Rat Thoracic Aorta Research Articles

Theophylline-induced endothelium-dependent vasodilation is mediated by increased nitric oxide release and phosphodiesterase inhibition in rat aorta.

This study aimed to examine the endothelial dependence of vasodilation induced by the phosphodiesterase inhibitor theophylline in isolated rat thoracic aortas and elucidate the underlying mechanism, with emphasis on endothelial nitric oxide (NO). The effects of various inhibitors and endothelial denudation on theophylline-induced vasodilation, and the effect of theophylline on vasodilation induced by NO donor sodium nitroprusside, cyclic guanosine monophosphate (cGMP) analog bromo-cGMP, and β-agonist isoproterenol in endothelium-denuded aorta were examined. The effects of theophylline and sodium nitroprusside on cGMP formation were also examined. We examined the effect of theophylline on endothelial nitric oxide synthase (eNOS) phosphorylation and intracellular calcium levels. Theophylline-induced vasodilation was greater in endothelium-intact aortas than that in endothelium-denuded aortas. The NOS inhibitor, NW-nitro-L-arginine methyl ester; non-specific guanylate cyclase (GC) inhibitor, methylene blue; and NO-sensitive GC inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a] quinoxalin-1-one inhibited theophylline-induced vasodilation in endothelium-intact aortas. Theophylline increased the vasodilation induced by sodium nitroprusside, bromo-cGMP, and isoproterenol. Theophylline increased cGMP formation in endothelium-intact aortas, and sodium nitroprusside-induced cGMP formation in endothelium-denuded aortas. Moreover, theophylline increased stimulatory eNOS (Ser1177) phosphorylation and endothelial calcium levels, but decreased the phosphorylation of inhibitory eNOS (Thr495). These results suggested that theophylline-induced endothelium-dependent vasodilation was mediated by increased endothelial NO release and phosphodiesterase inhibition.

Mechanistic study of endothelium independent vasodilation effects of wogonin

Scutellaria baicalensis Georgi, locally known as HuangQin, and commonly as Baikal or Chinese skullcap, is an important herb in Chinese traditional medicine. The flavonoids from this plant are main active substances responsible for its medicinal applications. Wogonin is one such active ingredient derived from this plant. Here, we investigated the mechanism of the vasodilation effect of wogonin on isolated rat thoracic aortas. For this study, endothelium intact and endothelium removed thoracic aortic rings were prepared from rats. Using a tension transducer, the tension of the rat thoracic aortic rings was recorded. Results showed that wogonin is able to relax the endothelium-intact aortic rings, but L-NAME, indomethacin (Indo), and methylene blue (MB) could not reduce the tension in these rings. Wogonin was also able to relax endotheliumremoved rings. However, treatment with tetraethylammonium (TEA), BaCl2, glibenclamide (Gly), 4-aminopyridine (4-AP), and verapamil (Ver) had no effect on vasodilation induced by wogonin. Using wogonin to pre-treat endothelium-removed aortic rings reduced the contraction induced by K+. Pre-treatment of endothelium-removed aortic rings with wogonin markedly reduced the contraction induced by 10-6 M PE in Ca2+-free solution. It could be concluded that L-type calcium channels and intracellular Ca2+ release is inhibited by wogonin.

The level of hydrogen sulfide and morphological changes in the aorta of rats under the influence of vitamin D under the conditions of modulation of the H2S / cystathionine-γ-lyase system

Annotation. Vitamin D and hydrogen sulfide (H2S) belong to pleitropic regulators, which are involved in the control of many cellular functions and biochemical processes, determine the adaptive potential of the cardiovascular system. The relationship between vitamin D and the H2S system is not fully investigated. The aim of the study was to evaluate the effect of the active form of vitamin D - calcitriol (1,25 (OH)2D3) on the morphological state of the thoracic aorta of rats and the level of it’s saturation with hydrogen sulfide under the conditions of the H2S / cystathionine-γ-lyase system modulation. The experiments were performed on 90 white male laboratory rats in accordance with the principles of bioethics (Strasbourg, 1986). 1,25(OH)2D3 was administered in doses of 0.1 μg/kg and 1 μg/kg for 4 weeks. Propargylglycine (50 mg/kg) and NaHS (1 mg/kg) were used to modulate the state of the H2S/cystathionine-γ-lyase system. The content of H2S was determined in the thoracic aorta and morphological changes were evaluated. Statistical calculations were performed in IBM Statistics SPSS 26, differences were evaluated in the Mann-Whitney test at the significance level of p<0.05. It was established that 1,25 (OH)2D3 in a dose of 1.0 μg/kg leads to the formation of H2S deficiency and a complex of morphological changes in the aorta, which are manifested by damage of epithelial cells and stromal elements, and the formation of calcifications. Modulation of the H2S / cystathionine-γ-lyase system is a factor that modifies the effect of high doses of 1,25 (OH)2D3 on vessels: H2S deficiency increases damage of the vascular wall, while increasing tissue H2S saturation has the opposite effect. 1,25 (OH)2D3 in a dose of 0.1 μg/kg shows the ability to increase the level of endogenous H2S and reduces the development of pathological changes in blood vessels under the conditions of long-term inhibition of the H2S / cystathionine-γ-lyase system.

Oleoylethanolamide alleviates hyperlipidaemia-mediated vascular calcification via attenuating mitochondrial DNA stress triggered autophagy-dependent ferroptosis by activating PPARα

Vascular calcification, a prevalent pathological alteration in metabolic syndromes, is tightly related with cardiometabolic risk events. Ferroptosis, a newly iron-dependent programmed cell death, induced by palmitic acid (PA), the major saturated free fatty acid in hyperlipidemia, is a vital mechanism of vascular calcification. Recent studies reported that ferroptosis is a distinctive type of cell death dependent on autophagy, with the lipotoxicity of PA on cell viability being closely linked with autophagy. Oleoylethanolamide (OEA), an endogenous bioactive mediator of lipid homeostasis, exerts vascular protection against intimal calcification, atherosclerosis; however, its beneficial effect on vascular smooth muscle cell (VSMC)-associated medial calcification has not been investigated. Our aim was to characterize the effect of OEA on vascular calcification and ferroptosis of VSMCs under hyperlipidaemia/PA exposure. In vivo, vascular calcification model was induced in rats by high-fat diet and vitamin D3 plus nicotine; in vitro, VSMCs ferroptosis was induced by PA or plus β-glycerophosphate mimicking vascular calcification. The calcium deposition in hyperlipidaemia-mediated rat thoracic aortas, the PA-induced ferroptosis and subsequent calcium deposition in VSMCs, were suppressed by OEA treatment. Additionally, CGAS-STING1-induced ferritinophagy, the main molecular mechanism of PA-triggered ferroptosis of VSMCs, was activated by mitochondrial DNA damage; however, early administration of OEA alleviated these phenomena. Intriguingly, overexpression of peroxisome proliferator activated receptor alpha (PPARα) contributed to a decrease in PA-induced ferroptosis, whereas PPARɑ knockdown inhibited the OEA-mediated anti-ferroptotic effects. Collectively, our study demonstrated that OEA serves as a prospective candidate for the prevention and treatment of vascular calcification in metabolic abnormality syndromes.

The effects of irisin on the rat thoracic aorta: a histological study.

Irisin, a polypeptide hormone that is released from skeletal muscle in response to exercise, has been found to improve endothelial functions, protect against endothelial injuries and change blood pressure, which also affected blood vessels. The aim of this study was to assess the histological changes of the rat thoracic aorta in response to irisin injection. Twenty-four rats were used. They were divided into two groups: the control group without irisin injection and the irisin-injected group subdivided into three subgroups treated with different irisin concentrations (20, 40 and 160 nM, respectively) twice a week for 4 weeks. The control group and irisin-treated subgroups consisted of 6 rats each. After 4 weeks all rats were sacrificed, and the descending thoracic aorta was treated for histological evaluation. Sections were stained with haematoxylin and eosin and orcein stains. Morphometric measurement included: intima-media thickness, number of elastic lamellae and number of smooth muscle cells' nuclei. Histological study showed that intraperitoneal injection of different concentrations of irisin (20, 40 and 160 nM) in rats increased intima-media thickness, the number of smooth muscle cell's nuclei and the number of elastic lamellae in media layer of the thoracic aorta in a dose-dependent manner. Irisin significantly affected the morphology of the wall of the rat thoracic aorta indicating a role of irisin in influencing the growth factors of the thoracic aorta walls and activating smooth muscle cells in the thoracic aorta layers.

Fourier Transform Infrared Spectroscopy Reveals Molecular Changes in Blood Vessels of Rats Treated with Pentadecapeptide BPC 157.

Recently, it was found that when confronted with major vessel occlusion and vascular failure, stable gastric pentadecapeptide BPC 157 therapy might rapidly functionally improve minor vessels to take over the function of disabled major vessels, reorganize blood flow, and compensate failed vessel function. We focused on the BPC 157 therapy effect obtained by giving 10 ng/kg ip to rats 5 min before sacrifice on the rat thoracic aorta, which we assessed with Fourier transform infrared spectroscopy (FTIR) 90 min thereafter. We applied a principal component analysis (PCA). The PCA model showed, with a clear distinction being mostly due to the PC1 score, differences between the spectra of BPC 157- and saline-treated rats. The comparison of the averaged spectra of these two groups with their differential spectrum and PC loadings allowed us to identify the parts of the FTIR spectra that contributed the most to the spectral separation of the two observed groups. The PC1 loadings and the differential spectrum showed that the main bands affecting the separation were the amid I band around 1650 cm-1, the amid II band around 1540 cm-1, and the vibrational band around 1744 cm-1. Fitting the spectral range between 1450 and 1800 cm-1 showed changes in protein conformation and confirmed the appearance of the vibrational band at 1744 cm-1. Controls had a substantially more intense vibrational band at 1744 cm-1. These spectral results showed the cells from saline-treated (control) rats to be in the early stage of cell death, while the samples from BPC 157-rats were protected. Thus, BPC 157 therapy changed the lipid contents and protein secondary structure conformation, with a rapid effect on vessels, within a short time upon application.

Evaluation of vasodilatory effect and antihypertensive effect of chrysin through in vitro and sub-chronic in vivo study

Chrysin, a bioflavonoid belonging to the flavone, occurs naturally in plants such as the passionflower, honey and propolis. Few studies have demonstrated that chrysin can promote vasorelaxant activities in rats' aorta and mesenteric arteries. To date, no research has explored the signalling system routes that chrysin may utilise to produce its vasorelaxant action. Therefore, this study aimed to investigate the underlying mechanisms involved in chrysin-induced vasorelaxant in rats' aortic rings and assess the antihypertensive effect of chrysin in spontaneously hypertensive rats (SHRs). The findings revealed that chrysin utilised both endothelium-dependent and endothelium-independent mechanisms. The presence of L-NAME (endothelial NO synthase inhibitor), ODQ (sGC inhibitor), methylene blue (cGMP lowering agent), 4-AP (voltage-gated potassium channel inhibitor), atropine (muscarinic receptors inhibitor) and propranolol (β-adrenergic receptors inhibitor) significantly reduced the chrysin's vasorelaxant action. Furthermore, chrysin can reduce intracellular Ca2+ levels by limiting the extracellular intake of Ca2+ through voltage-operated calcium channels and blocking the intracellular release of Ca2+ from the sarcoplasmic reticulum via the IP3 receptor. These indicate that chrysin-induced vasorelaxants involved NO/sGC/cGMP signalling cascade, muscarinic and β-adrenergic receptors, also the potassium and calcium channels. Although chrysin had vasorelaxant effects in in vitro studies, the in vivo antihypertensive experiment discovered chrysin does not significantly reduce the blood pressure of SHRs following 21 days of oral treatment. This study proved that chrysin utilised multiple signalling pathways to produce its vasorelaxant effect in the thoracic aorta of rats; however, it had no antihypertensive effect on SHRs.

Hexokinase Activator Attenuates Type 2 Diabetes Mellitus and Associated Endothelial Dysfunction in HFF-STZ-Induced Diabetic Rat

Hexokinase is an enzyme involved in the glucose metabolism pathway. Magnesium is an inherent cofactor of the Hexokinase enzyme. The plethora of literature suggested that hexokinase level was decreased in diabetic rats. Sodium metavanadate shows insulin-mimetic action. We designed this work to determine the effect of magnesium on diabetes and associated vascular complications in rats. Type-2 diabetes was induced by a high-fat diet and a low dose of streptozotocin.. Diabetic rats were divided into groups, i.e. normal, diabetic, magnesium sulfate, sodium metavanadate, a combination of glibenclamide and metformin, a variety of sodium metavanadate with glibenclamide and metformin, and a combination of magnesium sulfate with glibenclamide and metformin. Magnesium sulfate was used as a hexokinase activator. Blood glucose levels were measured before initiation, between, and after 4 weeks of treatment. Biochemical and tissue parameters were estimated for additional confirmation. A vascular study took the contractile response of hydrogen peroxide in rat thoracic aortas of different groups. Statistical comparisons between groups were performed by two-tailed one-way ANOVA followed by the Dunnett test. P-values <0.05 were considered statistically significant. Treatment with magnesium sulfate and sodium metavanadate (S.M.V.) alone and in combination significantly (p<0.05) modified the elevated blood glucose and various altered biochemical parameters in diabetic rats. Treatment showed a significant decrease (p < 0.001) n elevated contractile responses of hydrogen peroxide in thoracic aortas of diabetic rats Vs Normal Control). Hexokinase activation by magnesium and sodium metavanadate significantly reduced (** p < 0.01) diabetes as well as vascular complications.

Development of Hydroxamate Derivatives Containing a Pyrazoline Moiety as APN Inhibitors to Overcome Angiogenesis

Aminopeptidase N (APN) was closely associated with cancer invasion, metastasis, and angiogenesis. Therefore, APN inhibitors have attracted more and more attention of scientists as antitumor agents. In the current study, we designed, synthesized, and evaluated one new series of pyrazoline-based hydroxamate derivatives as APN inhibitors. Moreover, the structure-activity relationships of those were discussed in detail. 2,6-Dichloro substituted compound 14o with R1 = CH3, showed the best capacity for inhibiting APN with an IC50 value of 0.0062 ± 0.0004 μM, which was three orders of magnitude better than that of the positive control bestatin. Compound 14o possessed both potent anti-proliferative activities against tumor cells and potent anti-angiogenic activity. At the same concentration of 50 μM, compound 14o exhibited much better capacity for inhibiting the micro-vessel growth relative to bestatin in the rat thoracic aorta ring model. Additionally, the putative interactions of 14o with the active site of APN are also discussed. The hydroxamate moiety chelated the zinc ion and formed four hydrogen bonds with His297, Glu298 and His301. Meanwhile, the terminal phenyl group and another phenyl group of 14o interacted with S2' and S1 pockets via hydrophobic effects, respectively.

ITRAQ-based Proteomics Analysis of ADTM for Preventing the Development of Nitroglycerin-induced Tolerance

Background: Long-term nitroglycerin (NTG) therapy causes tolerance, which limits its clinical application. Previous studies have reported a novel Danshensu/tetramethylpyrazine derivative ADTM, which displays strong cardioprotective effects. However, the effect of ADTM is not known in the NTGinduced tolerance model. In this study, we aimed to evaluate the potential improvement and underlying mechanism of ADTM for preventing the development of NTG-induced tolerance in in vivo and in vitro experiments. Methods: Firstly, the effect of ADTM was determined on NTG-induced tolerance using isolated thoracic aortic rings obtained from rats (50 μM for 45 min). After intragastric administration of ADTM (30 mg/kg, twice a day) for 7 days, NTG solution (10 mg/kg) was subcutaneously injected into male Sprague-Dawley (SD) rats once a day for 7 consecutive days. The systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and mean arterial pressure (MAP) were recorded using the PowerLab system. The iTRAQ-based proteomics analysis was used to clarify the underlying mechanism of ADTM in NTG-induced tolerance. Results: ADTM markedly enhanced relaxation sensitivity and vasodilator responses to NTG tolerance in the isolated rat thoracic aorta, and this effect was independent of the vascular endothelium. ADTM prevented the development of NTG-induced tolerance in rats by improving hemodynamic parameters, such as SAP, DAP, and MAP. The iTRAQ-based proteomic analysis suggests that ADTM prevention of NTGinduced tolerance may be related to the regulation of ribosomal metabolism and tight junctions. Conclusion: These results indicate that ADTM has therapeutic potential for NTG-induced tolerance, and is worthy of further studies.

Vasorelaxant Effects of Syzygium samarangense (Blume) Merr. and L.M.Perry Extract Are Mediated by NO/cGMP Pathway in Isolated Rat Thoracic Aorta.

Syzygium samarangense (Blume) Merr. and L.M.Perry is utilized widely in traditional medicine. We have reported previously a wide array of pharmacological properties of its leaf extract, among them anti-inflammatory, antioxidant, hepatoprotective, antidiabetic, antiulcer, and antitrypanosomal activities. We also annotated its chemical composition using LC-MS/MS. Here, we continue our investigations and evaluate the vasorelaxant effects of the leaf extract on aortic rings isolated from rats and explore the possible underlying mechanisms. S. samarangense extract induced a concentration dependent relaxation of the phenylephrine-precontracted aorta in the rat model. However, this effect disappeared upon removing the functional endothelium. Pretreating the aortic tissues either with propranolol or NG-nitro-L-arginine methyl ester inhibited the relaxation induced by the extract; however, atropine did not affect the extract-induced vasodilation. Meanwhile, adenylate cyclase inhibitor, MDL; specific guanylate cyclase inhibitor, ODQ; high extracellular KCl; and indomethacin as cyclooxygenase inhibitor inhibited the extract-induced vasodilation. On the other hand, incubation of S. samarangense extract with aortae sections having their intact endothelium pre-constricted using phenylephrine or KCl in media free of Ca2+ showed no effect on the constriction of the aortae vessels induced by Ca2+. Taken together, the present study suggests that S. samarangense extract dilates isolated aortic rings via endothelium-dependent nitric oxide (NO)/cGMP signaling. The observed biological effects could be attributed to its rich secondary metabolites. The specific mechanisms of the active ingredients of S. samarangense extract await further investigations.

Effect of sulfasalazine on endothelium-dependent vascular response by the activation of Nrf2 signalling pathway.

Background: Diabetes mellitus leads to endothelial dysfunction and accumulation of oxygen radicals. Sulfasalazine-induced Nrf2 activation reduces oxidative stress in vessels. Thus, in the present study, we investigated the effects of sulfasalazine on endothelial dysfunction induced by high glucose. We also ascribed the underlying mechanism involved in glucose-induced endothelial dysfunction. Methods: For this experiment we used 80 Wistar Albino rats thoracic aorta to calculate the dose response curve of noradrenaline and acetylcholine. Vessels were incubated in normal and high glucose for 2h. To investigate glucose and sulfasalazine effects the vessels of the high glucose group were pre-treated with sulfasalazine (300mM), JNK inhibitor (SP600125), and ERK inhibitor (U0126) for 30min. The dose response curve was calculated through organ bath. The eNOS, TAS, TOS, and HO-1 levels were estimated by commercially available ELISA kits. Results: In the high glucose group, the Emax for contraction was significantly higher (p < 0.001), and Emax for relaxation was lower than that of control. These functional changes were parallel with the low levels of eNOS (p < 0.05). High glucose vessel treated with sulfasalazine showed low Emax value for contraction (p < 0.001) however, the Emax for relaxation was significantly high (p < 0.001) when compared to high glucose group. In the JNK group, Emax for contraction and relaxation was inhibited (p < 0.001) compared to sulfasalazine treated vessels. HO-1 enzyme levels were significantly low (p < 0.01) with sulfasalazine but higher with ERK inhibitor (p < 0.05). Conclusion: High glucose induced endothelial dysfunction and sulfasalazine reduced damage in high glucose vessels by activating eNOS, antioxidant effect through HO-1 enzymes and particularly inducing Nrf2 via the ERK and JNK pathways.

Decellularized fish swim bladder patch loaded with mesenchymal stem cells inhibits neointimal hyperplasia.

We previously showed decellularized fish swim bladder can be used as vascular patch and tube graft in rats, mesenchymal stem cells (MSCs) have showed the capability to inhibit neointimal hyperplasia in different animal models. We hypothesized that decellularized fish swim bladder patch loaded with MSCs (bioinspired patch) can inhibit neointimal hyperplasia in a rat aortic patch angioplasty model. Rat MSCs were grown in vitro and flow cytometry was used to confirm their quality. 3.6 × 105 MSCs were mixed into 100 μl of sodium alginate (SA)/hyaluronic acid (HA) hydrogel, two layers of fish swim bladders (5 mm × 5 mm) were sutured together, bioinspired patch was created by injection of hydrogel with MSCs into the space between two layers of fish swim bladder patches. Decellularized rat thoracic aorta patch was used as control. Patches were harvested at days 1 and 14 after implantation. Samples were examined by histology, immunohistochemistry, and immunofluorescence. The decellularized rat thoracic aorta patch and the fish swim bladder patch had a similar healing process after implantation. The bioinspired patch had a similar structure like native aorta. Bioinspired patch showed a decreased neointimal thickness (p=.0053), fewer macrophages infiltration (p=.0090), and lower proliferation rate (p=.0291) compared to the double layers fish swim bladder patch group. Decellularized fish swim bladder patch loaded with MSCs can inhibit neointimal hyperplasia effectively. Although this is a preliminary animal study, it may have a potential application in large animals or clinical research.

Study on the vasodilatory activity of lotus leaf extract and its representative substance nuciferine on thoracic aorta in rats.

Lotus (Nelumbo nucifera) leaves are widely used for both edible and medicinal applications. For its further utilization, we studied the vasodilatory activity of lotus leaf extract for the first time. In this study, we obtained the extracts using different ratios of water and ethanol, which was followed by polarity-dependent extraction. We found that the CH2Cl2 layer exhibited better vasodilatory activity (EC50 = 1.21 ± 0.10 μg/ml). HPLC and ESI-HRMS analysis of the CH2Cl2 layer using the standard product as a control revealed that nuciferine (Emax = 97.95 ± 0.76%, EC50 = 0.36 ± 0.02 μM) was the main component in this layer. Further research revealed that nuciferine exerts a multi-target synergistic effect to promote vasodilation, via the NO signaling pathway, K+ channel, Ca2+ channel, intracellular Ca2+ release, α and β receptors, etc. Nuciferine exhibits good vasodilatory activity, and it exhibits the potential to be utilized as a lead compound.

MiRNA-26a reduces vascular smooth muscle cell calcification by regulating connective tissue growth factor

To investigate the regulatory role of miRNA-26a in vascular smooth muscle cell (VSMC) calcification by regulating connective tissue growth factor (CTGF). Rat thoracic aorta VSMCs (A7r5 cells) with induced calcification were treated with AR234960 agonist or transfected with miR-26a mimic, or with both treatments. Alizarin red staining was used to determine calcium deposition, and phosphatase (ALP) activity in the cells was measured. The mRNA and protein expressions of miR-26a, OPG, OPN, BMP-2 and collagen Ⅱ were detected using qPCR and Western blotting. The binding of miR-26a to CTGF was verified using dual luciferase reporter gene assay. After induced calcification, A7r5 cells showed gradually decreased miR-26a expression (P < 0.05) and progressively increased CTGF expression (P < 0.05) with the extension of induction time. Treatment of the cells with AR234960 obviously increased calcification in the cells, while transfection with miR-26a mimic significantly reduced cell calcification. The calcifying cells showed significantly increased ALP activity and expressions of OPN, BMP-2 and collagen Ⅱ (P < 0.05) and lowered OPG expression (P < 0.05), and treatment with AR234960 did not produce obvious effects on these changes (P > 0.05). Transfection with miR-26a mimic resulted in significantly decreased ALP activity and expressions OPN, BMP-2 and collagen Ⅱ expression (P < 0.05) and increased OPG expression (P < 0.05) in the calcifying cells. These effects of miR-26a mimic was significantly attenuated by treatment of the cells with AR234960 (P < 0.05). The result of luciferase reporter gene assay confirmed the binding of miR-26a to CTGF. miRNA-26a can effectively alleviate vascular calcification by lowering the level of CTGF, reducing ALP activity and the expressions of OPN, BMP-2 and collagen Ⅱ, and increasing the expression of OPG.

Design, synthesis and biological evaluation of dehydroabietic acid derivative as potent vasodilatory agents

Using dehydroabietic acid as the lead compound for structural modification, 25 dehydroabietic acid derivatives were synthesized. Among them, compound D1 not only showed the strongest relaxation effect on the aortic vascular ring in vitro (Emax = 99.5 ± 2.1%, EC50 = 3.03 ± 0.96 µM), but also significantly reduced systolic and diastolic blood pressure in rats at a dose of 2.0 mg/kg in vivo. Next, the vascular protective effect of the best active D1 and its molecular mechanism were further investigated by HUVECs. The results showed that D1 induced endothelium-dependent diastole in the rat thoracic aorta in a concentration-dependent manner. Endothelium removal or aortic ring pretreatment with NG-nitro-l-arginine methylester (l-NAME), 1H-[1,2,4]-oxadiazolo-[4,3-a]-quinoxalin-1-one (ODQ), and tetraethylammonium (TEA) significantly inhibited D1-induced relaxation. In addition, wortmannin, KT5823, triciribine, diltiazem, BaCl2, 4-aminopyridine, indomethacin, propranolol, and atropine attenuated D1-induced vasorelaxation. D1 increased the phosphorylation of eNOS in HUVECs Furthermore, D1 attenuated the expression of TNF-α-induced cell adhesion molecules such as ICAM-1 and VCAM-1. However, this effect was attenuated by the eNOS inhibitors l-NAME and asymmetric dimethylarginine (ADMA). The findings suggest that D1-induced vasorelaxation through the PI3K/Akt/eNOS/NO/cGMP/PKG pathway by activating the KCa, Kir and KV channels or muscarinic and β-adrenergic receptors, and inhibiting the l-type Ca2+ channels, which is closely related to the hypotensive action of the agent. Furthermore, D1 exhibits an inhibitory effect on vascular inflammation, which is associated with the observed vascular protective effects.

Effects of Cold Storage in Krebs-Henseleit Solution at +4 °C on Vasoreactivity of the Rat Thoracic Aorta

Aim: This study aimed to investigate whether endothelium-dependent and -independent relaxation responses can be preserved intact in the rat thoracic aorta after storage for 3, 6, and 18 hours in Krebs-Henseleit solution at +4 °C.&#x0D; Methods: Isolated organ bath model and 10-12 weeks old male Wistar rats were used to perform the experiments. To investigate the effect of endothelium-dependent relaxation factors, the cyclooxygenase inhibitor INDO was added to the Krebs-Henseleit solution to inhibit endogenous prostanoid synthesis. Submaximal contraction response was obtained with a single dose of PE and then ACh was administered cumulatively (10-9-10-4 M) to induce endothelium-dependent relaxation responses. Besides, smooth muscle-dependent relaxation responses were obtained by applying SNP cumulatively (10-9-10-5 M) following precontraction induced by PE. The statistical significance level was considered as p0.05). Besides, cumulatively administered ACh did not cause a significant change in endothelium-dependent relaxation responses (p&gt;0.05). Similarly, SNP did not modulate the endothelium-independent relaxation responses in aortic segments after storage for 3, 6, or 18 hours (p&gt;0.05).&#x0D; Conclusion: In the present study, the first physiological findings have been obtained that the endothelium-dependent and -independent contraction-relaxation responses of rat thoracic aortas can be preserved intact after storage periods of 3, 6, or 18 hours in Krebs-Henseleit solution at +4°C.

Prenatal hypothyroidism diminished exogenous NO-mediated diastolic effects in fetal rat thoracic aorta smooth muscle via increased oxidative stress

Maternal hypothyroidism is an important problem of modern healthcare and is reported to increase the risk of cardiovascular diseases in the offspring later in life. However, it is unclear whether hypothyroidism during pregnancy causes vascular damage in the fetal period. We established the prenatal hypothyroidism rat model and collected the fetuses at the 21th day of gestation (GD21). Thyroid hormone concentrations in maternal and offspring blood serum were assessed by enzyme-linked immunosorbent assay (ELISA). The thoracic aortas of the fetuses were isolated for microvessel functional testing and histochemical stainings. qPCR and Western blot were performed to access mRNA and protein expression. We found that the concentrations of thyroid hormones in the serum of pregnant rats and fetuses were significantly suppressed at GD21. The responses of the fetal thoracic aortas to SNP were significantly attenuated in the PTU group. However, no statistical difference was found between the two groups when treated with either inhibitor (ODQ) or activator (BAY58–2667) of sGC. The production of O2−• in the arterial wall was significantly increased in hypothyroid fetuses. Moreover, the level of NADPH oxidase (NOX) was increased, while superoxide dismutase 2 (SOD2) was down-regulated in the PTU group, ultimately contributing to the increased production of superoxide. Additionally, decreased SNP-mediated vasodilation found in fetal vessels was improved by either NOX inhibitor (Apocynin) or SOD mimic (Tempol). These results indicate that increased oxidative stress is probably the cause of the diminished diastolic effect of exogenous NO in the thoracic artery of prenatal hypothyroidism exposed fetuses.

Rosa damascena Miller essential oil relaxes rat thoracic aorta through the NO-cGMP-dependent pathway

AimThis study aimed to investigate the effects of Rosa damascena Mill. essential oil on the vascular activity of rat thoracic aorta and its underlying mechanisms. MethodsExperiments were performed using the isolated tissue bath model and Wistar rats. 0.1, 1, 10, and 100 µg/mL concentrations of rose oil were administered in all groups. To determine the vasoactive effects of rose oil, submaximal contractions were conducted by applying 10−5 M PE and 45 mM KCl separately in both endothelium-intact and -denuded segments. Time-matched distilled water groups were formed for control. To evaluate the role of endothelium-derived vasodilative factors, endothelium-intact segments were incubated with nitric oxide synthase inhibitor L-NAME, soluble guanylate cyclase inhibitor ODQ, and a non-selective cyclooxygenase inhibitor INDO. The statistical significance level was considered as p < 0.05. Results1, 10, and 100 µg/mL rose oil doses led to vasorelaxation in thoracic aortas precontracted with 10−5 M PE (p: 0.029, p: 0.000, p: 0.000, respectively). In precontracted thoracic aortas with 45 mM KCl, the significant effect of rose oil persisted, albeit slightly diminished. When the endothelium was removed, the relaxant effect of rose oil was partially reduced, but still significant (p: 0.035, p: 0.028, p: 0.000, respectively). Preincubations with L-NAME and ODQ significantly attenuated rose oil-induced relaxation of endothelium-intact aortas precontracted with 10−5 M PE. In contrast, preincubation INDO did not modulate rose oil-induced relaxation. ConclusionIn conclusion, it was shown for the first time that rose oil can significantly mediate vasorelaxation in both PE and KCl precontracted rat thoracic aortas. Rose oil induced vasodilation with or without endothelium in a concentration-dependent manner. It was also shown that rose oil-induced vasorelaxant effects were reduced by L-NAME or ODQ pretreatment, but not modulated by INDO. These results demonstrated that rose oil-induced endothelium-dependent vasodilation is mediated by the NO-cGMP-dependent pathway.

Geraniol and β-citronellol participate in the vasorelaxant effects of Rosa damascena Miller essential oil on the rat thoracic aorta

AimThis study aimed to investigate the vasoactive effects of Rosa damascena Miller essential oil and its major components, geraniol and β-citronellol, on the rat thoracic aorta. MethodsIsolated tissue bath model and Wistar rats were used to perform the experiments. Two-fold increasing concentrations (20–160 μg/mL) of rose oil were administered to determine its vasoactive effects. Submaximal contractions were induced by PE or KCl in both endothelium-intact and -denuded segments. Time-matched control groups were also formed. To evaluate the role of geraniol and β-citronellol, concentrations in the range of 0.4–3.2 μg/mL and 0.8–6.4 μg/mL were applied respectively. The statistical significance level was considered as p < 0.05. ResultsAll doses of rose oil applied led to vasorelaxation in thoracic aortas precontracted with PE. In precontracted thoracic aortas with KCl, the significant effect of rose oil persisted, albeit slightly diminished. When the endothelium was removed, the relaxant effect of rose oil was partially reduced, but still significant. Besides, although geraniol relaxed aortic segments at all concentrations (0.4 to 3.2 μg/mL), β-citronellol caused vasorelaxation at doses of 1.6, 3.2, and 6.4 μg/mL. ConclusionIn conclusion, the first findings were obtained that rose oil can cause a vasorelaxant effect in a concentration-dependent manner in rat thoracic aorta. This effect substantially persisted in vascular segments without endothelium or precontracted with KCl. It was further shown for the first time that geraniol and β-citronellol exert vasodilatory effects on the rat thoracic aorta. These results suggest that rose oil exhibits its vasorelaxant effect through geraniol and β-citronellol.