Relaxation Of Rat Aorta Research Articles

Chemical Characterization of Phoenix dactylifera L. Seeds and their Beneficial Effects on the Vascular Response in Hypertensive Rats.

Although Phoenix dactylifera dates are traditionally consumed for their health benefits, no research has been done on the vascular response in hypertensive animals. This study evaluated the vascular relaxation of hydroalcoholic extracts from seeds of three varieties of P. dactylifera; Sukkari seed (SS), Ajwa seed (AS), and Mabroom seed (MS) on L-NAME-induced hypertension and spontaneously hypertensive rats (SHR). Results showed that all extracts (10µg/mL) caused relaxations higher than 60% in the aortic rings precontracted with 10- 6 M phenylephrine in normotensive rats, the SS extract was the most potent. Endothelial nitric oxide (NO) pathway is involved as significantly reduced vascular relaxation in denuded-endothelium rat aorta and with an inhibitor (10- 4 M L-Nω-Nitro arginine methyl ester; L-NAME) of endothelial nitric oxide synthase (eNOS). Confocal microscopy confirmed that 10µg/mL SS extract increases NO generation as detected by DAF-FM fluorescence in intact aortic rings. Consistent with these findings, vascular relaxation in intact aortic rings at 10µg/mL SS extract was significantly decreased in L-NAME-induced hypertensive rats (endothelial dysfunction model), but not in SHR. In both hypertensive models, the denuded endothelium blunted the vascular relaxation. In conclusion, the hydroalcoholic extract of the seed of P. dactylifera (Sukkari, Ajwa and Mabroom varieties) presents a potent endothelium-dependent vascular relaxation, via NO, in normotensive rats as well as in two different models of hypertension. This effect could be mediated by the presence of phenolic compounds identified by UHPLC-ESI-MS/MS, such as protocatechuic acid, and caftaric acid.

A new oxime synthesized from Senecio nutans SCh. Bip (chachacoma) reduces calcium influx in the vascular contractile response in rat aorta.

Senecio nutans Sch. Bip is an endemic plant commonly employed in the Andes culture to counteract the effects of mountain sickness, and its bioactive molecules could provide new drugs for treating hypertension. The purpose was to determine whether the vascular response of the plant bioactive molecules, such as (5-acetyl-6-hydroxy-2-isopropenyl-2,3-dihydrobenzofurane; Sn-I), could be improved by a simple structural modification to synthesize oximes (Ox-Sn-I). We characterized both compounds using IR and NMR spectroscopy and Heteronuclear Multiple Quantum Coherence (HMQC). We investigated vascular relaxation mechanisms in response to Sn-I and Ox-Sn-I using rat aorta and vascular smooth muscle cells (A7r5) as experimental models. Preincubation of aortic rings with Sn-I (10-5 M) significantly (p < 0.001) decreased the contractile effect in response to phenylephrine (PE) and potassium chloride (KCl). The sensitivity (EC50) to PE significantly (p < 0.01) decreased in the presence of Sn-I (10-5 M), but not with Ox-Sn-I. Sn-I significantly (p < 0.001) reduced the PE-induced contraction under calcium-free conditions. When A7r5 cells were preincubated with Sn-I and Ox-Sn-I (10-5 M), both compounds blunted the increase in intracellular Ca2+ induced by KCl. 2,3-Dihydrobenzofurane derived from S. nutans (Sn-I) reduces the contractile response probably by blocking Ca2+ entry through voltage-gated Ca2+ channels (VGCC) in vascular smooth cells. This effect also causes relaxation in rat aorta mediated by reduction of intracellular Ca2+ concentration, rather than an increase of NO generation in endothelial vascular cells.

Varied effects of tobacco smoke and e-cigarette vapor suggest that nicotine does not affect endothelium-dependent relaxation and nitric oxide signaling

Chronic smoking causes dysfunction of vascular endothelial cells, evident as a reduction of flow-mediated dilation in smokers, but the role of nicotine is still controversial. Given the increasing use of e-cigarettes and other nicotine products, it appears essential to clarify this issue. We studied extracts from cigarette smoke (CSE) and vapor from e-cigarettes (EVE) and heated tobacco (HTE) for their effects on vascular relaxation, endothelial nitric oxide signaling, and the activity of soluble guanylyl cyclase. The average nicotine concentrations of CSE, EVE, and HTE were 164, 800, and 85 µM, respectively. At a dilution of 1:3, CSE almost entirely inhibited the relaxation of rat aortas and porcine coronary arteries to acetylcholine and bradykinin, respectively, while undiluted EVE, with a 15-fold higher nicotine concentration, had no significant effect. With about 50% inhibition at 1:2 dilution, the effect of HTE was between CSE and EVE. Neither extract affected endothelium-independent relaxation to an NO donor. At the dilutions tested, CSE was not toxic to cultured endothelial cells but, in contrast to EVE, impaired NO signaling and inhibited NO stimulation of soluble guanylyl cyclase. Our results demonstrate that nicotine does not mediate the impaired endothelium-dependent vascular relaxation caused by smoking.

Chemical Fingerprinting, Aorta Endothelium Relaxation Effect, and Enzymatic Inhibition of Canelo (Drimys winteri J. R. Forst. &amp; G. Forst, (D.C) A. Gray, Family Winteraceae) Fruits

Drimys winteri J.R. Forst. &amp; G. Forst (D.C) G. Gray, var. chilensis (canelo) is an endemic tree from Chile. Since pre-Columbian times, it has produced a fruit known as the canelo pepper, (pimienta de canelo) or Foye pepper, which can be used as a spice. The chemical and biological analysis of canelo fruits is reported for the first time in this study, that is, its phenolic fingerprinting by UHPLC-PDA- Q-orbitrap MS, the antioxidant activity, the enzymatic inhibitory activity, and its relaxation effects on rat aorta. The proximal composition and the mineral content (Ca: 1.45 ± 0.03 mg/100 g; Mg: 7.72 ± 0.03 mg/100 g; Fe: 4.54 ± 0.21 mg/100 g; Zn: 2.99 ± 0.02 mg/100 g; Mn: 1.08 ± 0.03 mg/100 g; Cu: 0.82 ± 0.02 mg/100 g; K: 53.03 ± 0.20 mg/100 g; Na: 0.087 ± 0.00 mg/100 g) are also reported. The canelo fruits showed a total phenolic content of 57.33 ± 0.82 mg GAE/g dry weight. In addition, the total flavonoid content was 38.42 ± 1.32 mg equivalent of QE/g dry weight. The antioxidant activity was evaluated by employing DPPH and ABTS methods (IC50 of 6.65 ± 0.5 and 9.5 ± 0.05 μg/mL, respectively), ORAC (25.33 ± 1.2 μmol Trolox/g dry plant) and FRAP (45.56 ± 1.32 μmol Trolox/g dry plant). The enzymatic inhibition of acetylcholinesterase, butyrylcholinesterase, and tyrosinase (IC50: 1.94 ± 0.07, 2.73 ± 0.05, and 9.92 ± 0.05 µg extract/mL, respectively) is also reported. Canelo extract led to an 89% relaxation of rat aorta. Our results confirm that D. winteri fruits are a rich source of secondary metabolites and can inhibit enzymes associated with neurodegenerative diseases; the results also suggest that canelo may induce a potentially hypotensive effect in rat aorta. The study demonstrates the medicinal properties of canelo fruit and spice.

A subfraction obtained from the venom of the tarantula Poecilotheria regalis contains inhibitor cystine knot peptides and induces relaxation of rat aorta by inhibiting L-type voltage-gated calcium channels.

Venoms from tarantulas contain low molecular weight vasodilatory compounds whose biological action is conceived as part of the envenomation strategy due to its propagative effects. However, some properties of venom-induced vasodilation do not match those described by such compounds, suggesting that other toxins may cooperate with these ones to produce the observed biological effect. Owing to the distribution and function of voltage-gated ion channels in blood vessels, disulfide-rich peptides isolated from venoms of tarantulas could be conceived into potential vasodilatory compounds. However, only two peptides isolated from spider venoms have been investigated so far. This study describes for the first time a subfraction containing inhibitor cystine knot peptides, PrFr-I, obtained from the venom of the tarantula Poecilotheria regalis. This subfraction induced sustained vasodilation in rat aortic rings independent of vascular endothelium and endothelial ion channels. Furthermore, PrFr-I decreased calcium-induced contraction of rat aortic segments and reduced extracellular calcium influx to chromaffin cells by the blockade of L-type voltage-gated calcium channels. This mechanism was unrelated to the activation of potassium channels from vascular smooth muscle, since vasodilation was not affected in the presence of TEA, and PrFr-I did not modify the conductance of the voltage-gated potassium channel Kv10.1. This work proposes a new envenomating function of peptides from venoms of tarantulas, and establishes a new mechanism for venom-induced vasodilation.

UHPLC-MS Phenolic Fingerprinting, Aorta Endothelium Relaxation Effect, Antioxidant, and Enzyme Inhibition Activities of Azara dentata Ruiz & Pav Berries.

Azara dentata Ruiz & Pav. is a small Chilean native plant from Patagonia, a producer of small white reddish berries. For the first time, the proximal analysis of the fruits, phenolic fingerprinting, the antioxidant activity, and the enzymatic inhibition and relaxation effects in rat aorta induced by the ethanolic extract of these fruits were investigated. The proximal composition and the mineral (Ca: 2434 ± 40 mg/kg; Mg: 702 ± 13 mg/kg; Fe: 117.1 ± 1.6 mg/kg; Zn: 16.1 ± 0.4 mg/kg) and heavy metal (As: 121 ± 11 µg/kg; Cd: 152 ± 5 µg/kg; Hg: 7.7 ± 1.3 µg/kg; Pb 294 ± 4 µg/kg) contents were analyzed. Anthocyanins, flavonoids, phenolic acids, and coumarins were identified using UHPLC-PDA-QTOF-MS. The ethanolic extracts showed a total phenolic content of 23.50 ± 0.93 mg GAE/g extract. In addition, the antioxidant activity was assessed using both DPPH and TEAC (28.64 ± 1.87 and 34.72 ± 2.33 mg Trolox/g of dry fruit, respectively), FRAP (25.32 ± 0.23 mg Trolox equivalent/g dry fruit), and ORAC (64.95 ± 1.23 mg Trolox equivalents/g dry fruit). The inhibition of enzymatic activities (acetylcholinesterase IC50: 2.87 + 0.23 µg extract/mL, butyrylcholinesterase IC50: 6.73 + 0.07 µg extract/mL, amylase IC50: 5.6 ± 0.0 µg extract/mL, lipase IC50: 30.8 ± 0.0 µg extract/mL, and tyrosinase IC50: 9.25 ± 0.15 µg extract/mL) was also assessed. The extract showed 50-60% relaxation in rat aorta (intact), mediated thorough the release of endothelial nitric oxide. Our results suggest that A. dentata is a good source of compounds with the capacity to inhibit important enzymes, can be hypotensive, and can thus have good potentiality as supplements in the amelioration of neurodegenerative diseases and could also have potential to be used to develop new functional foods. The study highlights the benefits of these neglected small fruits and could boost their consumption.

The effects of bisphenols on the cardiovascular system ex vivo and in vivo

The human population is regularly exposed to bisphenols. The first compound of this class, bisphenol A, is burdened by numerous reports of its potential toxicity and has been hence replaced by its analogues, so-called next generation bisphenols. Their widespread use has made them pervasive throughout the environment. These endocrine disrupting chemicals can affect the cardiovascular system, and hence the aim of this study was to test 14 bisphenols (A, AF, AP, B, BP, C, E, F, G, M, P, PH, S and Z), and compare their effects in vitro (human and rat cell lines), ex vivo (isolated rat aorta) and in vivo (Wistar Han rats, acutely or chronically exposed to low environmental and high toxic doses). The majority of the tested bisphenols relaxed rat aorta, but their potency varied markedly. The most potent compound, bisphenol AF, had an EC50 of 57 μM. The mechanism of action was likely based on the inhibition of calcium influx via L-type calcium channels. The cytotoxicity of bisphenols towards 4 human and rat cell lines (H9c2, A-10, MCF7/S0.5 and MCF7/182R-6) showed variable potencies ranging from units of micromolar to millimolar concentrations. Based on these data, an effect on arterial blood pressure and possible cardiotoxicity was expected. Contrarily, the in vivo acute effects of three doses (0.005, 0.05 and 2.5 mg/kg) of bisphenol AF and 3 other analogues (A, S and F) on the cardiovascular system were rather biologically negligible. The most potent bisphenol, AF, was also administered chronically at a dose of 2.5 mg/kg for 4 weeks to rats, but had no impact on arterial blood pressure. Our results showed that bisphenols can relax vascular smooth muscles, but the effective concentrations are too high to produce clear cardiovascular effects in relation to common biological exposure as was confirmed with the most potent bisphenol AF.

Study on the Mechanism of Mesaconitine-Induced Hepatotoxicity in Rats Based on Metabonomics and Toxicology Network.

Mesaconitine (MA), one of the main diterpenoid alkaloids in Aconitum, has a variety of pharmacological effects, such as analgesia, anti-inflammation and relaxation of rat aorta. However, MA is a highly toxic ingredient. At present, studies on its toxicity are mainly focused on the heart and central nervous system, and there are few reports on the hepatotoxic mechanism of MA. Therefore, we evaluated the effects of MA administration on liver. SD rats were randomly divided into a normal saline (NS) group, a low-dose MA group (0.8 mg/kg/day) and a high-dose MA group (1.2 mg/kg/day). After 6 days of administration, the toxicity of MA on the liver was observed. Metabolomic and network toxicology methods were combined to explore the effect of MA on the liver of SD rats and the mechanism of hepatotoxicity in this study. Through metabonomics study, the differential metabolites of MA, such as L-phenylalanine, retinyl ester, L-proline and 5-hydroxyindole acetaldehyde, were obtained, which involved amino acid metabolism, vitamin metabolism, glucose metabolism and lipid metabolism. Based on network toxicological analysis, MA can affect HIF-1 signal pathway, MAPK signal pathway, PI3K-Akt signal pathway and FoxO signal pathway by regulating ALB, AKT1, CASP3, IL2 and other targets. Western blot results showed that protein expression of HMOX1, IL2 and caspase-3 in liver significantly increased after MA administration (p < 0.05). Combined with the results of metabonomics and network toxicology, it is suggested that MA may induce hepatotoxicity by activating oxidative stress, initiating inflammatory reaction and inducing apoptosis.

Novel Oxime Synthesized from a Natural Product of Senecio nutans SCh. Bip. (Asteraceae) Enhances Vascular Relaxation in Rats by an Endothelium-Independent Mechanism.

Senecio nutans Sch. Bip. and its constituents are reported to have antihypertensive effects. We isolated metabolite–1, a natural compound from S. nutans (4-hydroxy-3-(isopenten-2-yl)-acetophenone), and synthesized novel oxime – 1 (4-hydroxy-3-(isopenten-2-yl)-acetophenoxime) to evaluate their effect on vascular reactivity. Compounds were purified (metabolite–1) or synthetized (oxime–1) and characterized using IR and NMR spectroscopy and Heteronuclear Multiple Quantum Coherence (HMQC). Using pharmacological agents such as phenylephrine (PE) and KCl (enhancing contraction), acetylcholine (ACh), L-NAME (nitric oxide (NO) and endothelial function), Bay K8644-induced CaV1.2 channel (calcium channel modulator), and isolated aortic rings in an organ bath setup, the possible mechanisms of vascular action were determined. Pre-incubation of aortic rings with 10−5 M oxime–1 significantly (p < 0.001) decreased the contractile response to 30 mM KCl. EC50 to KCl significantly (p < 0.01) increased in the presence of oxime–1 (37.72 ± 2.10 mM) compared to that obtained under control conditions (22.37 ± 1.40 mM). Oxime–1 significantly reduced (p < 0.001) the contractile response to different concentrations of PE (10−7 to 10−5 M) by a mechanism that decreases Cav1.2-mediated Ca2+ influx from the extracellular space and reduces Ca2+ release from intracellular stores. At a submaximal concentration (10−5 M), oxime–1 caused a significant relaxation in rat aorta even without vascular endothelium or after pre-incubate the tissue with L-NAME. Oxime–1 decreases the contractile response to PE by blunting the release of Ca2+ from intracellular stores and blocking of Ca2+ influx by channels. Metabolite–1 reduces the contractile response to KCl, apparently by reducing the plasma membrane depolarization and Ca2+ influx from the extracellular space. These acetophenone derivates from S. nutans (metabolite–1 and oxime–1) cause vasorelaxation through pathways involving an increase of the endothelial NO generation or a higher bioavailability, further highlighting that structural modification of naturally occurring metabolites can enhance their intended pharmacological functions.

Hydroxychloroquine induces endothelium-dependent and endothelium-independent relaxation of rat aorta.

Hydroxychloroquine (HCQ) is an antimalarial that is widely used in the management of rheumatoid arthritis and other autoimmune diseases. In this study, we aimed to examine the vascular effects of HCQ on rat aorta (RA). The RA rings were suspended in isolated organ baths and tension was recorded isometrically. HCQ-induced relaxations were tested in the presence of the nitric oxide synthase inhibitor, nitro-L-arginine methyl ester (L-NAME, 100 mM); the cyclooxygenase enzyme inhibitor, indomethacin (10 mM); the calcium (Ca2+) ion channel blocker, nilvadipine (10 μM); and the K+ ion channel inhibitors, tetraethylammonium (1 mM), glibenclamide (10 mM), 4-aminopyridine (1 mM), and barium chloride (30 mM). The effect of HCQ on Ca2+ channels was examined using Ca2+-free Krebs solution, and adding calcium chloride (CaCl2 , 10-5- 10-2 M) cumulatively to baths incubated with HCQ. Removing the endothelium resulted in less relaxation of RA rings compared to endothelium-intact rings (p < 0.05). The effect of endothelium was supported by using L-NAME where HCQ produced-vasorelaxation was decreased (p < 0.05). The contraction of vascular rings was inhibited to a significant degree following the addition of CaCl2 , PE, or KCl on HCQ-incubated RA rings (p < 0.05). The incubation of the RA rings with the Ca2+ channel blocker, the K+ channel blockers, and the COX inhibitor, indomethacin did not significantly affect vascular relaxation induced by HCQ. HCQ produced relaxation of RA rings. The relaxation mechanism differs according to the concentration of HCQ. At con-centrations of 10-6 and 10-5 M, the relaxation is endothelium-dependent and mediated by NO. We strongly suggest that Ca2+ channel inhibition is involved at concentrations of 10-5 and 10-4 M, as well as NO.

High dilutions of homeopathic remedies induce relaxation of rat aorta precontracted with Noradrenalin

BACKGROUND&#x0D; Homeopathic potencies have been reported to produce alteration of contraction in isolated rat ileum in an organ bath. Potentized homeopathic drugs like Lycopus V and Aurum met are used for the treatment of hypertension. &#x0D; AIM&#x0D; The purpose of this study is to see whether Lycopus V 30 CH and Aurum met 30 CH could produce relaxation of isolated rat aorta in the organ bath.&#x0D; METHODS&#x0D; The aorta of rats were dissected out, placed in Krebs-Henseleit solution, cleared of connective tissue and endothelium and cut into 2-2.5 mm long rings. The rings were fixed in organ baths with the upper end connected by a string to an isometric transducer which was finally attached through a data acquisitation equipment to a computer. Aurum met 30 CH Lycopus V 30 CH, and their medium 90% ethanol were added separately to the bathing fluid containing the aorta rings which were precontracted with noradrenalin (NA).&#x0D; RESULTS&#x0D; Both the drugs produced significant relaxation of the aorta (p

Punicalagin Attenuates Disturbed Flow-Induced Vascular Dysfunction by Inhibiting Force-Specific Activation of Smad1/5.

BackgroundPathophysiological vascular remodeling in response to disturbed flow with low and oscillatory shear stress (OSS) plays important roles in atherosclerosis progression. Pomegranate extraction (PE) was reported having anti-atherogenic effects. However, whether it can exert a beneficial effect against disturbed flow-induced pathophysiological vascular remodeling to inhibit atherosclerosis remains unclear. The present study aims at investigating the anti-atherogenic effects of pomegranate peel polyphenols (PPP) extraction and its purified compound punicalagin (PU), as well as their protective effects on disturbed flow-induced vascular dysfunction and their underlying molecular mechanisms.MethodsThe anti-atherogenic effects of PPP/PU were examined on low-density lipoprotein receptor knockout mice fed with a high fat diet. The vaso-protective effects of PPP/PU were examined in rat aortas using myograph assay. A combination of in vivo experiments on rats and in vitro flow system with human endothelial cells (ECs) was used to investigate the pharmacological actions of PPP/PU on EC dysfunction induced by disturbed flow. In addition, the effects of PPP/PU on vascular smooth muscle cell (VSMC) dysfunction were also examined.ResultsPU is the effective component in PPP against atherosclerosis. PPP/PU evoked endothelium-dependent relaxation in rat aortas. PPP/PU inhibited the activation of Smad1/5 in the EC layers at post-stenotic regions of rat aortas exposed to disturbed flow with OSS. PPP/PU suppressed OSS-induced expression of cell cycle regulatory and pro-inflammatory genes in ECs. Moreover, PPP/PU inhibited inflammation-induced VSMC dysfunction.ConclusionPPP/PU protect against OSS-induced vascular remodeling through inhibiting force-specific activation of Smad1/5 in ECs and this mechanism contributes to their anti-atherogenic effects.

Effects of sitagliptin on ß-adrenoceptor mediated relaxation in streptozotocin-diabetic rat aorta

Background/aim Dipeptidyl peptidase-4 (DPP4) inhibitors, a class of oral antidiabetic drugs, have been shown to be protective on the vascular system because of their antiinflammatory, antiatherosclerotic, and vasodilatory effects. ß 2-adrenoceptors (ß 2-ARs) mediate the vasorelaxation in the aorta. However, ß 3-adrenoceptor-mediated relaxation has not been studied in diabetic aorta yet. Thus, we aimed to study the effect of sitagliptin treatment on ß 2- and ß3-adrenoceptor-mediated relaxations in the diabetic rat aorta.Materials and methods Eight-week old Sprague Dawley rats were divided into three groups: control, diabetic, sitagliptin treated diabetic. Diabetes was induced by injection of streptozotocin (35 or 40 mg/kg, intraperitoneally). After 10 weeks of diabetes, some of the diabetic rats were treated with sitagliptin (orally, 10mg/kg/day). ß2- and ß 3-AR-mediated relaxation responses were evaluated by using isoprenaline and CL 316,243, respectively. ß3-AR-mediated relaxation experiments were repeated in presence of L-NAME. Western blotting and immunohistochemistry were performed to determine the abundance of ß3-adrenoceptor and endothelial nitric oxide synthase (eNOS).Results The isoprenaline-mediated relaxation response was impaired in the diabetic group and sitagliptin treatment did not improve it. There was no significant change in CL316,243 mediated-relaxation or protein expression of ß 3-ARs among the groups. However, the ratio of phosphorylated eNOS/NOS protein was increased markedly in the sitagliptin treated group, which points the stimulating effect of this drug towards the eNOS pathway. Conclusion Our results indicate that sitagliptin treatment does not alter ß- AR-mediated relaxation in streptozotocin-diabetic rat aorta; however, it significantly stimulates the eNOS pathway. Future studies are needed to clarify the relationship between the eNOS pathway and DPP-4 inhibition.

C-type natriuretic peptide-induced relaxation through cGMP-dependent protein kinase and SERCA activation is impaired in two kidney-one clip rat aorta

AimsHypertension underlies endothelial dysfunction, and activation of vasorelaxation signaling with low dependence on nitric oxide (NO) represents a good alternative for vascular modulation. C-type natriuretic peptide (CNP) causes relaxation by increasing cyclic guanosine 3′,5′-monophosphate (cGMP) or Gi-protein activation through its natriuretic peptide receptor-B or -C, respectively. We have hypothesized that CNP could exerts its effects and could overcome endothelial dysfunction in two kidney-one clip (2K-1C) hypertensive rat aorta. Here, we investigate the intracellular signaling involved in CNP effects in hypertension. Materials and methodsThe 2K-1C hypertension was induced in male Wistar rats (200 g). CNP-induced vascular relaxation and cGMP production were investigated in rat thoracic aortas. The natriuretic peptide receptor-B and -C localization was evaluated by immunofluorescence. Calcium mobilization was assessed in endothelial cells from rat aortas. Key findingsCNP induced similar relaxation in normotensive and 2K-1C hypertensive rat aortas, which increased after endothelium removal. CNP-induced relaxation involved natriuretic peptide receptor-B and -C activation in 2K-1C rats. Nitric oxide synthase (NOS) and soluble guanylyl cyclase (sGC) counter-regulated CNP-particulate GC (pGC) activation in aortas. CNP reduced endothelial calcium and increased cGMP production, which was lower in 2K-1C. CNP-induced cGMP-dependent protein kinase (PKG) and sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) activation was impaired in 2K-1C rat aorta. SignificanceOur results indicated CNP triggered relaxation through its natriuretic peptide receptor-B and -C in 2K-1C rat aortas, and that CNP-induced relaxation overcomes endothelial dysfunction in hypertension. In addition, NOS and sGC activities counter-regulate CNP-pGC activation to induce vascular relaxation.

Effect of Diterpene Manool on the Arterial Blood Pressure and Vascular Reactivity in Normotensive and Hypertensive Rats.

ResumoFundamento:Diversos estudos têm mostrado que as classes de diterpenos exercem efeito significativo no sistema cardiovascular. Os diterpenos, em particular, estão entre os principais compostos associados às propriedades cardiovasculares, como a propriedade vasorrelaxante, inotrópica, diurética e a atividade hipotensora. Embora o mecanismo de vasorrelaxamento do manool seja visível, seu efeito sobre a pressão arterial (PA) ainda é desconhecido.Objetivo:Avaliar o efeito hipotensor in vivo do manool e verificar o efeito de vasorrelaxamento ex vivo em anéis aórticos de ratos.Métodos:Os animais foram divididos aleatoriamente em dois grupos: normotensos e hipertensos. O grupo normotenso foi submetido à cirurgia sham e adotou-se o modelo 2R1C para o grupo hipertenso. Realizou-se monitoramento invasivo da PA para testes com manool em diferentes doses (10, 20 e 40 mg/kg). Foram obtidas curvas de concentração-resposta para o manool nos anéis aórticos, com endotélio pré-contraído com fenilefrina (Phe) após incubação com Nω-nitro-L-arginina metil éster (L-NAME) ou oxadiazolo[4,3-a]quinoxalina-1-ona (ODQ). Os níveis plasmáticos de óxido nítrico (NOx) foram medidos por ensaio de quimioluminescência.Resultados:Após a administração de manool, a PA se reduziu nos grupos normotenso e hipertenso, e esse efeito foi inibido pelo L-NAME em animais hipertensos apenas na dose de 10 mg/kg. O manool ex vivo promoveu vasorrelaxamento, inibido pela incubação de L-NAME e ODQ ou remoção do endotélio. Os níveis plasmáticos de NOx aumentaram no grupo hipertenso após a administração de manool. O manool induz o relaxamento vascular dependente do endotélio na aorta de ratos, mediado pela via de sinalização NO/cGMP e redução da PA, e também pelo aumento plasmático de NOx. Esses efeitos combinados podem estar envolvidos na modulação da resistência periférica, contribuindo para o efeito anti-hipertensivo do diterpeno.Conclusão:Esses efeitos em conjunto podem estar envolvidos na modulação da resistência periférica, contribuindo para o efeito anti-hipertensivo do diterpeno.

The hypertensive effect of sorafenib is abolished by sildenafil

BackgroundContrasting to the well documented tyrosine kinase inhibitor (TKI)-induced hypertension, little is known on their intrinsic vasomotor effects. We investigated the vasomotor effects of sorafenib, a widely used multikinase inhibitor in the treatment of hepatocellular and renal cell carcinoma and tested the hypothesis that sildenafil, a phosphodiesterase-5 (PDE-5) inhibitor, could represent a pharmacological strategy for the treatment of TKI-induced hypertension.MethodsConcentration-response curves of sorafenib were constructed in endothelium-intact or denuded precontracted rat aorta, in the presence or absence of several inhibitors. Acute intravenous effects of sorafenib on arterial blood pressure were also investigated in anaesthetized rats. Finally, rats were chronically treated with sorafenib during 4 weeks in the presence and absence of sildenafil.ResultsIn endothelium intact aortic ring, sorafenib induced a potent concentration-dependent relaxation of precontracted rat aorta. Removal of the endothelium shifted the concentration-response curve of sorafenib to the right and significantly reduced its maximal effects, demonstrating that sorafenib-induced vasorelaxation is endothelium-dependent and endothelium-independent. Inhibition of the different pathways implicated in the endothelium-dependent and independent vasorelaxation revealed that the endothelium-dependent effects of sorafenib result mainly from the activation of prostaglandin and the nitric oxide (NO) pathways. The endothelium-independent vasodilatory effects of sorafenib may result mainly from the activation of Na/K-ATPase and soluble guanylate cyclase. These vasodilatory effects observed in vitro were confirmed by the decrease in arterial blood pressure observed during acute administrations of sorafenib in anesthetized rats. Finally, and most importantly, we report here for the first time that chronic administration of sorafenib in rats induced an increase in SBP that was abolished by sildenafil.ConclusionThe multikinase inhibitor sorafenib induced in vitro vasorelaxation of large conductance artery, primary by activating soluble guanylate cyclase. Its chronic administration led to arterial blood hypertension that was counteracted by a PDE-5 inhibitor, sildenafil. Our results suggest that targeting the cGMP pathway including NO signalling might be an interesting pharmacological strategy for the treatment of TKI-induced hypertension.

Activation of ATM/Akt/CREB/eNOS Signaling Axis by Aphidicolin Increases NO Production and Vessel Relaxation in Endothelial Cells and Rat Aortas.

Although DNA damage responses (DDRs) are reported to be involved in nitric oxide (NO) production in response to genotoxic stresses, the precise mechanism of DDR-mediated NO production has not been fully understood. Using a genotoxic agent aphidicolin, we investigated how DDRs regulate NO production in bovine aortic endothelial cells. Prolonged (over 24 h) treatment with aphidicolin increased NO production and endothelial NO synthase (eNOS) protein expression, which was accompanied by increased eNOS dimer/monomer ratio, tetrahydrobiopterin levels, and eNOS mRNA expression. A promoter assay using 5’-serially deleted eNOS promoters revealed that Tax-responsive element site, located at −962 to −873 of the eNOS promoter, was responsible for aphidicolin-stimulated eNOS gene expression. Aphidicolin increased CREB activity and ectopic expression of dominant-negative inhibitor of CREB, A-CREB, repressed the stimulatory effects of aphidicolin on eNOS gene expression and its promoter activity. Co-treatment with LY294002 decreased the aphidicolin-stimulated increase in p-CREB-Ser133 level, eNOS expression, and NO production. Furthermore, ectopic expression of dominant-negative Akt construct attenuated aphidicolin-stimulated NO production. Aphidicolin increased p-ATM-Ser1981 and the knockdown of ATM using siRNA attenuated all stimulatory effects of aphidicolin on p-Akt-Ser473, p-CREB-Ser133, eNOS expression, and NO production. Additionally, these stimulatory effects of aphidicolin were similarly observed in human umbilical vein endothelial cells. Lastly, aphidicolin increased acetylcholine-induced vessel relaxation in rat aortas, which was accompanied by increased p-ATM-Ser1981, p-Akt-Ser473, p-CREB-Ser133, and eNOS expression. In conclusion, our results demonstrate that in response to aphidicolin, activation of ATM/Akt/CREB/eNOS signaling cascade mediates increase of NO production and vessel relaxation in endothelial cells and rat aortas.

A cell permeant phosphopeptide mimetic of Niban restores endothelial function and inhibits p38 MAPK activation after vascular injury

Vascular injury leads to membrane disruption, ATP release, and endothelial dysfunction. Increases in the phosphorylation of p38 MAPK and decreases in the phosphorylation of Niban, a protein implicated in ER stress and apoptosis, are associated with vascular injury. A cell‐permeant phospho‐peptide mimetic of Niban (NiPp) was generated. The effects of NiPp in restoring endothelial function were determined ex vivo using intact rat aortic tissue (RA) after pharmacological activation of p38 MAPK and a clinically relevant stretch injury model. Anisomycin increased p38 MAPK phosphorylation and reduced endothelial‐dependent relaxation in RA. Treatment with NiPp prevented anisomycin‐induced reduction in endothelial function and increase in p38 MAPK phosphorylation (Figure 1). NiPp treatment also restored endothelial function after subfailure overstretch injury (Figure 2). Kinome screening experiments indicated that NiPp inhibits p38 MAPK. These data demonstrate that p38 MAPK and Niban signaling have a role in endothelial function, particularly in response to injury. Niban may represent an endogenous regulator of p38 MAPK activation. NiPp may serve as an experimental tool to further elucidate p38 MAPK regulation and as a potential therapeutic for endothelial dysfunction.Support or Funding InformationThis work was supported by the National Institutes of Health grants R01HL70715‐09 to CB and R01HL105731‐01 to JC.NiPp prevented anisomycin‐induced phosphorylation of p38 MAPK and endothelial dysfunction in rat aorta (RA).RA rings were treated with anisomycin (200μM) in the absence or presence of NiPp (500μM) pretreatment and endothelial function was determined in a muscle bath. A) Representative muscle bath tracings. B) Percent relaxation induced by 0.5μM CCH. C, D) Phosphorylation of p38 MAPK in RA after treatment as determined by Western blot analysis. n=10,*p&lt;.05 in one‐way ANOVA with Tukey post‐test.Figure 1NiPp restored endothelial function and reduced p38MAPK phosphorylation in RA after subfailure stretch injury.RA was subjected to subfailure stretch and incubated in the absence or presence of NiPp (500μM) for 1 h. A) Endothelial‐dependent relaxation was determined in the muscle bath. n=5 rats; #p&lt;.05, two‐way ANOVA. B, C) Phosphorylation of p38 MAPK in RA after stretch injury and NiPp treatment as determined by Western blot analysis n= 10. *p&lt;.05, in one‐way ANOVA with Tukey post‐test.Figure 2

Влияние газотрансмиттера сероводорода на микрореологические свойства эритроцитов здоровых лиц и больных сахарным диабетом второго типа

Цель исследования: изучение влияния донора газотрансмиттера (ГТ) сероводорода (NaНS) и активатора его внутриклеточного синтеза (Lцистеина) на микрореологические характеристики эритроцитов в норме и при сахарном диабете 2-го типа (СД2). Материалы и методы. Эритроциты 16 здоровых лиц и 16 больных СД2 инкубировали с донором сероводорода гидросульфидом натрия (NaHS) в концентрации 10, 50 и 100 мкмоль и стимулятором его эндогенного синтеза Lцистеином в концентрации 10, 50 и 100 мкмоль. Блокировали АТФзависимые калиевые каналы глибенкламидом (50 мкмоль). Ингибировали растворимую гуанилатциклазу с помощью 0,5 мкмоль ODQ (1H-1,2,4-oxadiazolo4,3-a quinoxalin-l-one). Регистрировали деформируемость (ИУЭ) и агрегацию эритроцитов. Результаты. Под влиянием NaHS наблюдали дозозависимые положительные изменения микрореологии эритроцитов. Микрореологические ответы эритроцитов на NaHS были более выраженными у здоровых лиц, чем у больных СД2. Сходную картину наблюдали и при воздействии на эритроциты Lцистеином. Прединкубация с глибенкламидом не устраняла положительного влияния донора ГТ на микрореологию эритроцитов, тогда как ингибирование растворимой гуанилатциклазы с помощью ODQ полностью устраняло положительные изменения ИУЭ под действием ГТ и существенно уменьшало его влияние на агрегацию клеток. Заключение. Таким образом, сероводород как газотрансмиттер улучшает микрореологию эритроцитов. При одинаковой концентрации донора сероводорода (NaHS) и стимулятора его синтеза (Lцистеина) более выраженные сдвиги микрореологических параметров эритроцитов наблюдаются у здоровых лиц по сравнению с больными СД2. Aim: to study the effect of donor gasotransmitter (GT) hydrogen sulphide (NaHS) and the activator of its intracellular synthesis (Lcysteine) on the red blood cells (RBCs) microrheological characteristics in normal and diabetes mellitus type 2 (DM2). Materials and methods. RBCs of 16 healthy individuals and 16 patients with DM2 were incubated with hydrogen sulfide donor sodium hydrosulfide (NaHS) in concentrations of 10, 50 and 100 mol and a stimulator of its endogenous synthesis Lcysteine (10, 50 and 100 mol). ATPdependent potassium channels were blocked by glibenclamide (50 mol). Soluble guanylate cyclase was inhibited using 0.5 mol ODQ (1H-1,2,4-oxadiazolo4,3-a quinoxalin-l-one). Deformability (RBCD) and RBCs aggregation were recorded. Results. Under the influence of NaHS, dose-dependent positive changes in RBCs microrheology were observed. Cellular microrheological responses to GT donor were more pronounced in healthy individuals than in patients with DM2. A similar pattern was observed when RBCs were exposed to Lcysteine. Preincubation with glibenclamide did not eliminate the positive effect of GT donor on RBCs microrheology. Whereas inhibition of soluble guanylate cyclase with the help of ODQ completely eliminated positive changes in RBCD under the action of GT and significantly reduced its effect on aggregation. Conclusion. Thus, hydrogen sulfide as a gasotransmitter improves RBCs microrheology. With the same concentration of hydrogen sulphide donor (NaHS) and its synthesis stimulator (Lcysteine), more pronounced shifts in the microrheological parameters of erythrocytes are observed in healthy individuals as compared with DM2 patients.

Fast Isolation of Flavonoids from the Endemic Species Nolana ramosissima I.M. Johnst and Its Endothelium-Independent Relaxation Effect in Rat Aorta.

The infusion of the desertic plant Nolana ramosissima I.M. Johnst showed vascular smooth muscle relaxation in rat aorta and the presence of several phenolic compounds, which were detected by high resolution UHPLC-Orbitrap-HESI-MS. In addition, five flavonoids were rapidly isolated from a methanolic extract using high-performance counter-current chromatography (HPCCC). The N. ramosissima extract showed endothelium-independent relaxation effect in rat aorta. Sixty-one compounds were detected in the infusion, mainly glycosylated flavonoids, flavanones and several oxylipins, suggesting that a synergistic effect between the compounds in the extracts could be responsible for the relaxation activity. Vascular activity experiments were done in isolated organ bath. In rat aorta, a nitric oxide inhibitor did not prevent the relaxation effects of the extract; however, a selective guanylyl cyclase inhibitor partially blunted this effect. The compound 5,3′-dihydroxy-4′7-dimethoxyflavone presented higher relaxation effect than 100 μg/mL of N. ramosissima extract. The extract and the isolated metabolites from N. ramosissima can show relaxation effects on rat aorta by a mechanism that is independent of the endothelium.