• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.6
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• pp.730-737
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• 2013

The purpose of this study is to investigate vasorelaxant effect of Epimedium koreanum(EK) extract on rabbit carotid artery. In this study, to determine vasorelaxant effect of EK extract on rabbit carotid artery, arterial rings with intact or damaged endothelium were used for experiment using organ bath, and were contracted by norepinephrine(NE). After being contracted, arterial rings were treated with EK extract in a dose-dependent manner To study its mechanism, the contracted arterial rings induced by NE were pretreated with indomethacin(IM), $N_{\omega}$-nitro-L-arginine(L-NNA), methylene blue(MB) or tetraethylammonium chloride(TEA) and 0.1 $mg/m{\ell}$ EK extract was added. To analyze the effect of the EK extract on influx of extracellular calcium chloride($Ca^{2+}$) in rabbit carotid artery, in $Ca^{2+}$-free krebs solution, krebs solution containing 1 mM $Ca^{2+}$ was infused into the contracted arterial ring by NE after pretreatment of EK extract. To measure the cytotoxicity of the EK extract, cell viability of human umbilical vein endothelial cell(HUVEC) was measured by MTT assay, and nitric oxide(NO) was measured by Griess reagent. The EK extract significantly was relaxed the arterial ring with intact endothelium contracted by NE, but the vasorelaxant effect of the EK extract was inhibited in the arterial rings with damaged endothelium. The vasorelaxant effect of the EK extract was not different between the IM-pretreatedand and non-treated arterial rings. The vasorelaxant effect of EK extract were significantly inhibited, when arterial rings were pretreated with L-NNA, TEA, MB. And in $Ca^{2+}$-free krebs solution, increasing of arterial contraction by $Ca^{2+}$ addition were also inhibited by the treatment of EK, but not significant. The treatment of EK extract was increased NO concentration in HUVEC. This study suggested that the vasorelaxant effect of EK extract would be related with EDHF and NO production and increasing of cyclic GMP.

• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.4
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• pp.437-445
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• 2013

This study was investigated to evaluate the vasorelaxant effect of Rubus coreanus(RC) extract on contracted rabbit carotid artery and its mechanism. To study the effect of RC extract on contracted rabbit carotid arterial strips, arterial strips with intact or damaged endothelium were used for experiment using organ bath. The pre-contracted arterial strips with norepinephrine(NE) or potassium chloride(KCl) was treated with various concentrations of an extract of RC(0.01, 0.03, 0.1, 0.3 and 1.0 $mg/m{\ell}$). To determine the mechanisms of RC-induced vasorelaxant, RC extract was infused into contracted arterial rings which had been pretreated by indomethacin(IM), tetraethylammonium chloride(TEA), $N{\omega}$-nitro-L-arginine (L-NNA), methylene blue(MB). And calcium chloride(Ca) 1 mM was infused into precontracted arterial ring induced by NE or KCl after treatment of RC extract in $Ca^{2+}$-free krebs solution. Cytotoxic activity of RC extract on human umbilical vein endothelial cell(HUVEC) was measured by MTT assay, and nitric oxide(NO) prodution was measured by Griess reagent. RC extract revealed significant relaxation on NE-induced arterial contraction, but didn't relax on KCl-induced arterial contraction. RC extract also had an effective relaxation to the intact endothelium arterial ring, but not the damaged endothelium arterial ring. Treatment of IM, TEA, L-NNA, MB reduced the relaxation of RC extract. Pretreatment of RC extract inhibited the contraction by influx of extracellular $Ca^{2+}$ in contracted arterial ring induced by NE, but it didn't work the contraction by influx of extracellular $Ca^{2+}$ in contracted arterial ring induced by KCl in $Ca^{2+}$-free krebs solution. RC extract increased nitric oxide production on HUVEC. This study indicated that the relaxation effect of RC extract on contracted rabbit carotid artery is related with NO-cGMP pathway, EDHF, prostacyclin.

• Journal of Chest Surgery
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• v.28 no.8
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• pp.742-746
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• 1995

The present study was aimed at investigating possible transmitter mechanisms in the endothelial cell layer in regulating the tone of the vascular smooth muscle. The thoracic aorta was isolated from the anesthetized male white rabbits and its helical strips were prepared. Electrical field stimulation was delivered to platinum wire electrodes positioned parallel to the vessel segment preconstricted with phenylephrine [3.5x10-6 mol/L at a distance of 1.5-2.0 mm. The electrical stimulation [70 V, 5 msec, 0.5-200 Hz caused either relaxation only [34% or a biphasic response [prolonged relaxation following a weak and transient contraction, 66% . The relaxation response was frequency- dependent, and at 200 Hz a complete relaxation was noted. Mechanical rubbing of the endothelial layer abolished or greatly attenuated the relaxation. The relaxation was also markedly attenuated in the presence of NG-nitro- L-arginine methyl ester [10-3mol/L or procaine hydrochloride [3.5x10-4mol/L . Tetrodotoxin,guanethidine, atropine or indomethacin failed to block or enhance the relaxation response to electrical field stimulation. It is concluded that the vascular endothelium in the aorta contains diffusible substances that regulates the function of the smooth muscle layer, in which relaxation is more prominent than contraction. Their release by the electrical stimualtion in vitro may not involve classic neuronal transmitter release mechanisms or metabolism of arachidonic acids by cyclooxygenase. The release of the relaxing agents may require an increase in cytosolic calcium level. The chemical nature of the relaxant may be, to a large extent, nitric oxide.

• Journal of Pharmacopuncture
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• v.6 no.2
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• pp.149-158
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• 2003

Objective : The purpose of this study was to investigate the effect of Bee Venom on the lipopolysaccharide, sodium nitroprusside and hydrogen peroxide induced expression phospholipase $A_2$ and calcium concentration in RAW 264.7 cells, a murine macrophage cell line. Method : The expression of phospholipase $A_2$ was determined by western blotting with corresponding antibodies, and the generation of intracellular calcium concentration was investigated by delta scan system in RAW 264.7 cells. Results : 1. Compared with control, expressions of lipopolysaccharide-induced phospholipase $A_2$ were decreased significantly by $1\;{\mu}g/{\mu}l$ of bee venom and decreased by 0.5, $5\;{\mu}g/{\mu}l$ of bee venom. 2. Compared with control, expressions of sodium nitroprusside-induced phospholipase $A_2$ were decreased significantly by $5\;{\mu}g/{\mu}l$ of bee venom but increased by 0.5, $5\;{\mu}g/{\mu}l$ of bee venom. 3. Compared with control, expressions of hydrogen peroxide-induced phospholipase $A_2$ were decreased significaltly by $1{\mu}g/{\mu}l$ of bee venom and decreased by $0.5\;{\mu}g/{\mu}l$ of bee venom but increased by $5\;{\mu}g/{\mu}l$ of bee venom. 4. Compared with control, lipopolysaccharide, sodium nitroprusside and hydrogen peroxide- induced intracellular calcium concentrations were decreased by 0.5, 1, $5\;{\mu}g/{\mu}l$ of bee venom and by indomethacin

• Journal of Food Hygiene and Safety
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• v.8 no.3
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• pp.157-161
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• 1993

In order to get infonnations on the development of alcohol induced cardiovascular disorders, primary cultured vascular smooth muscle cells (PVSMC) were treated with acetaldehyde, one of the most reactive metabolites of ethanol. Acetaldehyde caused the striking release of lactate dehydrogenase (LDH) from PVSMC and it stimulated the prostaglandin synthesis in the same system. But it didn't induce cyclooxygenase activity. lipoxygenase inhibitors-propyl gallate and nordihydroguaiaretic acid could reverse the effect of acetaldehyde, but dexamethasone, a phospholipase $A_2\;(PIA_2)$ inhibitor and cyclooxygenase inhibitors except indomethacin could not protect the cells from acetaldehyde toxicity. These results indicate that enhanced prostaglandin synthesis by acetaldehyde is not a direct cause of cell death, but secondary effect due to the activation of PIAl and also, the roles of the lipoxygenase metabolites and/or $PIA_2$ activity itself might be more important in the cytotoxicity of acetaldehyde.

• Environmental Analysis Health and Toxicology
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• v.22 no.2 s.57
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• pp.137-145
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• 2007

The effect of cadmium chloride $(CdCl_2)$ on the expression of E-cadherin was examined in bEnd.3 mouse brain endothelial cells. $CdCl_2$ induced $PGE_2$ release, which were blocked by non-steroidal antinflamatory drugs (NSAIDs) such as indomethacin and NS398 indicating the expression of COX-2 might contribute to $PGE_2$ production. $CdCl_2$ decreased the expression of E-cadherin, but not VE-cadherin at levels of mRNA and protein. Reduced expression level of E-cadherin was restored by NSAIDs, which was reversed by the addition of $PGE_2$. $CdC_2$-induced decrease of E-cadherin level was also recovered by antioxidants including N-acetylcyteine (NAC) and trolox. Together with previous report which showed $CdCl_2$ induced COX-2 expression in a cellular oxidative stress dependent manner, these data suggest that $CdCl_2$ decreases E-cadherin expression through induction of cellular oxidative stress and in turn COX-2 expression in brain endothelial cells.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.3
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• pp.263-270
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• 2000

To evaluate the involvement of nitric oxide production on the endothelium-dependent relaxation in diabetes, we have measured vascular and endothelial function and nitric oxide concentration, and the expression level of endothelial nitric oxide synthase in the streptozotocin-induced diabetic rats. Diabetic rats were induced by the injection of streptozotocin (50 mg/kg i.v.) in the Sprague-Dawley rats. Vasoconstrictor responses to norepinephrine (NE) showed that maximal contraction to norepinephrine $(10^{-5}\;M)$ was significantly enhanced in the aorta of diabetic rats. Endothelium-dependent relaxation induced by acetylcholine was markedly impaired in the aorta of diabetic rats, these responses were little improved by the pretreatment with indomethacin. However, endothelium-independent relaxation induced by nitroprusside was not altered in the diabetic rats. Plasma nitrite and nitrate $(NO_2/_3)$ levels in diabetic rats were significantly lower than in non-diabetic rats. Western blot analysis using a monoclonal antibody against endothelial cell nitric oxide synthase (eNOS) revealed that the protein level was lower in the aorta of diabetic rats than in non-diabetic rats. These data indicate that nitric oxide formation and eNOS expression is reduced in diabetes, and this would, in part, account for the impaired endothelium-dependent relaxation in the aorta of streptozotocin-induced diabetic rats.

• YAKHAK HOEJI
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• v.40 no.4
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• pp.456-461
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• 1996

The effects of human epidermal growth factor(EGF) which was produced by recombinant DNA technique was investigated on gastric secretion, gastric lesion and ulcer models in rats. The EGF showed significant inhibition of secretion of gastric juice and total acid output, at 0.4mg/kg, id and also inhibited Shay ulceration at 0.4mg/kg, id in rats. The lesion induced by absolute ethanol was significantly reduced by oral administration of EGF at 0.4mg/kg. Likewise, EGF caused significant inhibition of indomethacin induced gastric ulcer at oral doses of 0.2 and 0.4mg/kg. The EGF produced dose-dependent inhibition of gastric ulcer induced by acidified aspirin, but showed no significant inhibition at oral doses of 0.1, 0.2 and 0.4mg/kg. The chronic gastric ulcer induced by injection of 20% acetic acid solution was significantly reduced by oral doses of 0.1 and 0.4mg/kg of EGF. Duodenal ulcer induced by mepirizole was dose-dependently inhibited by oral doses of 0.1, 0.2 and 0.4mg/kg of EGF. These data suggest that EGF possesses pronounced inhibitory action in gastric ulcer and duodenal ulcer of rats.

• Korean Journal of Veterinary Research
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• v.43 no.4
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• pp.587-595
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• 2003

The aim of this study was to investigate trazodone's effect on vasorelaxation and blood pressure lowering and to examine its underlying mechanism of action in isolated thoracic aorta and anesthesized rats. Precontracted aortic rings with high KCl were relaxed with trazodone, at concentrations of $50{\mu}M$ or greater. However, precontracted rings with phenylephrine (PE) were relaxed with trazodone, at concentrations of $0.03{\mu}M$ or greater, in a concentration-dependent manner. These relaxant effects of trazodone on endothelium intact rat aortic rings were significantly greater than those on denuded rings. The trazodone-induced relaxations were suppressed by nitric oxide synthase (NOS) inhibitors, N(G)-nitro-L-arginine (L-NNA) and N(omega)-nitro-L-arginine methyl ester (L-NAME), guanylate cyclase inhibitors, methylene blue and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a $Ca^{2+}$-activated $K^+$ channel blocker, tetrabutylammonium (TBA), a $Ca^{2+}$ channel blocker, nifedipine, $Na^+$ channel blockers, lidocaine and procaine, and removal of extracellular $Na^+$, but not by aminoguanidine, 2-nitro-4-carboxyphenyl-n, n-diphenylcarbamate (NCDC), indomethacin, glibenclamide and clotrimazole. In vivo, infusion of trazodone elicited significant decrease in arterial blood pressure. Trazodone-induced decrease in blood pressure was markedly inhibited by pretreatment of intravenous injection of saponin, L-NNA, methylene blue, TBA, lidocaine or nifedipine. These findings suggest that the endothelium-dependent relaxation and decrease in blood pressure induced by trazodone is mediated by release of NO from the endothelium, activation of TBA-sensitive $Ca^{2+}$-activated $K^+$ channels or inhibition of $Ca^{2+}$ entry through voltage-gated channel.

• Korean Journal of Veterinary Research
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• v.43 no.4
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• pp.597-606
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• 2003

Although the antidepressant effects of imipramine (IMI) have been well known in several studies, the effects on cardiovascular system, particularly the vasorelaxant effects, have not known clearly. We hypothesis that IMI-induced vasorelaxation involves NO (nitrie oxide), activation of guanylate cyclase (GC) and $Ca^{2+}$ channel. The possible roles of the endothelium and $Ca^{2+}$ in IMI-induced responses were investigated using isolated rings of rat thoracic aorta and anesthesized rats. In KCl-precontracted rings. IMI produces endothelium-dependent and endothelium-independent relaxations in intact (+E) as well as endothelium-denuded (-E) rat aorta in a concentration-dependent manner. In phenylephrine (PE)-precontracted rings, the IMI-induced relaxation was significantly greater in +E rings. The IMI-induced relaxations were suppressed by nitric oxide synthase (NOS) inhibitors, N(G)-nitro-L-arginine (L-NNA), N(omega)-nitro-L-arginine methyl ester (L-NAME) and aminoguanidine, a non-selective GC inhibitor, methylene blue, $Na^+$ channel blockers, lidocaine and procaine, or $Ca^{2+}$ channel blockers, nifedipine and verapamil, in PE-precontracted +E rings, but not in PE-precontracted -E rings. These relaxations were also suppressed by lidocaine or procaine in -E aortic rings. However, IMI-induced relaxations were not inhibited by a PLC inhibitor 2-nitro-4-carboxyphenyl-n,n-diphenylcarbamate (NCDC), an inositol monophosphatase inhibitor, lithium, indomethacin and dexamethasone in +E and -E rings. In vivo, infusion of IMI elicited significant decrease in arterial blood pressure. After intravenous injection of saponin, NOS inhibitors. MB and nifedipine, infusion of IMI inhibited the IMI-lowered blood pressure markedly. These findings suggest that the endothelium-dependent relaxation induced by IMI is mediated by activation of NO/cGMP signaling cascade or inhibition of $Ca^{2+}$ entry through voltage-gated channel, and this mechanism may contribute to the hypotensive effects of IMI in rats.