Mesenteric Rings Research Articles

Vasorelaxant Effect and Blood Pressure Reduction Potential of Pitaya Juice Concentrate (Stenocereus huastecorum) Associated with Calcium Channel Blockade.

Arterial hypertension is a highly prevalent chronic disease worldwide, with several etiologies and treatments that may eventually have side effects or result in patients developing tolerance. There is growing interest in traditional medicine and functional foods to isolate biomolecules that could be useful as coadjuvants for treating several aliments. Pitaya, a desert fruit endemic in Mexico, is a rich source of bioactive molecules (betalains and phenolic compounds). In this work, the vasorelaxation properties of pitaya juice concentrate and fraction one were investigated using aortic and mesenteric rings from rats. The incubation of rings with pitaya juice concentrate or fraction one induced significant vasorelaxation, independent of the endothelium, and showed resistance to potassium channel blockers. This vasorelaxation was associated with the transmembrane influx of extracellular calcium through the vascular smooth muscle cells, with an inhibitory effect on the voltage-dependent calcium channel currents. Also, 400 mg/mL of pitaya juice concentrate in spontaneous hypertensive rats reduced their blood pressure for 48 h. Phytochemical analyses showed that the primary compounds in F1 were glycosidic in nature, and could be a complex mixture of disaccharides, dimeric disaccharides, or even tetrasaccharides. The glycosidic compounds found in F1 primarily contributed to vasodilatation, establishing a voltage-dependent calcium channel inhibition as a possible molecular target.

Preferential vasodilator effects of levosimendan in resistance pulmonary arteries in a rodent pulmonary embolism model

Background: We compared the vasoactive effects of levosimendan on isolated conduit pulmonary arteries (CPA) and resistance pulmonary arteries (RPA) versus mesenteric arteries, and we assessed the pulmonary artery (PA) vascular function and the PA vasoactive effects of levosimendan in a rodent pulmonary embolism (PE) model.Methods: One group of male Wistar rats (200-300 g) was killed by decapitation to obtain pulmonary and mesenteric rings. Another group was assigned to a massive PE or saline solution infusion. After euthanasia, mesenteric arteries and CPA (1-2 mm) and RPA (≤0.5 mm) were dissected and cut into 2-3 mm wide rings, recording contractile tension. We obtained the concentration-response curves of cumulative doses of levosimendan on pre-contracted arterial rings from decapitated and sham/embolized animals. A set of RPA rings was exposed to acute hypoxia. The effect of PE on the pulmonary vasoactive function was assessed by dose-response curves of acetylcholine (ACh) and endothelin-1 (ET-1) of PA rings from sham/embolized animals.Results: Levosimendan relaxant potency of RPA was similar to that of mesenteric arteries and higher than CPA, while mesenteric rings showed the maximal relaxant effect, followed by RPA and CPA, respectively. PE did not affect the vasoactive response of PA rings either to ACh or to ET-1, and the relaxant effects of CPA and RPA to levosimendan were also preserved. Acute hypoxia reduced (p<0.05) but did not avoid the RPA relaxant effect of levosimendan.Conclusions: Levosimendan is a more specific vasodilator of RPA with a similar relaxant potency as mesenteric arteries, which is preserved after PE but significantly reduced during hypoxia.

An Evolutionarily Conserved Olfactory Receptor Is Required for Sex Differences in Blood Pressure

Olfactory receptor 558 (Olfr558) is expressed in the kidney where its functional role is unknown. Using RNAScope, we find that Olfr558 localizes to vascular smooth muscle, including the renal afferent arteriole. Thus, we measured blood pressure (BP) in Olfr558 wild-type (WT) and knockout (KO) mice. Systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP) were measured in whole-body Olfr558 wild-type (WT) and knockout (KO) via telemetry. It is known that males have a higher BP than premenopausal females in both humans and mice; indeed, we find Olfr558WT males (M) have higher BP than females (F, n=7-9 per group), including MAP (M:101.0±1.6 vs. F:89.0±0.9 mmHg, p<0.0001), SBP (M:113±2 vs. F:102±1mmHg, p=0.0025), and DBP (M: 89±2 vs. F:75±01mmHg, p<0.0001). However, sex differences in BP are entirely absent in Olfr558 KO (MAP M: 96±2 vs. F: 95±1mmHg; SBP M: 110±2 vs. F: 108±2mmHg; DBP M: 81±2 vs. F: 82±2mmHg). Of note, other sex differences (body weight) are intact in KO, and KO males and females are fertile. To characterize this phenotype, renin expression was analyzed by qPCR, plasma renin activity (PRA) was measured by ELISA, and vasoreactivity was examined ex vivo by wire myography (responses to potassium chloride (KCl), phenylephrine (PE), acetylcholine (Ach), and sodium nitroprusside (SNP) in aortic and mesenteric rings). In male KOs (n=10-12), there was a decrease in kidney renin mRNA (0.4±0.1 vs WT: 1±0.1 p=0.001) and PRA (201±21 vs WT: 402±15, p=0.001); these parameters were unchanged in female KOs. Male KO aortic rings exhibit less constriction to PE, male KO mesenterics exhibit more relaxation to SNP, and female KO aortic rings exhibit more constriction to KCl. In females, pulse wave velocity (PWV) and tensile testing revealed that KO females have increased PWV (KO: 4.6±0.4 vs WT: 3.2±0.2 m/s, p=0.0069, n=8-11), but no changes in tensile testing. The human ortholog of Olfr558, OR51E1, was previously identified as a locus associated with DBP. Using UK Biobank data (N~450k), we find that a rare OR51E1 missense variant has a statistically significant sex interaction effect with DBP ( p=0.015), increasing DBP (+6.28mmHg) in women but decreasing it (-4.77mmHg) in men (similar to the phenotype in M and F Olfr558 KO mice). Finally, we express OR51E1 variants in HEK 293T cells and characterize how two different clinically relevant OR51E1 variants influence OR51E1 signaling. In sum, our findings demonstrate that an evolutionarily conserved olfactory receptor is required for sex differences in BP. Olfr558 regulates BP in males via renin and vascular reactivity, but via arterial stiffness in females. Funding: R56DK107726 This is the full abstract presented at the American Physiology Summit 2023 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.

Salvianolic acid A from Danhong Injection induces vasorelaxation by Regulating L-type calcium channel in isolated mouse arteries

Ethnopharmacological relevanceDanhong injection (DHI), which is a Chinese clinical prescription consists of Radix et Rhizoma Salviae Miltiorrhizae (Salvia miltiorrhiza Bge., Labiatae, Danshen in Chinese) and Flos Carthami (Carthamus tinctorius L., Compositae, Honghua in Chinese)(Plant names have been checked with http://www.theplantlist.org on March 1st, 2022), has been mainly used in the clinical therapy of cardiovascular diseases, including hypertension in China for many years. Aim of the studyCardiovascular diseases (CVDs) are the major causes of death all around the world. Due to the various stimulation, a series of vasoconstrictor substances are secreted to regulate the vasoconstriction function and then change blood pressure. The representative substances leading to abnormal vasoconstriction include renin-angiotensin system, endothelin, vasopressin and adrenaline, which act on the corresponding receptors on vascular smooth muscle to constrict blood vessels. Finally, blood pressure increases, followed by a series of cardiovascular diseases, including hypertension. However, little is known about Danhong injection’s specific vasodilating mechanisms and active substances. The aims of the study were to determine the vasodilating substances of Danhong injection and explain its molecular mechanism of vasodilation. Materials and methodsThe effects of DHI and its active components on vascular tension were measured by myograph system in the aortic or mesenteric rings of mice. Based on this, the pharmacodynamic substances were analyzed and effective molecules were found. Combined with multiple types of vascular myograph experiments and network pharmacological analysis, the molecular pathway was preliminarily determined. With molecular biology experiments, it was verified that the relevant mechanisms were closely related to calcium-mediated vasoconstriction in smooth muscle cells. ResultsDHI could relax endothelium-removed aortic rings pre-constricted with PE and 3 possible active vasodilator substances, including salvianolic acid A, salvianolic acid B and danshensu, were screened out by network pharmacology and vascular myograph experiments, among which the effects of salvianolic acid A were dominant. Meanwhile, salvianolic acid A could dilate mesenteric artery in a pressure-dependent manner. Interestingly, salvianolic acid A could still relax the vascular rings under the stimulation of KCl and Bayk8644, two agonists of L-type calcium channel. By contrast, inhibitors of Kir, Kv, Katp and BKCa channels did not block the effect of salvianolic acid A on vasodilation. Salvianolic acid A alleviated Ca2+ transient, referring to changes of intracellular calcium, induced by PE, Bayk8644 and high K+ in the VSMCs. Salvianolic acid A could partially restore the vasodilation function of vascular smooth muscle damaged by AngII and ET-1 induced hypertension situation. ConclusionsOur results indicate that salvianolic acid A is the major vasodilator substance in DHI and the vasorelaxation pharmacology mechanism involved in inhibiting the L-type calcium channel signaling in smooth muscle cell. Hence, there are potential therapeutic effects of taking salvianolic acid A preparation which may be beneficial to protect cardiovascular system and reduce blood pressure.

Role of the High‐Conductance Calcium‐Activated Potassium Chanel in first order mesenteric artery of hypercaloric diet rat model

Obesity has been identified like as a risk factor of metabolic syndrome. The High‐Conductance Calcium‐Activated Potassium Channel (BKCa) in vascular smooth muscle cells regulates membrane potential and control myogenic tone.Objectiveevaluated the role of the BKCa channel in first order mesenteric arteries of rats feed with a hypercaloric diet for 18 and 28 weeks.MethodologyWe performed isometric tension experiments in first and second order mesenteric arteries rings and Patch Clamp recordings of vascular smooth muscle cells isolated of the same vascular bed.ResultsThe rats feed with a hypercaloric diet for 18 weeks shows an augmented un percentage of adipose tissue, triglycerides, glucose tolerance curve, blood pressure and more relaxation to BKCa channel activator NS11021 un rings precontracted with phenylephrine. At 28 weeks of evolution, an increase in percentage of adipose tissue with respect to body weight was observed, as well as an increase in blood pressure, Regarding BKCa channel function, an increase in current density was observed in the experimental group with respect to the control group.ConclusionChanges have been developed at the metabolic level in the groups of the hypercaloric diet, with changes in the BKCa channels, a gain of function in first order mesenteric rings of the 18 weeks group and in cells isolated from these arteries at 28 weeks group. Nevertheless, at 28 weeks of evolution, first order mesenteric artery rings no longer showed the gain in function observed in the previous group, which suggest a compensatory mechanism maybe associated to aging.

Effects of local cryotherapy on systemic endothelial activation, dysfunction, and vascular inflammation in adjuvant-induced arthritis (AIA) rats

AimThis study explored the systemic vascular effects of local cryotherapy with a focus on endothelial changes and arterial inflammation in the model of rat adjuvant-induced arthritis (AIA).MethodsCryotherapy was applied twice a day on hind paws of AIA rats from the onset of arthritis to the acute inflammatory phase. Endothelial activation was studied in the aorta by measuring the mRNA levels of chemokines (CXCL-1, MCP-1 (CCL-2), MIP-1α (CCL-3)) and adhesion molecules (ICAM-1, VCAM-1) by qRT-PCR. Endothelial dysfunction was measured in isolated aortic and mesenteric rings. Aortic inflammation was evaluated via the mRNA expression of pro-inflammatory cytokines (TNF-α, IL-6) by qRT-PCR and leucocyte infiltration analysis (flow cytometry). Plasma levels of TNF-α, IL-6, IL-1β, IL-17A, and osteoprotegerin (OPG) were measured using Multiplex/ELISA.ResultsAIA was associated with an increased aortic expression of CXCL-1 and ICAM-1 as well as an infiltration of leucocytes and increased mRNA expression of IL-6, IL-1β, and TNF-α. Local cryotherapy, which decreased arthritis score and structural damages, reduced aortic mRNA expression of CXCL-1, IL-6, IL-1β, and TNF-α, as well as aortic infiltration of leucocytes (T lymphocytes, monocytes/macrophages, neutrophils) and improved acetylcholine-induced vasorelaxation in the aorta and mesenteric arteries. Plasma levels of IL-17A and OPG were significantly reduced by cryotherapy, while the number of circulating leucocytes was not. IL-17A levels positively correlated with endothelial activation and dysfunction.ConclusionIn the AIA model, local cryotherapy reduced systemic endothelial activation, immune cell infiltration, and endothelial dysfunction. Mechanistically, the reduction of circulating levels of IL-17A appears as the possible link between joint cooling and the remote vascular effects.

Vasorelaxant Effect Induced by the Essential Oil of Ocotea duckei Vattimo Leaves and Its Main Constituent, Trans-caryophyllene, in Rat Mesenteric Artery

Aims: To evaluate the vasorelaxant effect induced by the essential oil of the leaves of O. duckei Vattimo (ODEO) and its main constituent, trans-caryophyllene, in rat superior mesenteric arteries.
 Methodology: Isolated rat superior mesenteric rings were suspended by cotton threads for isometric tension recordings in Tyrode’s solution at 37ºC, gassed with 95% O2 and 5% CO2 and different ODEO concentrations (0.1-300 μg/mL) or trans-caryophyllene (1-1000 μg/mL) were added cumulatively to the organ baths.
 Results: Vasorelaxant effect induced by the essential oil of Ocotea duckei leaves (ODEO) and its main constituent, trans-caryophyllene (60.54 %), was evaluated in this work. In intact isolated rat superior mesenteric rings ODEO (0.1-300 μg/mL, n=6) induced concentration-dependent relaxation of tonus induced by phenylephrine (10 µM) or K+-depolarizing solution (KCl 80 mM) (IC50=31±5, 5±0.4 µg/mL, respectively, n=6). The relaxations of phenylephrine-induced contractions were not significantly attenuated after removal of the vascular endothelium (IC50=25±5 µg/mL). ODEO antagonized the concentration-response curves to CaCl2 (10-6-3x10-2 M) and Bay K 8644 (10-10-3x10-6 M). Furthermore, in nominally without calcium solution, ODEO significantly inhibited, in a concentration-dependent manner, transient contractions induced by 10 µM phenylephrine or 20 µM caffeine. Trans-caryophyllene induced vasorelaxations, however, this effect was 18.6 times less potent when compared to ODEO-induced vasorelaxations.
 Conclusion: The relaxant effect induced by ODEO in rat superior mesenteric artery rings is endothelium-independent and seems to be related to both, inhibition of Ca2+ influx through L-type voltage-gated Ca2+-channels sensitive to dihydropyridines and inhibition of the calcium release from intracellular IP3-and caffeine-sensitive stores.

Terminalia avicennioides causes redox-sensitive endothelium-dependent relaxation involving nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing in porcine coronary artery and different conductance and resistance vessels from rats

Background: Our work is part of the enhancement of plants of Senegalese pharmacopeia with cardiovascular aim, among which Terminalia avicennioides. Aim and Objective: The aim of this study was to determine whether a hydroethanolic bark extract of T. avicennioides (TAE) is able to induce a relaxant effect in porcine coronary, rat mesenteric artery, carotid, femoral arteries, and thoracic aorta and to determine the mechanism underlying this effect. Materials and Methods: Porcine coronary, rat mesenteric, carotid, femoral arteries, and thoracic aorta rings were suspended in organ chambers for the recording of changes in isometric forces. Rings with endothelium were incubated or not with L-Nitro Arginine to block nitric oxide (NO) synthase, MnTMPyP, polyethylene glycol catalase (CAT), an inhibitors of intracellular production reactive oxygen species; CAT, an inhibitor of extracellular reactive oxygen species; Wortmannin, an inhibitor of redox-sensitive pathway PI3 kinase/Akt; PP2 (4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo [3,4-d]pyrimidine), an inhibitor of Src kinase; apamin (APA) an inhibitor of small conductance potassium channels calcium-dependent (SKCa) and Tram-34 an inhibitor of intermediary conductance potassium channels calcium-dependent (IKCa); and indomethacin (INDO), an inhibitor of cyclooxygenase before contraction with U46619 or phenylephrine (PE) and a concentration relaxation curve to TAE. In some experiments, the endothelium was removed before contraction with U46619 or PE and concentration relaxation to TAE. The phosphorylation level of Akt and eNOS was assessed by Western blot analysis. Results: The hydroethanolic bark TAE induces a vasodilatory effect in porcine coronary artery precontracted with U46619. This effect is endothelium-dependent and is mediated by NO, prostaglandin, and endothelium-derived hyperpolarizing. TAE also induces vasorelaxant effects in superior mesenteric arteries, carotid arteries, thoracic aorta, and femoral arteries from rat. Conclusion: TAE-induced sustaining phosphorylation of Akt and eNOS in endothelial cells. T. avicennioides induces vascular relaxation which can explain the benefic effect of this plant in the treatment of high blood pressure in Senegal.

Antihypertensive activity of diethyl-4,4ʹ-dihydroxy-8,3ʹ-neolign-7,7ʹ-dien-9,9ʹ-dionate: A continuation study in L-NAME treated wistar rats

In the present study, we report that neolignan1 (Diethyl-4,4ʹ-dihydroxy-8,3ʹ-neolign-7,7ʹ-dien-9,9ʹ-dionate) relaxes the superior mesenteric artery in a concentration dependent manner (pD2 value 5.392 ± 0.04; n = 8 for endothelium intact and 5.204 ± 0.03; n = 8 for endothelium denuded mesenteric rings, respectively). The relaxation response of neolignan1 was found to be endothelium independent and sensitive to 1H-[1,2,4] oxadiazolo [4,3-a]quinoxalin-1-on (ODQ; 1 μM) and tetraethyl ammonium (TEA; 1 mM). In-silico studies showed good LibDock score (92.66) of neolignan1 with BKCa channel and are in well corroboration with ex-vivo study. Further, neolignan1 significantly decreased the systolic blood pressure, diastolic blood pressure and mean arterial pressure in the Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME; 50 mg/kg) treated Wistar rats at the dose of 30 and 100 mg/kg given once orally for 15 days. In addition, neolignan1 is well tolerated up to 100 mg/kg when given as a repeated dose, once orally for 28 days in Swiss albino mice. Neolignan1 was well absorbed from oral route, reached peak at 4 h and eliminated below detection level by 12 h after administration. Our present study concludes that neolignan1 produced relaxation in superior mesenteric artery by opening of BKCa channel and produced significant antihypertensive activity in L-NAME treated Wistar rats and was well tolerated by the experimental animal.

Vasoactive properties of Ceiba pentandra in porcine coronary artery and different conductance and resistance vessels from rats: A role of nitric oxide

Background: Ceiba pentandra (L.) Gaertner (Malvaceae) a plant widely spread in the world, particularly in sub-Saharan Africa where it is used to handle several pathologies like high blood pressure without scientific evidence by experimental scientific works. Aim and Objective: The purpose of this study is to show how a hydroethanolic leaves extract of Ceiba pentandra (FCP) produces relaxant effects in porcine coronary, rat mesenteric artery, carotid, femoral arteries, and thoracic aorta and to determine the mechanisms which lie beneath this effect. Materials and Methods: Porcine coronary, rat mesenteric, carotid, and femoral arteries and thoracic aorta rings were suspended in organ chambers for recording of changes in isometric forces. Rings with endothelium were incubated or not with L-nitroarginine to block nitric oxide (NO) synthase, manganese (III) tetrakis(1-methyl-4-pyridyl)porphyrin, polyethylene glycol catalase (CAT), an inhibitors of intracellular production reactive oxygen species (ROS); CAT, an inhibitor of extracellular ROS; wortmannin, an inhibitor of redoxsensitive pathway phosphoinositide 3-kinase (PI3 kinase)/Akt; (4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo [3,4-d] pyrimidine), an inhibitor of Src kinase; apamin, an inhibitor of small conductance potassium channels calcium dependent (SKCa) and tram-34, an inhibitor of intermediary conductance potassium channels calcium dependent (IKCa); and indomethacin, an inhibitor of cyclooxygenase before contraction with U46619 or phenylephrine and a concentration-relaxation curve to FCP. Results: Some experiments show that endothelium was taken away before contraction with U46619 and concentration relaxation to FCP. The hydroethanolic leaves extract of C. pentandra produces a vasodilatory result in porcine coronary artery pre-contracted with U46619. This effect is endothelium dependent and is mediated by NO. FCP generates, as well, vasorelaxant results in superior mesenteric arteries, carotid arteries, thoracic aorta, and femoral arteries from rat. C. pentandra generates vascular relaxation which can be the explanation of the benefic effect of this plant in the treatment of high blood pressure (HBP) in Africa. Conclusion: C. pentandra holds vasorelaxants properties on pig coronary artery, thoracic aorta, the main superior mesenteric artery, and femoral and carotid artery from rat justifying its utilization in the treatment of the arterial HBP. This effect necessitates the presence of a functional endothelium and passes by the redox-sensitive pathway Src kinase and PI3-kinase/Akt.

Vasorelaxant activity and acute toxicity of the ethanolic extract of Zanthoxylum rhoifolium Lam leaves

The study evaluated the vasorelaxant effect induced by the ethanolic extract of the leaves of Zanthoxylum rhoifolium Lam (EEtOH-Zr/leaves). Wistar rats were treated with the leaf extract containing a single dose of 2,000 mg / kg, v.o. After 14 days, the animals were anesthetized for blood collection and subsequent analysis of the biochemical parameters; they were then euthanized (sodium pentobarbital-100 mg/kg, i.p.) for the removal and morphological analysis of the heart, lung, liver and kidney. The vasorelaxation activity the and vascular reactivity of EEtOH-Zr/leaves were evaluated on artery mesenteric rings isolated from rats. The extract showed no signs of toxicity and no significant difference in the values of the biochemical parameters between the control group and the group of treated animals. In the evaluation of pharmacological activity in the smooth muscle, the EEtOH-Zr/leaves caused vasorelaxant effect on the tonic contraction induced by phenylephrine in mesenteric artery preparations in the presence (pD2=2.17±0.05 µg/mL; Emax=99.8±5.2%) and absence (pD2=2.14±0.05 µg/mL; Emax=95.3±6.4%) of the vascular endothelium. Oral administration of EEtOH-Zr/leaves reduced the contraction induced by the cumulative addition of PHE. It is concluded that the EEtOH-Zr/leaves promote vasorelaxation and reduce vascular reactivity of adrenergic alpha-1 agonist in the mesenteric artery. The results did not show toxic effects of the extract.

Oxidative stress induced by prenatal LPS leads to endothelial dysfunction and renal haemodynamic changes through angiotensin II/NADPH oxidase pathway: Prevention by early treatment with α-tocopherol

We investigated whether hypertension induced by maternal lipopolysaccharide (LPS) administration during gestation is linked to peripheral vascular and renal hemodynamic regulation, through angiotensin II → NADPH-oxidase signalling, and whether these changes are directly linked to intrauterine oxidative stress. Female Wistar rats were submitted to LPS, in the absence or presence of α-tocopherol during pregnancy. Malondialdehyde in placenta and in livers from dams and foetuses was enhanced by LPS. Tail-cuff systolic blood pressure (tcSBP) was elevated in the 16-week-old LPS offspring. Renal malondialdeyde and protein expression of NADPH oxidase isoform 2 were elevated in these animals at 20 weeks of age. Maternal α-tocopherol treatment prevented the elevation in malondialdehyde induced by LPS on placenta and livers from dams and foetuses, as well as prevented the elevation in tcSBP and the elevation in renal malondialdehyde in adult life. LPS offspring presented impairment of endothelium-dependent relaxation in aorta and mesenteric rings, which was blunted by angiotensin type 1 receptor (AT1R) blockade and NADPH oxidase inhibition. At age of 32 weeks, renal hemodynamic parameters were unchanged in anaesthetised LPS offspring, but angiotensin II infusion led to an increased glomerular filtration rate paralleled by filtration fraction elevation. The renal haemodynamic changes provoked by angiotensin II was prevented by early treatment with α-tocopherol and by late treatment with NADPH oxidase inhibitor. These results point to oxidative stress as a mediator of offspring hypertension programmed by maternal inflammation and to the angiotensin II → NADPH oxidase signalling pathway as accountable for vascular and renal dysfunctions that starts and maintains hypertension.

Endothelium alteration is a key process in the development of heart failure with preserved ejection fraction

Endothelial has been suggested to play an important role in the development of heart failure with preserved ejection fraction (HFpEF), but there is no real link so far. Mechanism could involve alteration in vascular structure and reactivity. •NO bioavailability has been suggested to play a central role in this phenomenon and •NO production is partly mediated through β3-adrenoreceptor (β3-AR) activation. Our team developed a transgenic rat (Tgβ3) overexpressing the human β3-AR in the endothelium leading with ageing to HFpEF. The aim of our study was to understand the implication of the endothelium in HFpEF development. Aorta from 45 weeks old rat have been used to evaluate arterial reactivity (aorta and mesenteric rings). Endothelium-dependent relaxation to isoproterenol (0.1 nM to 100 μM) was measured in the presence or absence of •NO synthase (NOS) inhibitors: L-VNIO (NOS-1), 1400 W (NOS-2) and L-NIO (NOS-3) at 10 μM. •NO production in aorta has been evaluated by electron paramagnetic resonance (EPR). Concentration-dependent vasodilation to isoproterenol was significantly reduced in Tgβ3 aorta and mesenteric arteries (−10%, P < 0.05 vs. WT) indicating an alteration of endothelial function. With NOS-2 inhibitor, concentration-dependent vasodilation to isoproterenol was unchanged, but vasodilation in presence of NOS-1 and NOS-3 inhibitors was significantly reduced in Tgβ3. Interestingly, vascular production of •NO was increase in Tgβ3 rats (+91%, P < 0.05 vs. WT) while, the main NOS responsible to •NO production, NOS-3, was significantly decreased (−19%, P < 0.05 vs. WT). Our animal model demonstrates for the first time that alteration of the endothelial function could lead to HFpEF development. This observation could lead a better understanding of HFpEF pathophysiology, yet evolution of vascular function and •NO production need to be evaluated at different time of HFpEF development.

N-Salicyloyltryptamine, an N-Benzoyltryptamine Analogue, Induces Vasorelaxation through Activation of the NO/sGC Pathway and Reduction of Calcium Influx.

Benzoyltryptamine analogues act as neuroprotective and spasmolytic agents on smooth muscles. In this study, we investigated the ability of N-salicyloyltryptamine (STP) to produce vasorelaxation and determined its underlying mechanisms of action. Isolated rat mesenteric arteries with and without functional endothelium were studied in an isometric contraction system in the presence or absence of pharmacological inhibitors. Amperometric experiments were used to measure the nitric oxide (NO) levels in CD31+ cells using flow cytometry. GH3 cells were used to measure Ca2+ currents using the whole cell patch clamp technique. STP caused endothelium-dependent and -independent relaxation in mesenteric rings. The endothelial-dependent relaxations in response to STP were markedly reduced by L-NAME (endothelial NO synthase—eNOS—inhibitor), jHydroxocobalamin (NO scavenger, 30 µM) and ODQ (soluble Guanylyl Cyclase—sGC—inhibitor, 10 µM), but were not affected by the inhibition of the formation of vasoactive prostanoids. These results were reinforced by the increased NO levels observed in the amperometric experiments with freshly dispersed CD31+ cells. The endothelium-independent effect appeared to involve the inhibition of voltage-gated Ca2+ channels, due to the inhibition of the concentration-response Ca2+ curves in depolarizing solution, the increased relaxation in rings that were pre-incubated with high extracellular KCl (80 mM), and the inhibition of macroscopic Ca2+ currents. The present findings show that the activation of the NO/sGC/cGMP pathway and the inhibition of gated-voltage Ca2+ channels are the mechanisms underlying the effect of STP on mesenteric arteries.

Hypotensive, vasorelaxant and antihypertensive activities of the hexane extract of Anacardium occidentale Linn

Anacardium occidentale is widely used in folk medicine in Brazil, India, and Africa to treat inflammation, diabetes and hypertension. The aim of the study was to assess the hypotensive, vasorelaxant and antihypertensive effects produced by the hexane extract from the leaves of A. occidentale (HEAO) in rats. The animals were anesthetized, and polyethylene catheters were embedded into the lower abdominal aorta and the inferior vena cava for blood pressure measurements and drug administration. The HEAO was injected and the mean arterial pressure and heart rate were measured. The effects of the HEAO on isolated rat mesenteric rings with and without endothelium were investigated. HEAO induced hypotension and bradycardia in normotensive rats. After pretreatment with L-NAME, indomethacin, atropine or hexamethonium, these effects were attenuated. In mesenteric rings, HEAO antagonized the contractile effects induced by phenylephrine or KCl. This effect was inhibited after removal of the vascular endothelium. Oral administration of the HEAO decreased significant mean arterial pressure in spontaneously hypertensive rats. Mass spectrometric analysis of HEAO identified malic acid and quercetin. Our findings demonstrate that HEAO produces hypotension probably due to a reduction in peripheral vascular resistance, mediated by the endothelium, in part, by a decrease in cardiac output. Bradycardia appears to be due to the indirect activation of cardiac muscarinic receptors via activation of the vagus nerve. The HEAO also induces an antihypertensive effect.

Antioxidant and vasorelaxant activities induced by northeastern Brazilian fermented grape skins

BackgroundIn northeastern Brazil, grape pomace has become a potential alternative byproduct because of the recover phenolic compounds from the vinification process. Comparative analyses were performed between lyophilized extract of grape skins from pomace, described as fermented (FGS), and fresh, unfermented (UGS) grape skins to show the relevant brand’s composition upon the first maceration in winemaking.MethodsThe use of in vitro testing such as Folin-Ciocalteu’s, DPPH free radical scavenger and HPLC methods were performed to evidence antioxidant effect and phenolic compounds. Additionally, vascular reactivity studies were performed in third-order branches of rat superior mesenteric arteries, which were obtained and placed in organ baths containing Krebs-Henseleit solution, maintained at 37 °C, gassed with a mixture of 95% O2 and 5% CO2, and maintained at pH 7.4. The in situ formation of reactive oxygen species (ROS) was evaluated in small mesenteric rings using oxidative fluorescent dihydroethidium dye.ResultsWe found higher phenolic content and antioxidant activity in FGS when compared to UGS. HPLC analyses identified a significant number of phenolic compounds with antioxidant potential in both samples. The vasorelaxant effect induced by FGS was more potent than that induced by UGS, and the activity was attenuated after removal of vascular endothelium or by blockade of endothelium-derived relaxing factors, such as NO and EDHF.ConclusionsThe FGS extract may be a great source of natural polyphenol products with potent antioxidant effects and endothelium-dependent vasodilatory actions involving NO and EDHF pathways.

Preferential Vasodilator Effects of Levosimendan in Resistance Pulmonary Arteries in a Rodent Pulmonary Embolism Model

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; We compared the vasoactive effects of levosimendan on isolated conduit (CPA) and resistance (RPA) pulmonary arteries versus mesenteric arteries and we assessed the PA vascular function and the PA vasoactive effects of levosimendan in a rodent PE model.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods:&lt;/strong&gt; One group of male Wistar rats (200-300 g) was killed by decapitation to obtain pulmonary and mesenteric rings. Another group was assigned to a massive PE or saline solution infusion. After euthanasia mesenteric arteries and CPA (i.d. 1-2 mm) and RPA (≤ 0.5 mm) were dissected and cut into 2-3 mm wide rings recording contractile tension. We obtained the concentration-response curves of cumulative doses of levosimendan on pre-contracted arterial rings from decapitated and sham/embolized animals. A set of RPA rings was exposed to acute hypoxia. The effect of PE on the pulmonary vasoactive function was assessed by dose-response curves of acetylcholine (ACh) and endothelin-1 (ET-1) of PA rings from sham/embolized animals. &lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results:&lt;/strong&gt; Levosimendan relaxant potency of RPA was similar to mesenteric arteries and higher than CPA, while mesenteric rings showed the maximal relaxant effect, followed by RPA and CPA, respectively. PE did not affect the vasoactive response of PA rings either to ACh or to ET-1, and the relaxant effects of CPA and RPA to levosimendan were also preserved. Acute hypoxia reduced (&lt;em&gt;P&lt;/em&gt;&amp;lt;0.05) but did not avoid the RPA relaxant effect of levosimendan.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;Levosimendan is a more specific vasodilator of RPA with a similar relaxant potency as mesenteric arteries, which is preserved after PE but significantly reduced during hypoxia.&lt;/p&gt;

Endothelium-independent vasodilator effect of 2-nitro-1-phenyl-1-propanol on mesenteric resistance vessels in rats

2-Nitro-1-phenyl-1-propanol (NPP) is a nitro alcohol with vasodilator activity in the rat aorta. The present study investigated the vasodilator properties of NPP in small vessels of the mesenteric bed, which, contrary to the aorta, contains resistance vessels. Using myography, isometric contractions were recorded in rings of second- and third-order branches from the rat mesenteric artery. NPP relaxed mesenteric ring preparations that were contracted with phenylephrine, U-46619, and KCl (40mM), resulting in significantly different EC50 values (0.41μM [0.31–0.55μM], 0.16μM [0.10–0.24μM], and 4.50μM [1.86–10.81μM], respectively). NPP-induced vasodilation decreased as the extracellular K+ concentration increased. The pharmacological blockade of K+ channels with tetraethylammonium, BaCl2, CsCl, and apamin also blunted NPP-induced vasorelaxation. In contrast, NPP-induced vasodilation was resistant to indomethacin, L-NG-nitroarginine methyl ester (L-NAME), and endothelium removal, indicating that neither prostaglandins nor the endothelial release of nitric oxide is involved in the relaxant effects of NPP. Conversely, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), cis-N-(2-phenylcyclopentyl)-azacyclotridec-1-en-2-amine hydrochloride (MDL-12,330A), and H-89 reduced NPP-induced vasodilation. Under Ca2+-free conditions, NPP did not alter transient contractions that were evoked by caffeine, but it reduced transient contractions that were evoked by phenylephrine. In mesenteric rings that were loaded with the fluorescent Ca2+ indicator Fluo-4 AM and stimulated with phenylephrine, NPP blunted both contractions and fluorescence signals that were related to cytosolic Ca2+ levels. In conclusion, the vasodilatory actions NPP on mesenteric vessel resistance involved the participation of cyclic nucleotides and the opening of K+ channels.

Hypotensive and vasorelaxant effect of Diapocynin in normotensive rats

Nicotinamide adenine dinucleotide phosphate oxidase (NAD(P)H-oxidase) is a multicomponent enzyme system that generates superoxide anion by one-electron reduction of molecular oxygen and represents the major source of reactive oxygen species (ROS) in the vascular cells. Apocynin has been extensively used as an inhibitor of NADPH oxidase (NOX) in phagocytic cells and as an antioxidant in non-phagocytic cells. In phagocytes cells, due to the presence of myeloperoxidase, apocynin can be the converted to diapocynin, which is supposed to be the active form of this phytochemical. Moreover, apocynin was shown to induce hypotension and vasodilatation in many experimental animal models. However, there are no studies showing the effects of diapocynin on blood pressure or in vascular cells. In this present study, we used chemically synthesized diapocynin and analyzed its antioxidant capacity, effect on blood pressure and vascular reactivity. Moreover, it was evaluated the levels of nitric oxide (NO), ROS and calcium in aortic endothelial cells stimulated by diapocynin. All results were compared to apocynin. We found that diapocynin showed higher antioxidant capacity than apocynin. Apocynin and diapocynin, promoted hypotensive effects without changing the heart rate, however the effects of diapocynin were reversed faster than the effects of apocynin, which was long lasting. Diapocynin and apocynin induced endothelium dependent and independent vasodilatation, but diapocynin was less potent than apocynin regarding the capacity of induction of vasodilatation in mesenteric resistance arteries and aorta from Wistar rats. The relaxation induced by apocynin or diapocynin involves sGC and potassium channels in vascular smooth muscle cells and NOS participates of relaxation induced by apocynin or diapocynin in intact mesenteric rings. Apocynin and diapocynin increased NO and decreased ROS levels in endothelial cells, however diapocynin did not alter calcium levels in these cells. In conclusion, these results demonstrated that, similarly to apocynin, diapocynin also induces hypotensive and vasodilator effects in rats and vascular endothelium improves the diapocynin vasodilator effects by increases NO bioavailability.

Antihypertensive and Vasorelaxant effects of the ethanolic extract from the stem bark of Aspidosperma tomentosum Mart

Aspidosperma species have been traditionally used for the treatment of cardiovascular disease. These species are important sources of indole alkaloids, which are responsible for different cardiovascular effects. Based on this premise, and as there are still no studies related to the cardiovascular effects of the ethanolic extract from the stem bark of Aspidosperma tomentosum (EEAT). The aim of the present study was to evaluate the possible mechanism of the vasorelaxant action of EEAT in isolated rat mesenteric rings, and to establish its antihypertensive activity. The mean arterial pressure (MAP) and Heart Rate (HR) were measured in hypertensive rats through a catheter inserted in abdominal aorta via femoral artery. The vasodilator effect of EEAT in isolated pre-contracted rat mesenteric rings was examined. The bioactive extract was analyzed via mass spectrometry fingerprinting. EEAT induced relaxation in mesenteric rings pre-contracted with Phe independent of the endothelium. In denuded rings, when incubation with KCl 20 mM or TEA did not change the relaxation. EEAT inhibited the concentration-response curves induced by CaCl2 or Phe and inhibited 80 mM KCl-induced contraction. In pre-contracted preparations with BayK 8644, the EEAT induced relaxation. The transient contraction induced by Phe was inhibited. The oral administration of EEAT reduced MAP and did not alter the HR. Phenolic acids, flavonoids and indole alkaloids were identified in EEAT. In conclusions, the EEAT induced vasorelaxation through a blockade of Ca2+ channels and inhibition of the mobilization of Ca2+ of the IP3-sensivite Ca2+ stores and caused an antihypertensive effect.