Isolated Rat Aorta Research Articles

Endothelial TRP channels and cannabinoid receptors are involved in affinin-induced vasodilation

Affinin is mainly recognized by its antinociceptive effect. Recently, our research group demonstrated that this compound produces vasodilation via activation of the gasotransmitters signaling pathways. However, the molecular targets of affinin were not identified. Considering the structural similarity of this alkamide with anandamide, we hypothesized that affinin-induced vasodilation could involve participation of TRP channels and cannabinoid receptors. In this work, by using the isolated rat aorta assay, we assessed involvement of TRP channels, the cannabinoid system, and the HNO-CGRP-TRPA1 pathway on the mechanism of action of affinin. Additionally, we measured NO and H2S levels elicited by affinin on rat aorta homogenates and carried out computer simulations of molecular interactions between affinin and the TRPA1 and TRPV1 channels and the CB1 receptor. Our results indicated that affinin induces an increase in aortic NO and H2S levels. We found evidence that the vasodilator effect induced by affinin involves activation of TRPA1 and TRPV1 channels and the CB1 and eCB receptors. In silico analyses showed that affinin is able to bind with high affinity to these molecular targets. Moreover, we also proved that affinin-induced vasodilation is partly mediated via activation of the HNO-TRPA1-CGRP pathway. Based on these results we propose a novel mechanism of action to explain the vasodilatory effect of affinin, which could be developed as an alternative drug to treat cardiovascular diseases.

Novel serotonin 5-HT2A receptor antagonists derived from 4-phenylcyclohexane-5-spiro-and 5-methyl-5-phenyl-hydantoin, for use as potential antiplatelet agents

BackgroundAntiplatelet drugs have been used in the treatment of acute coronary syndromes and for the prevention of recurrent events. Unfortunately, many patients remain resistant to the available antiplatelet treatment. Therefore, there is a clinical need to synthesize novel antiplatelet agents, which would be associated with different pathways of platelet aggregation, to develop an alternative or additional treatment for resistant patients. Recent studies have revealed that 5-HT2A receptor antagonists could constitute alternative antiplatelet therapy.MethodsBased on the structures of the conventional 5-HT2A receptor ligands, two series of compounds with 4-phenylcyclohexane-5-spiro- or 5-methyl-5-phenyl-hydantoin core linked to various arylpiperazine moieties were synthesized and their affinity for 5-HT2A receptor was assessed. Further, we evaluated their antagonistic potency at 5-HT2A receptors using isolated rat aorta and cells expressing human 5-HT2A receptors. Finally, we studied their anti-aggregation effect and compared it with ketanserin and sarpogrelate, the reference 5-HT2A receptor antagonists. Moreover, the structure–activity relationships were studied following molecular docking to the 5-HT2A receptor model.ResultsFunctional bioassays revealed some of the synthesized compounds to be moderate antagonists of 5-HT2A receptors. Among them, 13, 8-phenyl-3-(3-(4-phenylpiperazin-1-yl)propyl)-1,3-diazaspiro[4.5]decane-2,4-dione, inhibited collagen stimulated aggregation (IC50 = 27.3 μM) being more active than sarpogrelate (IC50 = 66.8 μM) and comparable with ketanserin (IC50 = 32.1 μM). Moreover, compounds 2–5, 9–11, 13, 14 inhibited 5-HT amplified, ADP- or collagen-induced aggregation.ConclusionsOur study confirmed that the 5-HT2A antagonists effectively suppress platelet aggregation and remain an interesting option for the development of novel antiplatelet agents with an alternative mechanism of action.

Lipid Emulsion Enhances Vasoconstriction Induced by Dexmedetomidine in the Isolated Endothelium-Intact Aorta.

This study aimed to examine the effect of lipid emulsion (LE) on the vasoconstriction induced by dexmedetomidine (DMT) in the isolated rat aorta and elucidate the associated cellular mechanism. The effect of LE, NW-nitro-L-arginine methyl ester (L-NAME), and methyl-β-cyclodextrin (MβCD) on the DMT-induced contraction was examined. We investigated the effect of LE on the DMT-induced cyclic guanosine monophosphate (cGMP) formation and DMT concentration. The effect of DMT, LE, 4-Amino-3-(4-chlorophenyl)-1-(t-butyl)-1H-pyrazolo[3,4-d]pyrimidine,4-Amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2), and rauwolscine on the phosphorylation of endothelial nitric oxide synthase (eNOS), caveolin-1, and Src kinase was examined in the human umbilical vein endothelial cells. L-NAME, MβCD, and LE (1%, standardized mean difference (SMD): 2.517) increased the DMT-induced contraction in the endothelium-intact rat aorta. LE (1%) decreased the DMT (10−6 M) concentration (SMD: −6.795) and DMT-induced cGMP formation (SMD: −2.132). LE (1%) reversed the DMT-induced eNOS (Ser1177 and Thr496) phosphorylation. PP2 inhibited caveolin-1 and eNOS phosphorylation induced by DMT. DMT increased the Src kinase phosphorylation. Thus, LE (1%) enhanced the DMT-induced contraction by inhibition of NO synthesis, which may be caused by the decreased DMT concentration. DMT-induced NO synthesis may be caused by the increased eNOS (Ser1177) phosphorylation and decreased eNOS (Thr495) phosphorylation potentially mediated by Src kinase-induced caveolin-1 phosphorylation.

Effects of Essential Oils and Some Constituents from Ingredients of Anti-Cellulite Herbal Compress on 3T3-L1 Adipocytes and Rat Aortae.

Cellulite is associated with a complex array of adipocytes under the skin and vascular system. A herbal compress that was previously developed was proven to have an anti-cellulite effect in healthy volunteers within 2 weeks of treatment. However, its mechanism and ingredients responsible for reducing cellulite were not known. The purpose of this study was to investigate the activity of eight essential oils in, and two water extracts from, the ingredients of the herbal compress together with nine monoterpenoid constituents on the 3T3-L1 adipocytes. The vasodilatory effect on rat aortae was also studied. The adipocytes were induced by dexamethasone, 3-isobutyl-1-methylxanthine and insulin. At all concentrations tested, all essential oils, water extracts and their monoterpenoid constituents significantly inhibited lipid accumulation activity (p < 0.05) and decreased the amount of triglycerides when compared to untreated cells (p < 0.01). In addition, our results showed that the mixed oil distilled from the herbal compress mixed ingredients could relax the isolated rat aorta (EC50 = 14.74 ± 2.65 µg/mL). In conclusion, all essential oils, extracts and chemical constituents tested showed effects on adipogenesis inhibition and lipolysis induction on the cultured adipocytes with the mixed oil demonstrating vasorelaxation activity, all of which might be the mechanisms of the anti-cellulite effects of the herbal compress.

The vasodilatory effect of Apium graveolens L (celery) seed in isolated rat aorta: The roles of endothelium, calcium and potassium channels.

Abstract Objective: Apium graveolens L. (celery) seed has been used for hypertension treatment. To provide a pharmacological basis, the vasorelaxant effect of celery seed extract was investigated in isolated rat aorta. Materials and Methods: Wistar male rats (200-250 g) were divided into 15 groups (n=7 for each group). The vasorelaxant response of different concentrations of celery seed extract (0.05, 0.1, 0.25, 0.5, 1, and 2 mg/ml) on isolated aorta precontracted with phenylephrine (PE) or KCl was evaluated by organ bath technique. The role of endothelium, extracellular calcium influx, intracellular sources of calcium, and potassium channels in vasorelaxant effect of celery seed extract was investigated. Results: The extract showed a concentration-dependent relaxation in the isolated aorta contracted with PE and KCl that was endothelium-dependent at lower concentrations. Pretreatment of aortic rings with indomethacin or L-NAME, did not affect the vasorelaxation induced by celery seed extract. The extract inhibited KCl and PE-induced contractions in cumulative calcium concentrations as well as after incubation with diltiazem in denuded aortic rings of endothelium. The relaxation induced by celery seed extract was inhibited by 4-aminopyridine. Conclusion: This relaxation was mediated by inhibiting calcium influx into vascular smooth muscle cells. Also, voltage-dependent potassium channels were involved in inducing the vasorelaxant effect of celery seed extract.

In Vivo Targeted Metabolomic Profiling of Prostanit, a Novel Anti-PAD NO-Donating Alprostadil-Based Drug.

Prostanit is a novel drug developed for the treatment of peripheral arterial diseases. It consists of a prostaglandin E1 (PGE1) moiety with two nitric oxide (NO) donor fragments, which provide a combined vasodilation effect on smooth muscles and vascular spastic reaction. Prostanit pharmacokinetics, however, remains poorly investigated. Thus, the object of this study was to investigate the pharmacokinetics of Prostanit-related and -affected metabolites in rabbit plasma using the liquid chromatography-mass spectrometry (LC-MS) approach. Besides, NO generation from Prostanit in isolated rat aorta and human smooth muscle cells was studied using the Griess method. In plasma, Prostanit was rapidly metabolized to 1,3-dinitroglycerol (1,3-DNG), PGE1, and 13,14-dihydro-15-keto-PGE1. Simultaneously, the constant growth of amino acid (proline, 4-hydroxyproline, alanine, phenylalanine, etc.), steroid (androsterone and corticosterone), and purine (adenosine, adenosine-5 monophosphate, and guanosine) levels was observed. Glycine, aspartate, cortisol, and testosterone levels were decreased. Ex vivo Prostanit induced both NO synthase-dependent and -independent NO generation. The observed pharmacokinetic properties suggested some novel beneficial activities (i.e., effect prolongation and anti-inflammation). These properties may provide a basis for future research of the effectiveness and safety of Prostanit, as well as for its characterization from a clinical perspective.

Erythrocytes Induce Endothelial Injury in Type 2 Diabetes Through Alteration of Vascular Purinergic Signaling.

It is well established that altered purinergic signaling contributes to vascular dysfunction in type 2 diabetes (T2D). Red blood cells (RBCs) serve as an important pool for circulating ATP and the release of ATP from RBCs in response to physiological stimuli is impaired in T2D. We recently demonstrated that RBCs from patients with T2D (T2D RBC) serve as key mediators of endothelial dysfunction. However, it remains unknown whether altered vascular purinergic signaling is involved in the endothelial dysfunction induced by dysfunctional RBCs in T2D. Here, we evaluated acetylcholine-induced endothelium-dependent relaxation (EDR) of isolated rat aortas after 18 h ex vivo co-incubation with human RBCs, and aortas of healthy recipient rats 4 h after in vivo transfusion with RBCs from T2D Goto-Kakizaki (GK) rats. Purinergic receptor (PR) antagonists were applied in isolated aortas to study the involvement of PRs. EDR was impaired in aortas incubated with T2D RBC but not with RBCs from healthy subjects ex vivo, and in aortas of healthy rats after transfusion with GK RBCs in vivo. The impairment in EDR by T2D RBC was attenuated by non-selective P1R and P2R antagonism, and specific A1R, P2X7R but not P2Y6R antagonism. Transfusion with GK RBCs in vivo impaired EDR in aortas of recipient rats, an effect that was attenuated by A1R, P2X7R but not P2Y6R antagonism. In conclusion, RBCs induce endothelial dysfunction in T2D via vascular A1R and P2X7R but not P2Y6R. Targeting vascular purinergic singling may serve as a potential therapy to prevent endothelial dysfunction induced by RBCs in T2D.

Linolenic acid enhances contraction induced by phenylephrine in isolated rat aorta

This study examined the effect of linolenic acid on the contraction of isolated endothelium-intact and -denuded rat aorta induced by phenylephrine and its underlying mechanism. This was conducted in the presence or absence of NW-nitro-L-arginine methyl ester (L-NAME), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), methylene blue, and calmidazolium. The effects of linolenic acid on contraction induced by calcium chloride in calcium-free Krebs solution containing 60 mM potassium chloride were also examined. Moreover, the effect of linolenic acid on the association between intracellular calcium level ([Ca2+]i) and tension induced by phenylephrine was examined. Finally, we examined the effects of linolenic acid on cGMP formation and endothelial nitric oxide synthase (eNOS) phosphorylation induced by phenylephrine. Linolenic acid (5 × 10−5 M) increased phenylephrine-induced contraction in endothelium-intact aorta (standardized mean difference [SMD] of log ED50: 2.23), whereas it decreased this contraction in endothelium-denuded aorta (SMD: 1.96). L-NAME, ODQ, methylene blue, and calmidazolium increased phenylephrine-induced contraction in endothelium-intact aorta. Linolenic acid decreased contraction induced by calcium chloride in calcium-free Krebs solution containing 60 mM potassium chloride in endothelium-denuded aorta. Linolenic acid caused an increase in [Ca2+]i (SMD at 3 × 10−7 M phenylephrine: 1.63) and calcium sensitivity induced by phenylephrine in endothelium-intact aorta. Conversely, linolenic acid decreased [Ca2+]i (SMD: 0.99) induced by phenylephrine in endothelium-denuded aorta. Linolenic acid decreased cGMP formation and eNOS phosphorylation induced by phenylephrine. These results suggest that linolenic acid increases phenylephrine-induced contraction, which is attributed to linolenic acid inhibition of endothelial NO release rather than its decrease of [Ca2+]i in vascular smooth muscle.

Vasorelaxant effect of the dichloromethane fraction from Lippia thymoides involves voltage-gated potassium channels and the suppression of intracellular calcium in rat aortae

The crude extract and fractions from the leaves and stems of Lippia thymoides Mart. & Schauer, Verbenaceae, were evaluated to determine their vasorelaxant activity on isolated rat aortae. The chromatographic profile from the crude extract and the most potent fraction was determined by HPLC-DAD. The dichloromethane fraction (LtSD) displayed the more potent vasorelaxant effect on phenylephrine-induced tonic contractions in isolated rat aortae with (EC50 = 38.5 (26.3–56.5) μg/ml) or without (EC50 = 37.9 (28.5–50.5) μg/ml) functional endothelium. LtSD-mediated vasorelaxation in endothelium-intact aortic rings was not altered in the presence of atropine, l-NAME, indomethacin, or methylene blue. Preincubation of endothelium-denuded aortic rings with CsCl, glibenclamide, or tetraethylammonium did not alter the effects of LtSD-induced relaxation, but in the presence of 4-aminopyridine, the concentration-response curve of LtSD (EC50 = 37.63 (32.88–43.06) μg/ml in the absence of blocker) shifted to the right and the EC50 value was significantly increased to 156.0 (129.5–187.8) μg/ml. In addition, preincubation with LtSD plus nifedipine inhibited phenylephrine contractions similarly to LtSD alone. These results indicated that the vasorelaxant mechanisms of LtSD were mediated via endothelium-independent pathways, probably involving the activation of KV channels and the reduction of Ca2+ influx through intracellular stores.

Modulatory effects of BPC 157 on vasomotor tone and the activation of Src-Caveolin-1-endothelial nitric oxide synthase pathway

BPC 157-activated endothelial nitric oxide synthase (eNOS) is associated with tissue repair and angiogenesis as reported in previous studies. However, how BPC 157 regulates the vasomotor tone and intracellular Src-Caveolin-1 (Cav-1)-eNOS signaling is not yet clear. The present study demonstrated a concentration-dependent vasodilation effect of BPC 157 in isolated rat aorta. Attenuation of this vasodilation effect in the absence of endothelium suggested an endothelium-dependent vasodilation effect of BPC 157. Although slightly increased vasorelaxation in aorta without endothelium was noticed at high concentration of BPC 157, there was no direct relaxation effect on three-dimensional model made of vascular smooth muscle cells. The vasodilation effect of BPC 157 was nitric oxide mediated because the addition of L-NAME or hemoglobin inhibited the vasodilation of aorta. Nitric oxide generation was induced by BPC 157 as detected by intracellular DFA-FM DA labeling which was capable of promoting the migration of vascular endothelial cells. BPC 157 enhanced the phosphorylation of Src, Cav-1 and eNOS which was abolished by pretreatment with Src inhibitor, confirming the upstream role of Src in this signal pathway. Activation of eNOS required the released binding with Cav-1 in advance. Co-immunoprecipitation analysis revealed that BPC 157 could reduce the binding between Cav-1 and eNOS. Together, the present study demonstrates that BPC 157 can modulate the vasomotor tone of an isolated aorta in a concentration- and nitric oxide-dependent manner. BPC 157 can induce nitric oxide generation likely through the activation of Src-Cav-1-eNOS pathway.

Evaluation of green tea extract and epigallocatechin gallate effects on bisphenol A-induced vascular toxicity in isolated rat aorta and cytotoxicity in human umbilical vein endothelial cells.

This study was designed to assess bisphenol A (BPA)-induced vascular toxicity, the effectiveness of green tea extract and epigallocatechin gallate (EGCG) against BPA toxicity, and possible underlying mechanisms. In isolated rat aorta, contractile and relaxant responses as well as malondialdehyde levels were evaluated. Cell viability and effects on the protein levels of apoptotic (bax, bcl2, and caspase-3), autophagic (LC3), and cell adhesion molecules were calculated using the MTT method and western blotting in human umbilical vein endothelial cells (HUVECs). BPA increased aorta MDA levels (p < .0001) and decreased vascular responses to KCl [20 and 40 mM (p < .0001), 80 mM (p < .001)], phenylephrine [10-8 , 10-6 , and 10-5 M (p < .001), 10-7 and 10-4 M (p < .0001)], and acetylcholine [10-6 M (p < .01), 10-5 and 10-4 M (p < .0001)]. In HUVECs, BPA enhanced the levels of LC3A/B, bax/bcl2 ratio, cleaved caspase-3, and vascular cell adhesion molecule-1. Green tea extract, EGCG, and vitamin E co-treatment with BPA diminished the toxic effects of BPA. These findings provide evidence that green tea extract and EGCG possess beneficial effects in preventing BPA-induced vascular toxicity through increasing the antioxidant activities and the regulation of signaling pathways.

İzole sıçan aortunda dobutaminin vazokonstriktör etkisinde beta adrenerjik reseptörler rol oynar

Purpose: Experimental evidence exists that cardiac action of dobutamine is mediated by alfa-1 and beta- adrenergic receptors. However, uncertainty remains regarding the vascular effect of dobutamine and contribution of beta-adrenergic receptors to this effect. The aim of the present study was to investigate the direct effect of dobutamine in the rat aorta and the role of beta-adrenergic receptors in this effect. Materials and methods: The isolated thoracic aortic rings were mounted in organ bath containing Krebs-Henseleit solution. After an equilibiration period, endothelial integrity was then checked by the response to acetylcholine (10 μM) in aortic rings pre-contracted with phenylephrine (1 μM). After washout, dobutamine (0.001-10 μM) was added to generate cumulative concentration–response curves (CCRCs). To investigate the role of alfa- and beta- adrenergic receptors in the dobutamine-induced vascular response, prazosin (0.0003 µM) or propranolol (1 µM) was added to the bath medium 30 min before the addition of dobutamine in some experiments.. Results: Dobutamine produced concentration-dependent contraction in the endothelium-intact isolated rat aorta. This effect was significantly inhibited by either propranolol or prazosin (p<0.05). Prazosin also significantly supressed the maximum vascular response obtained by dobutamine (p<0.05). Conclusion: The results, to the best of my knowledge, demonstrates for the first time that beta-adrenergic receptors are involved in the vasoconstrictor effect of dobutamine in the endothelium-intact rat aorta.

Comparative study of acute in vitro and short-term in vivo triiodothyronine treatments on the contractile activity of isolated rat thoracic aortas.

We aimed to characterize the participation of rapid non-genomic and delayed non-genomic/genomic or genomic mechanisms in vasoactive effects to triiodothyronine (T3), emphasizing functional analysis of the involvement of these mechanisms in the genesis of nitric oxide (NO) of endothelial or muscular origin. Influences of in vitro and in vivo T3 treatments on contractile and relaxant responsiveness of isolated rat aortas were studied. In vivo T3-treatment was 500 μg•kg–1•d–1, subcutaneous injection, for 1 (T31d) and 3 (T33d) days. In experiments with endothelium-intact aortic rings contracted with phenylephrine, increasing concentrations of T3 did not alter contractility. Likewise, in vitro T3 did not modify relaxant responses induced by acetylcholine or sodium nitroprusside (SNP) nor contractile responses elicited by phenylephrine or angiotensin II in endothelium-intact aortas. Concentration-response curves (CRCs) to acetylcholine and SNP in endothelium-intact aortic rings from T31d and T33d rats were unmodified. T33d, but not T31d, treatment diminished CRCs to phenylephrine in endothelium-intact aortic rings. CRCs to phenylephrine remained significantly depressed in both endothelium-denuded and endothelium-intact, nitric oxide synthase inhibitor-treated, aortas of T33d rats. In endothelium-denuded aortas of T33d rats, CRCs to angiotensin II, and high K+ contractures, were decreased. Thus, in vitro T3 neither modified phenylephrine-induced active tonus nor CRCs to relaxant and contractile agonists in endothelium-intact aortas, discarding rapid non-genomic actions of this hormone in smooth muscle and endothelial cells. Otherwise, T33d-treatment inhibited aortic smooth muscle capacity to contract, but not to relax, in an endothelium- and NO-independent manner. This effect may be mediated by delayed non-genomic/genomic or genomic mechanisms.

Disorders on cardiovascular parameters in rats and in human blood cells caused by Lachesis acrochorda snake venom

In Colombia, Lachesis acrochorda causes 2–3% of all snake envenomations. The accidents promote a high mortality rate (90%) due to blood and cardiovascular complications. Here, the effects of the snake venom of L. acrochorda (SVLa) were analyzed on human blood cells and on cardiovascular parameters of rats. SVLa induced blood coagulation, as measured by the prothrombin time test, but did not reduce the cell viability of neutrophils and platelets evaluated by the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction assay and by the lactate dehydrogenase (LDH) enzyme assay. In fact, SVLa increased the absorbance in tests made with platelets subjected to the MTT assay. SVLa induced platelet aggregation whose magnitude was comparable to that of the positive control adenosine diphosphate (ADP), and occurred earlier with increasing SVLa concentration. Acetylsalicylic acid (ASA, a cyclooxygenase inhibitor) or clopidogrel (an ADP receptor blocker) inhibited the aggregating effect of SVLa. Inhibition of SVLa-elicited platelet aggregation also resulted from the treatment with disodium ethylenediaminetetraacetate (Na2-EDTA; metalloproteinase inhibitor) and with 4-(2-aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF, serine protease inhibitor). In isolated right atrium of rats, SVLa increased slightly, but significantly, the magnitude of the spontaneous contractions and, in isolated rat aorta, SVLa relaxed KCl- or phenylephrine-induced contractions. In vivo, SVLa induced hypotension and bradycardia in rats, with detection of hemorrhage in pulmonary and renal tissues. Altogether, under experimental conditions, SVLa induced blood coagulation, platelet aggregation, hypotension and bradycardia. Part of the effects presented here may be explained by the presence of snake venom metalloproteinases (SVMPs) and snake venom serine proteases (SVSPs), constituents of SVLa.

Vasorelaxant Effect of Novel Nitric Oxide-Hydrogen Sulfide Donor Chalcone in Isolated Rat Aorta: Involvement of cGMP Mediated sGC and Potassium Channel Activation.

Recently, nitric oxide (NO) and hydrogen sulfide (H2S) donating moieties were extensively studied for their role in the vasculature as they are responsible for many cellular and pathophysiological functioning. The objective of the present study is to evaluate novel NO and H2S donating chalcone moieties on isolated rat aorta for vasorelaxation, and to investigate the probable mechanism of action. To extend our knowledge of vasorelaxation by NO and H2S donor drugs, here we investigated the vasorelaxing activity of novel NO and H2S donating chalcone moieties on isolated rat aorta. The mechanism of vasorelaxation by these molecules was investigated by performing in vitro cGMP mediated sGC activation assay and using Tetraethylammonium chloride (TEA) as a potassium channel blocker and Methylene blue as NO blocker. Both NO and H2S donating chalcone moieties were found to be potent vasorelaxant. The compound G4 and G5 produce the highest vasorelaxation with 3.716 and 3.789 M of pEC50, respectively. After the addition of TEA, G4 and G5 showed 2.772 and 2.796 M of pEC50, respectively. The compounds Ca1, Ca2, and D7 produced significant activation and release of cGMP mediated sGC which was 1.677, 1.769 and 1.768 M of pEC50, respectively. The vasorelaxation by NO-donating chalcones was blocked by Methylene blue but it did not show any effect on H2S donating chalcones. The vasorelaxing potency of NO-donating molecules was observed to be less affected by the addition of TEA but H2S donors showed a decrease in both efficacy and potency. The cGMP release was more in the case of NO-donating molecules. The tested compounds were found potent for relaxing vasculature of rat aorta.

Thymoquinone Protects Against Cigarette Smoke Extract‐induced Vascular Dysfunction Through Inhibition of the RhoA/Rho‐Kinase Signaling Pathway

BackgroundThere is an ever‐growing focus on the role of natural products in modulating reactive oxygen species (ROS) and RhoA/Rho kinase‐mediated vascular disease. Thymoquinone (TQ), a constituent of the volatile oil derived from Nigella sativa seeds, possesses promising antioxidant and vasodilating properties via its effect on multiple signaling pathways; however, the effect of TQ on the RhoA/Rho‐Kinase pathway remains to be investigated. The aims of the present study were to examine whether TQ protects against CSE‐induced vascular dysfunction and to identify the underlying mechanisms of TQ on CSE‐induced ED in isolated rat aorta.MethodsCigarette smoke extract (CSE)‐exposed rat aortic rings were mounted in a wire myograph and subjected to contraction and relaxation. Quantitative assessment of RhoA activation was determined using G‐LISA RhoA activation assay kit where phosphorylation of myosin light chain‐20, myosin phosphatase‐targeting subunit 1 and protein kinase CPI‐17were determined by western blot analysis in the hole tissue protein extracts.The GSH content of aortic tissues was calculated using HPLC.ResultsTQ protected against CSE‐induced impairment of acetylcholine‐induced endothelium‐dependent relaxation, and decreased CSE‐induced ROS generation and glutathione depletion. Preincubation of aortic rings for 20 min with TQ attenuated the CSE‐enhanced phenylephrine‐induced vascular tension in endothelium‐denuded rings. TQ‐pretreated rings showed a decrease in CSE‐induced RhoA activation and phosphorylation of myosin light chain‐20, myosin phosphatase‐targeting subunit 1 and protein kinase CPI‐17.ConclusionsThese data indicate that TQ inhibited ROS generation‐induced RhoA/Rho kinase pathway activation, protecting against CSE‐induced vascular dysfunction. This study provides mechanistic insight for understanding the molecular basis and efficacy of TQ on vascular disease management.

Sulfur dioxide induces vascular relaxation through PI3K/Akt/eNOS and NO/cGMP signaling pathways in rats.

Sulfur dioxide (SO2) is a common exogenous atmospheric pollutant. Studies have shown that SO2 can cause vasodilation as a gas signaling molecule, but the specific signaling pathways are not well understood. This study aimed to explore the underlying mechanism behind the effects of SO2 on vasodilation of isolated rat aorta. The results showed that when the dose of SO2 was 30 μM, the vasodilation of endothelium-intact rings was partially suppressed by LY294002 and NG-nitro-l-arginine methyl ester, and the protein levels of phosphoinositide 3-kinase (PI3K), p-Akt, and p-endothelial nitric oxide synthase (p-eNOS) were significantly increased. When the dose of SO2 was 300 μM or 1500 μM, the vasodilation of endothelium-denuded rings did not change after application of the inhibitor, but the protein levels of PI3K, p-Akt, and p-eNOS were significantly decreased, and the activity of NOS and the level of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) were significantly increased. We speculate that the mechanism of SO2-induced vasodilatation likely involved the endothelial PI3K/Akt/eNOS and NO/cGMP signal pathways. In addition, at the concentration of 1500 μM, SO2 markedly increased the level of caspase-3 and caspase-9. The results suggest that high concentrations of SO2 may cause damage to blood vessels. This study will help to further inform the etiologies of SO2-related cardiovascular disease.

Lipofundin MCT/LCT Inhibits Levcromakalim-Induced Vasodilation by Inhibiting Endothelial Nitric Oxide Release.

The goal of this study was to examine the effect of lipid emulsion on the vasodilation induced by ATP-sensitive potassium (KATP) channels in isolated rat aortae and the underlying mechanism. The effects of Intralipid, containing 100% long-chain fatty acids, and Lipofundin MCT/LCT, containing 50% long-chain fatty acids plus 50% medium-chain fatty acids, on the vasodilation induced by levcromakalim in endothelium-intact aorta with or without NW-nitro-L-arginine methyl ester (L-NAME) and in endothelium-denuded aorta were examined. The effects of L-arginine, L-NAME, glibenclamide, and Lipofundin MCT/LCT, alone or combined, on the levcromakalim-induced vasodilation were examined. Lipofundin MCT/LCT inhibited the levcromakalim-induced vasodilation of isolated endothelium-intact aortae, whereas Intralipid did not. In addition, Lipofundin MCT/LCT had no effect on the levcromakalim-induced vasodilation of endothelium-denuded rat aortae and endothelium-intact aortae with L-NAME. L-arginine and Lipofundin MCT/LCT produced more levcromakalim-induced vasodilation than Lipofundin MCT/LCT alone. Glibenclamide inhibited levcromakalim-induced vasodilation. Levcromakalim did not significantly alter endothelial nitric oxide synthase phosphorylation, whereas Lipofundin MCT/LCT decreased cyclic guanosine monophosphate. Lipofundin MCT/LCT did not significantly alter levcromakalim-induced membrane hyperpolarization. Taken together, these results suggest that Lipofundin MCT/LCT inhibits the vasodilation induced by levcromakalim by inhibiting basally released endothelial nitric oxide, which seems to occur through medium-chain fatty acids.

Morin attenuates high-fat diet induced-obesity related vascular endothelial dysfunction in Wistar albino rats

Vascular endothelial dysfunction is caused by dyslipidemia, hypertension, and deficiency of antioxidant systems. In this study, the protective effect of a flavonol, morin was investigated in high-fat diet (HFD)-induced dyslipidemia and vascular endothelium dysfunction. The dose-dependent attenuating effect of morin was tested at doses of 50 and 100 mg/kg/day in an in-vivo model of HFD-induced dyslipidemia using rats whereas vascular endothelial reactivity was assessed in isolated rat aorta using ex-vivo organ bath setup. Morin administration in HFD-induced dyslipidemic rats for three weeks, resulted in a significant decrease in the body weight, LW/BW ratio as compared to rats treated with HFD only where the increase in body weight was observed. Significant reduction in the waist, BMI and lee index was also observed after morin treatment in HFD-induced dyslipidemic rats. In the lipid profile studies, HFD group showed a significant increase in the total cholesterol, triglyceride, LDL, and VLDL levels while HDL levels were decreased significantly, whereas morin treatment reversed all these parameters which were comparable to standard diet (SD) group. In the ex-vivo isolated aorta studies, HFD-induced endothelium dysfunction was observed, whereas it was reversed in the aorta of animals treated with morin at doses of 50 and 100 mg/kg/day, comparable to SD group. Morin treatment produced dose-dependent improvement in lipid profile and vascular endothelium protection, thus rationalizing its medicinal use in dyslipidemia and cardiovascular-related endothelial disorders.

Nitric oxide-mediated inhibition of phenylephrine-induced contraction in response to hypothermia is partially modulated by endothelial Rho-kinase.

This study examined the possible upstream cellular signaling pathway associated with nitric oxide (NO)-mediated inhibition of phenylephrine-induced contraction in isolated rat aortae in response to mild hypothermia, with a particular focus on endothelial Rho-kinase. We examined the effects of mild hypothermia (33°C), wortmannin, Nω-nitro-L-arginine methyl ester (L-NAME), Y-27632, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and methylene blue, alone and combined, on phenylephrine-induced contraction in isolated rat aortae. Finally, we examined the effects of mild hypothermia, wortmannin, Y-27632 and L-NAME, alone and combined, on endothelial nitric oxide synthase (eNOS) and endothelial Rho-kinase membrane translocation induced by phenylephrine. Mild hypothermia attenuated phenylephrine-induced contraction only in endothelium-intact aortae. L-NAME, wortmannin, ODQ and methylene blue increased phenylephrine-induced contraction of endothelium-intact aortae pretreated at 33°C. Wortmannin did not significantly alter the L-NAME-induced enhancement of phenylephrine-induced maximal contraction of endothelium-intact aortae pretreated at 33°C. Wortmannin abolished the ability of Y-27632 to magnify the hypothermic inhibition of maximal phenylephrine-induced contraction. Wortmannin and L-NAME inhibited the enhancing effect of mild hypothermia on phenylephrine-induced eNOS phosphorylation. Y-27632 and L-NAME attenuated the enhancing effect of hypothermia on phenylephrine-induced endothelial Rho-kinase membrane translocation. The results suggest that hypothermia-induced, NO-dependent inhibition of phenylephrine-induced contraction is mediated by phosphoinositide 3-kinase and inhibited by endothelial Rho-kinase activation.