• Biomolecules & Therapeutics
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• v.18 no.2
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• pp.135-144
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• 2010

The pro-oxidative and pro-inflammatory pathways in vascular endothelium have been implicated in the initiation and progression of atherosclerosis. In fact, inflammatory responses in vascular endothelium are primarily regulated through oxidative stress-mediated signaling pathways leading to overexpression of pro-inflammatory mediators. Enhanced expression of cytokines, chemokines and adhesion molecules in endothelial cells and their close interactions facilitate recruiting and adhering blood leukocytes to vessel wall, and subsequently stimulate transendothelial migration, which are thought to be critical early pathologic events in atherogenesis. Although interleukin-4 (IL-4) was traditionally considered as an anti-inflammatory cytokine, recent in vitro and in vivo studies have provided robust evidence that IL-4 exerts pro-inflammatory effects on vascular endothelium and may play a critical role in the development of atherosclerosis. The cellular and molecular mechanisms responsible for IL-4-induced atherosclerosis, however, remain largely unknown. The present review focuses on the distinct sources of IL-4-mediated reactive oxygen species (ROS) generation as well as the pivotal role of ROS in IL-4-induced vascular inflammation. These studies will provide novel insights into a clear delineation of the oxidative mechanisms of IL-4-mediated stimulation of vascular inflammation and subsequent development of atherosclerosis. It will also contribute to novel therapeutic approaches for atherosclerosis specifically targeted against pro-oxidative and pro-inflammatory pathways in vascular endothelium.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.2
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• pp.209-216
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• 1998

The present study was designed: (1) to determine whether or not hypoxia stimulates the release of endothelium-derived relaxing factors (EDRFs) from endothelial cells, and (2) to examine whether or not the hypoxia-induced EDRFs release is further augmented by previous hypoxia-reoxygenation, using bioassay system. In the bioassay experiment, rabbit aorta with endothelium was used as EDRFs donor vessel and rabbit carotid artery without endothelium as a bioassay test ring. The test ring was contracted by prostaglandin $F_{2{\alpha}}$ $(3{\times}10^{-6}\;M/L)$, which was added to the solution perfusing through the aortic segment. Hypoxia was evoked by switching the solution aerated with 95% $O_2/5%\;CO_2$ mixed gas to one aerated with 95% $N_2/5%\;CO_2$ mixed gas. When the contraction induced by prostaglandin $F_{2{\alpha}}$ reached a steady state, the solution was exchanged for hypoxic one. And then, hypoxia and reoxygenation were interchanged at intervals of 2 minutes (intermittent hypoxia). The endothelial cells were also exposed to single 10-minute hypoxia (continuous hypoxia). When the bioassay ring was superfused with the perfusate through intact aorta, hypoxia relaxed the precontracted bioassay test ring markedly. Whereas, when bioassay ring was superfused with the perfusate through denuded aorta or polyethylene tubing, hypoxia relaxed the precontracted ring slightly. The relaxation was not inhibited by indomethacin but by nitro-L-arginine or methylene blue. The hypoxia-induced relaxation was further augmented by previous hypoxia-reoxygenation and the magnitude of the relaxation by intermittent hypoxia was significantly greater than that of the relaxation by continuous hypoxia. The results suggest that hypoxia stimulates EDNO release from endothelial cells and that the hypoxia-induced EDNO release is further augmented by previous hypoxia-reoxygenation.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.6
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• pp.313-317
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• 2004

The present study were designed to characterize the action mechanisms of acetylcholine (ACh)-induced endothelium-dependent relaxation in arteries precontracted with high $K^+$(70 mM). For this, we simultaneously measured both muscle tension and cytosolic free $Ca^{2+}$ concentration $([Ca^{2+}]_i)$, using fura-2, in endothelium-intact, rabbit carotid arterial strips. In the artery with endothelium, high $K^+$ increased both $[Ca^{2+}]_i$ and muscle tension whereas ACh $(10{\mu}M)$ significantly relaxed the muscle and increased $[Ca^{2+}]_i$. In the presence of $N^G$-nitro-L-arginine (L-NAME, 0.1 mM), ACh increased $[Ca^{2+}]_i$ without relaxing the muscle. In the artery without endothelium, high $K^+$ increased both $[Ca^{2+}]_i$ and muscle tension although ACh was ineffective. 4-DAMP (10 nM) or atropine $(0.1{\mu}M)$ abolished ACh-induced increase in $[Ca^{2+}]_i$ and relaxation. The increase of $[Ca^{2+}]_i$ and vasorelaxation by ACh was siginificantly reduced by either $3{\mu}M$ gadolinium, $10{\mu}M$ lanthanum, or by $10{\mu}M$ SKF 96365. These results suggest that in rabbit carotid artery, ACh-evoked relaxation of 70 mM $K^+$-induced contractions appears to be mediated by the release of NO. ACh-evoked vasorelaxation is mediated via the $M_3$ subtype, and activation of the $M_3$ subtype is suggested to stimulate nonselective cation channels, leading to increase of $[Ca^{2+}]_i$ in endothelial cells.

• Korean Journal of Veterinary Research
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• v.43 no.4
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• pp.573-578
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• 2003

The effects of removing the endothelium on the vasodilatory response to substance P, calcitonin gene-related peptide (CGRP), and vasoactive intestinal peptide (VIP) was examined in the isolated rabbit renal artery. The vasodilator response to substance P ($0.1{\mu}M$) was completely absent in vessels in which the endothelium had previously been removed. There was no significant difference in the vasodilatation produced in response to CGRP ($0.1{\mu}M$), or VIP ($0.1{\mu}M$) in the intact and removed-endothelium rabbit renal artery segments. L-NAME ($100{\mu}M$) significantly reduced the vasodilatory response to substance P ($0.1{\mu}M$). This inhibition was significantly attenuated when L-arginine (10 mM) was also present in the organ bath along with L-NAME ($100{\mu}M$). Indomethacin ($1{\mu}M$) did not significantly affect the vasodilatation produced in response to substance P ($0.1{\mu}M$). The inhibitory effect of L-NAME ($100{\mu}M$) and indomethacin ($1{\mu}M$) on the vasodilatory response to substance P ($0.1{\mu}M$) was not significantly different from that produced by L-NAME ($100{\mu}M$) alone. This study indicates that substance P induced vasodilatation via an endothelium-dependent mechanism in the isolated rabbit renal artery. It also established that CGRP and VIP induced vasodilatation by an endothelium-independent mechanism and substance P-induced vasodilatation is at least partially via NO.

• Herbal Formula Science
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• v.17 no.2
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• pp.175-186
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• 2009

The vasorelaxant effect of an extract of Lophatherum gracile Brongn (ELB) and its possible action mechanism were ascertained in aortic tissues isolated from rats. ELB relaxed endothelium-intact thoracic aorta in a dose-dependent manner. However, the induced vascular relaxation was abolished by removal in endothelium of the thoracic aorta. Pretreatment of endothelium-intact vascular tissues with $N^G$-nitro-L-arginine methyl ester (L-NAME) or 1H-[1,2,4]-oxadiazole-[4,3-$\alpha$]-quinoxalin-1-one (ODQ) significantly inhibited vascular relaxation induced by ELB. Moreover, ELB significantly increased cGMP production in aortic tissues, which was blocked by pretreatment with L-NAME or ODQ. The vasorelaxant effect of ELB was attenuated by tetraethylammonium (TEA), and glibenclamide. ELB-induced vasorelaxation was not blocked by atropine, propranolol, indomethacin, verapamil, and diltiazem. Taken together, the present study demonstrates that ELB dilates vascular smooth muscle via an endothelium-dependent NO-cGMP signaling pathway, which may be at least in part related with the function of $K^+$ channels.

• Journal of Physiology & Pathology in Korean Medicine
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• v.30 no.2
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• pp.101-108
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• 2016

This study is conducted to investigate vasorelaxant effect of Corni Fructus(CF) on rabbit carotid artery. To determine vasorelaxant effect of CF on rabbit carotid artery, arterial sections with intact or removed endothelium were used in this organ bath study. After being contracted by phenylephrine(PE), arterial sections were treated with CF extract in a dose-dependent manner. To identity its mechanism, the contracted arterial sections by PE were pretreated with indomethacin(IM), tetraethylammonium chloride(TEA), Nω-nitro-L-arginine(L-NNA) or methylene blue(MB) and 1.0 ㎎/㎖ CF extract. We also studied to confirm the effect on influx of extracellular calcium chloride(Ca²⁺) of the CF extract in rabbit carotid artery. To measure the cytotoxicity of the CF extract, cell viability of human umbilical vein endothelial cell(HUVEC) was measured by MTT assay. Generation of nitric oxide(NO) was also measured by Griess reagent. The arterial sections with intact endothelium were relaxed significantly by CF extract, but this effect was inhibited in the arterial sections with damaged endothelium. The vasorelaxant effect was inhibited significantly when arterial sections were pretreated with IM, TEA, L-NNA, MB. In Ca²⁺-free krebs solution, increasing of arterial contraction by Ca²⁺ was also inhibited by CF significantly. The treatment of CF extract increased NO concentration in HUVEC. This study suggested that the vasorelaxant effect of CF extract would be related with endothelium derived relaxing factor(EDRF) such as NO, prostacyclin(PGI₂), endothelium derived hyperpolarization factor(EDHF).

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.3
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• pp.593-599
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• 2008

This research was aimed to examine the effect of Polygoni Multiflori Radix extract on the blood pressure in spontaneous hypertensive rat (SHR) and norepinephrine - induced arterial contraction in rabbit. In order to investigate the effect of Polygoni Multiflori Radix on rabbit's contracted vascular ring detached from common carotid artery, vascular ring with intact or damaged endothelium was used for the experiment using organ bath. To analyze the mechanism of Polygoni Multiflori Radix-induced relaxation, Polygoni Multiflori Radix extract was infused into contracted vascular ring which had been pretreated by $N{\omega}$-nitro-L-arginine(L-NNA), Methylene blue(MB), and $Ca^{2+}$ was infused into contracted vascular ring induced by NE after treatment of Polygoni Multiflori Radix extract in $Ca^{2+}$-free solution. The results were as follows: Systolic blood pressure was significantly attenuated by administration of Polygoni Multiflori Radix. Blood flow and aldosterone were significantly decreased, but velocity and renin were not affected by Polygoni Multiflori Radix. Polygoni Multiflori Radix had an effective relaxation to the contracted vascular ring by NE in 0.03 mg/ml, 0.1 mg/ml and 0.3 mg/ml level. Polygoni Multiflori Radix had an effective relaxation to the intact endothelium vascular ring, but when endothelium was removed, vascular ring did not relax. Polygoni Multiflori Radix-induced relaxation was inhibited by the pretreatment of L-NNA and MB. Pretreatment of Polygoni Multiflori Radix extract inhibit the contraction by influx of extra-$Ca^{2+}$ in contracted vascular ring induced by NE in $Ca^{2+}$-free solution. As mentioned above, we suggest that Polygoni Multiflori Radix relaxes vascular ring through suppress influx of extra-cellular $Ca^{2+}$ by the action of nitric oxide from endothelium.

• Journal of Chest Surgery
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• v.24 no.7
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• pp.637-646
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• 1991

Effect of noradrenaline and endothelium on the high K+ or Ach-induced contraction were investigated in the pig myocardial coronary artery. The helical strip of isolated pig myocardial coronary artery was immersed in the Tris-buffered Tyrode`s solution equilibrated with 100% O2 at 37oC and its isometric tension was measured. High K+ and Ach-induced contraction were dose-dependent. By denuding the endothelium, dose-contraction curve of K+ was not shifted significantly to the left and upward, but that of Ach was shifted significantly to same direction 25 mM K+ - and Ach-induced contraction were relaxed by norepinephrine[NE]. NE-induced relaxation was blocked by the pretreatment of propranolol, which was known as b-adrenoceptor blocker. And, phenylephrine known as a-adrenoceptor agonist, and clonidine known as a-adrenoceptor agonist increased the 25mM K+ - induced contraction respectively. Denuding of endothelium did not show any significant effects on NE-induced relaxation and contraction increased by phenylephrine and clonidine. Tyramine increased 25mM K+ - induced contraction further. The contractile response by tyramine on the 25mM K+ - induced contraction was not blocked by the pretreatment of phentolamine, but was partially blocked by the pretreatment of atropine. From the above results, it is suggested that activation of a1-and a2-adrenoceptors induce the contraction, activation of b-adrenoceptors induce the relaxation, and NE-induced relaxation is mainly due to activation of b-adrenoceptors. Also it is suggested that denudation of endothelium did not influence NE-induced relaxation, but influence Ach-induced contraction in the pig myocardial coronary artery.

• The Korea Journal of Herbology
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• v.30 no.6
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• pp.25-32
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• 2015

Objectives : The purpose of this study was to investigate the endothelium-dependent vasorelaxation effect of Cynomorii Herba(CH) extract on contracted rabbit carotid artery.Methods : To clarify the vasorelaxation effect of CH extract, arterial strips with intact was used, to endothelium -dependent vasorelaxation effect of CH extract, arterial strips damaged endothelium was used for experiment using organ bath. Arterial strips was contracted with phenylephrine(PE) before treated with CH extract(0.01, 0.03 and 0.1 ㎎/㎖). To study mechanisms of CH-induced vasorelaxation effect, CH extract infused into arterial rings after treatment by indomethacin(IM), tetraethylammonium chloride(TEA), Nω-nitro-L-arginine (L-NNA), methylene blue(MB) for comparing with non-treated. And calcium chloride(Ca²⁺) 1 mM was treated into precontracted arterial ring induced by PE after treatment of CH extract in Ca²⁺-free krebs solution. Cytotoxic activity of CH extract on human umbilical vein endothelial cell(HUVEC) was measured by MTT assay, and nitric oxide(NO) concentration was measured by Griess reagent.Results : PE-induced arterial strips was significantly relaxed, but the damaged endothelium arterial ring wasn't relaxed by CH extract. Pretreatment of IM, TEA didn't inhibit the vasorelaxation of CH extract, but pretreatment of L-NNA, MB inhibited the vasorelaxation of CH extract. Pretreatment of CH extract reduced the increase of contraction by influx of extracellular Ca²⁺ in contracted arterial ring induced by PE, CH extract increased nitric oxide concentration on HUVEC significantly.Conclusions : This study shows that CH extract have the vasorelaxation effect by blocking the influx of extracellular Ca²⁺ through the activating NO-cGMP system.

• Preventive Nutrition and Food Science
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• v.15 no.3
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• pp.189-195
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• 2010

Water extracts from 20 medicinal plants, traditionally used for postmenopausal symptoms in Korea, were examined for their vasorelaxant activity in isolated rat thoracic aorta rings precontracted with norepinephrine (NE). Among the 20 medicinal plants, Cornus officinalis (CoEx, 0.3 mg/mL), Schisandra chinensis (ScEx, 0.3 mg/mL), Erythrina variegate (EvEx, 0.3 mg/mL), and Epimedium koreanum (EkEx, 0.3 mg/mL) showed rapid relaxation of endothelium-intact aorta ($69\pm4%$, $40\pm3%$, $25\pm2%$, and $23\pm3%$ of active tone induced by NE, respectively). In contrast, the extracts of Erythrina variegata (EvEx), Angelica gigas (AgEx), Pueraria thunbergiana (PtEx), and EkEx lead to gradual (i.e., long-term) relaxation to baseline in endothelium-intact vessels. The time to complete relaxation was 20～40 min. These 6 plant extracts were selected for the investigation of possible underlying mechanisms. The CoEx-, ScEx-, or EkEx-induced rapid relaxations were virtually abolished by endothelium denudation, and were significantly inhibited by pretreatment with nitric oxide (NO) synthase inhibitor $N^G$-nitro-L-arginine (L-NNA, 10 ${\mu}M$), indicating that increased formation of NO might contribute to the endothelium-mediated relaxation. In long-term responses, the endothelium denudation did not affect PtEx-induced relaxation, whereas it delayed responses by EvEx and AgEx, and significantly inhibited the effect of EkEx. Among EvEx, AgEx, and PtEx, EvEx attenuated the $CaCl_2$-induced vasoconstriction in high-potassium depolarized medium, implying that EvEx is involved in inhibition of the extracellular calcium influx to smooth muscle through voltage dependent calcium channels. These results provide the scientific rationale for the interrelationships between the use of 20 medicinal plants and their effects on cardiovascular health in estrogen deficient conditions.