vasoconstriction, suggesting that the action of ATP on P2 receptors may play a critical role in the ability of angiotensin II to cause vasoconstriction. A similar response was seen when angiotensin II was perfused along with NF449, a selective inhibitor of the P2X1 receptor. Angiotensin II-induced ATP release was inhibited by carbenoxolone, a nonspecific gap junction blocker which is known to inhibit pannexin-1 channels, suggesting that this may be the conduit through which this release occurs. Taken together, our findings suggest that activation of vascular AT1 receptors by angiotensin II directly constricts smooth muscle while simultaneously opening carbenoxolone-sensitive channels allowing ATP to be released. This ATP then activates vascular P2X1 receptors, augmenting the AT1-induced vasoconstriction. This process occurs in the mesenteric arterial bed taken from male, but not female, rats.

Hepato- and cardioprotective effects of Baccharis trimera (Less.) DC. against multiple risk factors for chronic noncommunicable diseases.

Cardiovascular diseases are associated with high morbidity and mortality worldwide and have several risk factors, including dyslipidemia, smoking, and hypertension. Studies have evaluated isolated risk factors in experimental models of cardiovascular disease, but few preclinical studies have assessed associations between multiple risk factors. In the present study, hypertensive Wistar rats (Goldblatt 2K1C model) received a 0.5% cholesterol diet and were exposed to tobacco smoke for 8 weeks. During the last 4 weeks, the animals were treated with vehicle, an ethanol-soluble fraction of B. trimera (30, 100, and 300 mg/kg), or simvastatin + enalapril. A group of normotensive, non-dyslipidemic, and non-smoking rats was treated with vehicle. The levels of aspartate aminotransferase, alanine aminotransferase, urea, creatinine, and hepatic and fecal lipids, blood pressure, and mesenteric arterial bed reactivity were evaluated. Cardiac, hepatic, and renal histopathology and tecidual redox state were also investigated. Untreated animals exhibited significant changes in blood pressure, lipid profile, and biomarkers of heart, liver, and kidney damage. Treatment with B. trimera reversed these changes, with effects that were similar to simvastatin + enalapril. These findings suggest that B. trimera may be promising for the treatment of cardiovascular and hepatic disorders, especially disorders that are associated with multiple risk factors.

Novel Pannexin-1-Coupled Signaling Cascade Involved in the Control of Endothelial Cell Function and NO-Dependent Relaxation.

Deletion of pannexin-1 (Panx-1) leads not only to a reduction in endothelium-derived hyperpolarization but also to an increase in NO-mediated vasodilation. Therefore, we evaluated the participation of Panx-1-formed channels in the control of membrane potential and [Ca2+]i of endothelial cells. Changes in NO-mediated vasodilation, membrane potential, superoxide anion (O2·–) formation, and endothelial cell [Ca2+]i were analyzed in rat isolated mesenteric arterial beds and primary cultures of mesenteric endothelial cells. Inhibition of Panx-1 channels with probenecid (1 mM) or the Panx-1 blocking peptide 10Panx (60 μM) evoked an increase in the ACh (100 nM)-induced vasodilation of KCl-contracted mesenteries and in the phosphorylation level of endothelial NO synthase (eNOS) at serine 1177 (P-eNOSS1177) and Akt at serine 473 (P-AktS473). In addition, probenecid or 10Panx application activated a rapid, tetrodotoxin (TTX, 300 nM)-sensitive, membrane potential depolarization and [Ca2+]i increase in endothelial cells. Interestingly, the endothelial cell depolarization was converted into a transient spike after removing Ca2+ ions from the buffer solution and in the presence of 100 μM mibefradil or 10 μM Ni2+. As expected, Ni2+ also abolished the increment in [Ca2+]i. Expression of Nav1.2, Nav1.6, and Cav3.2 isoforms of voltage-dependent Na+ and Ca2+ channels was confirmed by immunocytochemistry. Furthermore, the Panx-1 channel blockade was associated with an increase in O2·– production. Treatment with 10 μM TEMPOL or 100 μM apocynin prevented the increase in O2·– formation, ACh-induced vasodilation, P-eNOSS1177, and P-AktS473 observed in response to Panx-1 inhibition. These findings indicate that the Panx-1 channel blockade triggers a novel complex signaling pathway initiated by the sequential activation of TTX-sensitive Nav channels and Cav3.2 channels, leading to an increase in NO-mediated vasodilation through a NADPH oxidase-dependent P-eNOSS1177, which suggests that Panx-1 may be involved in the endothelium-dependent control of arterial blood pressure.

Hydrogen sulfide as a mediator of endothelium-dependent relaxation evoked by Moringa oleifera leaf extract in mesenteric arterial beds isolated from L-NAME hypertensive rats.

Aqueous extract of Moringa oleifera leaves (MOE) is a potent inducer of endothelium-dependent relaxation of mesenteric resistance arteries of rats induced to be hypertensive using Nω-nitro-L-arginine methyl ester (L-NAME). Hydrogen sulfide (H2S) has been shown to participate in endothelium-dependent relaxation of small resistance arteries. Therefore, this study aimed to investigate whether endothelial H2S-dependent signaling plays a role in the vasorelaxation in response to MOE. Mesenteric arterial beds isolated from L-NAME hypertensive rats were set up in an exvivo perfusion system for measurement of vasoreactivity. All experiments were performed in the presence of the nitric oxide synthase inhibitor, L-NAME (100µM) and the cyclooxygenase inhibitor, indomethacin (10µM) to prevent the formation of nitric oxide and prostanoids, respectively. In the presence of the nitric oxide synthase inhibitor, L-NAME and the cyclooxygenase inhibitor, indomethacin, the endothelium-dependent vasorelaxation induced by MOE (0.001-3mg) was completely inhibited by DL-propargylglycine (100µM), which inhibits the H2Sgenerating enzyme, cystathionine γ-lyase. This H2Sdependent response was reduced by the KATP channel blocker; glibenclamide (10µM), the KCa channel blocker; tetraethylammonium (1µM), and the myo-endothelial gap-junctional uncoupler; 18α-glycyrrhetinic acid (10µM). In contrast, the muscarinic receptor antagonist, atropine (100µM), did not affect the response to MOE. The results may suggest that H2S is the likely mediator of endothelium-dependent relaxation in response to MOE in mesenteric arterial beds of L-NAME-induced hypertensive rats. MOE-induced H2S-dependent vasorelaxation involves activation of KATP and KCa channels and requires myo-endothelial gap-junctional communication.

Prenatal hypoxia predisposes vascular functional and structural changes associated with oxidative stress damage and depressive behavior in adult offspring male rats

Intrauterine hypoxia-ischemia (HI) provides a strong stimulus for a developmental origin of both the central nervous system and cardiovascular diseases. This study aimed to investigate vascular functional and structural changes, oxidative stress damage, and behavioral alterations in adult male offspring submitted to HI during pregnancy. The pregnant Wistar rats had a uterine artery clamped for 45 min on the 18th gestational day, submitting the offspring to hypoxic-ischemic conditions. The Sham group passed to the same surgical procedure as the HI rats, without occlusion of the maternal uterine artery, and the controls consisted of non-manipulated healthy animals. After weaning, the male pups were divided into three groups: control, sham, and HI, according to the maternal procedure. At postnatal day 90 (P90), the adult male offspring performed the open field and forced swim tests. In P119, the rats had their blood pressure checked and were euthanized. Prenatal HI induced a depressive behavior in adult male offspring associated with a reduced vasodilator response to acetylcholine in perfused mesenteric arterial bed, and reduced superoxide dismutase and glutathione peroxidase activities in the aorta compared to control and sham groups. Prenatal HI also increased the vasoconstrictor response to norepinephrine, the media thickness, collagen deposition, and the oxidative damage in the aorta from adult male offspring compared to control and sham groups. Our results suggest an association among prenatal HI and adult vascular structural and functional changes, oxidative stress damage, and depressive behavior.

Moringa oleifera leaf extract enhances endothelial nitric oxide production leading to relaxation of resistance artery and lowering of arterial blood pressure

A mass of evidence has identified a promoting of nitric oxide (NO) production in endothelial cells using natural products as a potential strategy to prevent and treat hypertension. This study investigated whether the aqueous extract of Moringa oleifera leaves (MOE) could lower mean arterial pressure (MAP) and relax mesenteric arterial beds in rats via stimulating endothelium-derived NO production. Intravenous administration of MOE (1–30 mg/kg) caused a dose-dependent reduction in MAP in anesthetized rats. In rats pretreated with the NO-synthase inhibitor, Nω-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg, i.v.), the effect of MOE on MAP was significantly reduced. MOE (0.001–3 mg) induced relaxation in methoxamine (10 μM) pre-contracted mesenteric arterial beds, which was abolished by endothelium denudation. This endothelium-dependent vasorelaxation was reduced by L-NAME (100 μM) or the NO-sensitive guanylyl cyclase inhibitor, 1H- [1,2,4]-oxadiazolo-[4,3-a]-quinoxalin-1-one (10 μM). In primary human pulmonary artery endothelial cells, MOE (3–30 μg/mL) induced NO production, which was inhibited by L-NAME (100 μM) pretreatment. These findings show that MOE stimulates the endothelium-derived NO release for driving its vasorelaxation to lower arterial blood pressure. These suggest the development of MOE as a natural antihypertensive supplement.

Anti-Anaphylactic Activity of Isoquercitrin (Quercetin-3-O-β-d-Glucose) in the Cardiovascular System of Animals.

Effects of isoquercitrin (IQ) on anaphylactic responses were examined in cardiovascular systems of experimental animals. In pithed rats, IQ at 30 and 100 mg/kg (intravenous) significantly blunted both the initial hypertensive and the ensuing hypotensive responses during anaphylaxis. Death rate and tachycardia were also significantly inhibited after the same IQ doses in these rats. In isolated guinea pig hearts, IQ infusion at 30–100 μg/mL markedly reduced anaphylaxis-related coronary flow decrease, contractile force change, and heart rate responses (both tachycardia and arrhythmia). Cardiac histamine and creatine kinase releases were similarly diminished by IQ during anaphylaxis in the isolated guinea pig hearts. In two different isolated guinea pig vasculatures, the pulmonary artery and mesenteric arterial bed, anaphylactic vasoconstriction was reduced by IQ 30 and 100 μg/mL. It was observed that IQ had a marked inhibitory effect on histamine release from rat mast cells, and this mechanism was suggested as the major anti-anaphylactic mechanism. Direct inhibition of histamine-induced muscle contraction did not seem to be relevant, but IQ treatment successfully repressed intracellular calcium influx/depletion in mast cells. Overall, this study provided evidence for the beneficial effect of IQ on cardiac anaphylaxis, thus suggesting its potential applications in the treatment and prevention of related diseases.

Moringa oleifera leaf extract induces vasorelaxation via endothelium-dependent hyperpolarization and calcium channel blockade in mesenteric arterial beds isolated from L-NAME hypertensive rats

ABSTRACT Background An aqueous extract of Moringa oleifera leaves (MOE) is known to cause relaxation of mesenteric resistance arteries of rats in which hypertension has been induced by the administration of L-NAME, but the mechanism(s) of action of MOE remains unclear. The purpose of this study was to investigate these mechanisms in mesenteric arterial beds isolated from L-NAME induced hypertensive rats. Methods: An investigation of vascular reactivity was conducted on isolated mesenteric arterial beds by measuring the changes in perfusion pressure using an in vitro system. Results MOE (0.001–3 mg in 0.1 ml injection volume) caused a dose-dependent relaxation in methoxamine (5 µM) pre-contracted arterial beds, which was partially abolished by endothelium removal. The endothelium-dependent component of vasorelaxation was insensitive to both L-NAME (100 µM) and indomethacin (10 µM), while completely inhibited in high KCl (45 mM)-induced contraction. MOE (1 and 3 mg/ml) showed a dose-dependent inhibitory effect on CaCl2-induced contractions of denuded preparations in Ca2+-free medium containing a high KCl (60 mM) or methoxamine (10 µM). In Ca2+-free medium, MOE (3 mg/ml) also inhibited phenylephrine-induced contractions of denuded preparations. Conclusion: These findings suggest that MOE relaxes mesenteric arterial beds of L-NAME hypertensive rats via both endothelium-dependent and endothelium-independent mechanisms. The endothelium-dependent action occurred via endothelium-derived hyperpolarizing factor-mediated hyperpolarization. The endothelium-independent action was related to blocking the entry of extracellular Ca2+ via voltage-operated and receptor-operated Ca2+ channels, and inhibiting mobilization of sarcolemmal Ca2+ via inositol trisphosphate receptor Ca2+ channels. MOE may be potentially useful as a natural vasodilator against hypertension.

The glucagon-like peptide 1 receptor agonist liraglutide attenuates placental ischemia-induced hypertension.

Preeclampsia is a hypertensive disorder of pregnancy characterized by systemic perturbations of nitric oxide function, reflective of generalized endothelial dysfunction. Therapies that target the nitric oxide pathway have shown promise in both clinical and preclinical studies of preeclampsia. The glucagon-like peptide 1 agonists have been shown to increase nitric oxide and lower blood pressure in patients with diabetes, in part, through activation of nitric oxide synthase (NOS). Therefore, we hypothesized that a direct acting glucagon-like peptide 1 receptor agonist would improve stigmata of the preeclampsia syndrome. Using the reduced uterine perfusion pressure rat model, we found that treatment with liraglutide significantly lowered blood pressure, improved renal function, and upregulated NOS3 protein expression in the mesenteric arterial bed. However, there were adverse effects on pup growth that were likely related to diminished food intake in the dams. Collectively, these data support the premise that the use of drugs that improve NOS abundance, including the glucagon-like peptide 1 agonists, is a rational therapeutic approach to the treatment of preeclampsia, but suggest cautious and careful study of their safety before potential clinical use in humans.NEW & NOTEWORTHY Drugs that target the glucagon-like peptide-1 pathway such as liraglutide are already used clinically, and it has been shown to promote endothelial nitric oxide synthase (NOS3) expression. We demonstrate that liraglutide, a glucagon-like peptide 1 receptor (GLP-1R) agonist, lowers blood pressure, improves renal function, and upregulates NOS3 in a rat model of placental ischemia. These data suggest that drugs that target the nitric oxide system, including GLP-1R agonists, are a potential therapeutic option for preeclampsia.

Abstract P135: Angiotensin II, But Not Methoxamine Or 5-HT, Causes ATP Release in the Rat Mesenteric Arterial Bed

The control of vascular caliber relies on mediators released from multiple components of the vascular neuroeffector junction. These mediators include ATP, which is released from the sympathetic nerves from vesicles that also contain norepinephrine, as well as from the vascular smooth muscle (VSM) via pannexin-1 (panx-1) channels. We hypothesize that VSM-derived ATP plays a critical role in balancing the vasoactive effects of mediators at the vascular neuroeffector junction. Panx-1 channel opening on VSM has been reported to be stimulated by caspase cleavage, cytoplasmic Ca 2+ , and extracellular K + , but the effects of VSM GPCR activation are not as well characterized. Here we utilize a near-real time luminometric technique to quantify the release of ATP from the rat mesenteric arterial bed in response to vasoconstrictor agonists. We observed disparate effects of three physiologically relevant vasoactive agents, and these do not correlate with the relative changes in perfusion pressure. Whereas angiotensin II caused a robust release of ATP (228.6 ± 31.94 nM), no significant release was observed with either methoxamine (an α 1 agonist; 44.41 ± 31.94 nM) or 5-HT (0 ± 0 nM) . These results indicate that GPCR-mediated smooth muscle contraction is not sufficient to induce ATP release in this vascular bed. This is an important first step toward understanding the role of ATP in the vasculature.

Potent Vasodilator and Cellular Antioxidant Activity of Endemic Patagonian Calafate Berries (Berberis microphylla) with Nutraceutical Potential.

Hydroalcoholic extracts of Patagonian Calafate berry (Berberis microphylla) contain mono or disaccharide conjugated anthocyanins and flavonols. The Liquid Chromatography-Mass Spectrometry (LC-MS) chemical extract profile identified glycosylated anthocyanidins such as delphinidin-, petunidin- and malvidin-3-glucoside as the major constituents. The predominant flavonols were 3-O substituents quercetin-rutinoside or -rhamnoside. Anthocyanins doubled flavonols in mass (13.1 vs. 6 mg/g extract). Polyphenols vascular actions were examined in the rat arterial mesenteric bed bioassay; extract perfusion elicited concentration-dependent vasodilatation mimicked by conjugated anthocyanins standards. Vascular responses of main glycosylated anthocyanins were endothelium-dependent (p < 0.001) and mediated by NO production (p < 0.05). The anthocyanins antioxidant activity determined in isolated endothelial cells (CAA) showed a reduced redox potential as compared to the extract or quercetin. While in the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay, the anthocyanins showed an equivalent quercetin potency, the extract was 15-fold less active, proposing that the anthocyanin-induced vasodilation is not due to an antioxidant mechanism. The extract shows promising commercial nutraceutical potential.

Nitric Oxide‐Mediated Nanomolar Vasodilator Potencies of Glycosylated Anthocyanins do not Correlate with Redox Potential

Calafate is an endemic Patagonian shrub (Berberis Microphylia); its berries are rich in polyphenols, including 3‐glycosylated anthocyanins (GA, delphinidin, petunidin or malvidin) or mono or disaccharide conjugated quercetin (Q). The chemical profile of Calafate berries is well characterized and indicates its high redox potential; pharmacological properties are virtually unknown. From ethno‐pharmaceutical reports we hypothesized that Calafate polyphenols are vasodilators and ascertained whether this effect is related to their cell antioxidant activity (CAA).Vascular responses of GA and Q were assessed perfusing the intact rat arterial mesenteric bed or following endothelium denudation. The role of NO was assessed in mesenteries perfused with an eNOS inhibitor (L‐NNA). Luminally accessible NO was determined by chemiluminescence; intracellular NO was quantified by DAF fluorescence in isolated mesentery endothelial cells. Antioxidant capacity was quantified either by 1,1‐Diphenyl‐2‐picryl‐hydrazyl antioxidant assay (DPPH) or by CAA assessment. Extracellular ATP was assessed by chloroacetaldehyde derivatization to yield fluorescent purines; the nucleotide is related to NO production in endothelial cells.GA proved potent vasodilators with EC50s of 84.1 ± 0.3, 65.8 ± 0.4 and 17.7 ± 0.1 nM, respectively; aglycones exhibited similar EC50s. The maximal effect of GA did not exceed 56 ± 3.7% efficacy compared to acetylcholine (EC50 was 43.4 ± 0.1 nM with 100% efficacy) while the Q EC50 was 12.8 ± 0.1 μM, with 99 ± 4.1%. The GA‐induced vasodilatation was totally endothelium‐dependent; while the Q response showed partial endothelium‐dependence. The degree of GA vasodilatation correlated with luminal NO (r2 = 0.83), confirming NO as the final intracellular signal. 30 μM Q increased both extracellular ATP secretion from endothelial cells plus intracellular DAF‐fluorescence (P&lt;0.05), an indication that part of the Q response involves NO as the final effector. While Q exhibited the highest antioxidant effect in both the DPPH or CAA (p&lt;0.01), the GA showed a 60‐fold lower potential than Q in the CAA test, indicating that the CAA is not related to its vasodilator profile, which apparently relies on eNOS allosteric modulation.In sum, GA are novel and potent endothelium‐dependent vasodilators, linked to modulation of NO production.Support or Funding InformationFunded by FONDECYT 117‐0842 and 21141226 to CC and CEDENNA FB0807This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Moringa oleifera leaf extract lowers high blood pressure by alleviating vascular dysfunction and decreasing oxidative stress in L-NAME hypertensive rats

BackgroundEnhancing relaxation of resistance arteries and decreasing oxidative stress by using natural products are potential strategies for prevention and treatment of hypertension. PurposeThis study investigated whether aqueous extract of Moringa oleifera leaves (MOE) could alleviate Nω-nitro-L-arginine-methyl ester (L-NAME)-induced high blood pressure via modulation of vascular function and antioxidant properties. MethodsAn experimental hypertensive model was established by administration of L-NAME (50 mg/kg/day) in drinking water to male Wistar rats for 3 weeks. Arterial pressure was measured indirectly by tail-cuff plethysmography and directly via femoral artery catheterization. Vasoreactivity of isolated rat mesenteric arterial bed was determined by the changes in perfusion pressure detected by a pressure transducer. Vascular superoxide anion (O2•−) production was determined by lucigenin-enhanced chemiluminescence. Other biochemical measurements including malondialdehyde (MDA) level, superoxide dismutase (SOD), and catalase (CAT) activities were measured by colorimetric assay. ResultsL-NAME-treated rats developed significantly increased blood pressure and heart rate. Concurrent oral treatment with MOE (30 and 60 mg/kg/day) could decrease the high blood pressure and tachycardia in a dose-dependent manner. MOE reduced the impairment of acetylcholine-induced relaxation and decreased the hyperreactivity of adrenergic-mediated contraction in response to periarterial nerve stimulation and phenylephrine in isolated mesenteric arterial beds. In addition, MOE exhibited antioxidant effects in the hypertensive rats, as indicated by suppression of vascular O2•− production, decrease of plasma and thoracic aorta MDA levels, and increase of antioxidant activities of SOD and CAT. Moreover, MOE (0.001–0.3 mg) produced a dose-dependent relaxation in methoxamine pre-contracted arterial beds isolated from L-NAME hypertensive rats, which was abolished by endothelium denudation. ConclusionThese findings suggest that the antihypertensive effect of MOE in L-NAME-hypertensive rats may be mediated by alleviating vascular dysfunction and oxidative stress and promoting endothelium-dependent vasorelaxation. MOE may be potentially useful as a natural product against hypertension.

Endothelium-Independent Vasorelaxant Effect of Synthesized 2 Hydroxymethylchromone on Rat Mesenteric Arterial Bed

Background: Several synthesized chromones derivatives have been found to promote intense vasodilation and antihypertensive activity. 2 hydroxymethylchromone (2HMC) is a benzopyrane derivative that vasodilator effect on small arteries has not yet been investigated. This study describes its synthesis, examines any vasodilator effect observed, and clarifies its mechanism of action in rat mesenteric arterial bed (MAB). Material and Method: Intact and denuded rat mesenteric arterial bed pre-contracted with PHE (2-4 ng/mL) was exposed to bolus injections of 2HMC (3-1000 µg). The effect of the latter was also studied in the presence of specific inhibitors such as L-NAME, indomethacine, atropine, glybenclamide, tetraethylammonium, BaCl2 and apamin. The effect of 2HMC on restricted calcium influx and calcium release from sarcoplasmic reticulum was investigated. Results: The data show that bolus injections of 2HMC induced in a dose dependent manner, a reversible vasorelaxant effect on pre-contracted preparations. This effect remained unaltered by endothelium removal and was not significantly affected by L-NAME, indomethacine, atropine, glybenclamide, BaCl2 tetraethylammonium or apamin. On the contrary, 2HMC significantly shifted to the right the concentration-response curve to high K+-induced MAB contraction during Ca2+ supplementation. Also, 2HMC strongly reduced the response to PHE when the MAB(s) were maintained under calcium-free conditions. Conclusion: Our results suggest that 2HMC-induced vasorelaxation is not mediated via the endothelium pathways, but rather might be due at least to both antagonistic action on extracellular calcium influx (blockade of voltage operated calcium channels) and restriction of calcium mobilization from intracellular stores. Keywords: Chromones, 2-hydroxymethyl-4H-1-benzopyran-4-one, endothelium-independent, vasodilatation, rat mesenteric arterial bed, VOCCs blockade, restriction of intracellular Ca2+ release, perfusion pressure, smooth muscle.