• Journal of Chest Surgery
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• v.46 no.6
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• pp.402-412
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• 2013

Background: Moderate and severe hypothermia with cardiopulmonary bypass during aortic surgery can cause some complications such as endothelial cell dysfunction or coagulation disorders. This study found out the difference of vascular reactivity by phenylephrine in moderate and severe hypothermia. Methods: Preserved aortic endothelium by excised rat thoracic aorta was sectioned, and then down the temperature rapidly to $25^{\circ}C$ by 15 minutes at $38^{\circ}C$ and then the vascular tension was measured. The vascular tension was also measured in rewarming at $25^{\circ}C$ for temperatures up to $38^{\circ}C$. To investigate the mechanism of the changes in vascular tension on hypothermia, NG-nitro-L-arginine methyl esther (L-NAME) and indomethacin administered 30 minutes before the phenylephrine administration. And to find out the hypothermic effect can persist after rewarming, endothelium intact vessel and endothelium denuded vessel exposed to hypothermia. The bradykinin dose-response curve was obtained for ascertainment whether endothelium-dependent hyperpolarization factor involves decreasing the phenylnephrine vascular reactivity on hypothermia. Results: Fifteen minutes of the moderate hypothermia blocked the maximum contractile response of phenylephrine about 95%. The vasorelaxation induced by hypothermia was significantly reduced with L-NAME and indomethacin administration together. There was a significant decreasing in phenylephrine susceptibility and maximum contractility after 2 hours rewarming from moderate and severe hypothermia in the endothelium intact vessel compared with contrast group. Conclusion: The vasoplegic syndrome after cardiac surgery might be caused by hypothermia when considering the vascular reactivity to phenylephrine was decreased in the endothelium-dependent mechanism.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.1
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• pp.1-8
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• 2001

Hyperpolarization of arterial smooth muscle by acetylcholine is considered to be produced by the release of an unidentified chemical substance, an endothelium-derived hyperpolarizing factor (EDHF). Several chemicals have been proposed as the candidate for EDHF. However, none of them fulfil completely the nature and property of EDHF. Ultrastructural observation with electron microscope reveals that in some arteries, gap junctions are formed between endothelial and smooth muscle cells. In small arterioles, injection of gap junction permeable dyes into an endothelial cell results in a distribution of the dye to surrounding cells including smooth muscle cells. These observations allow the speculation that myoendothelial gap junctions may have a functional significance. Simultaneous measurement of the electrical responses in both endothelial and smooth muscle cells using the double patch clamp method demonstrates that these two cell types are indeed electrically coupled, indicating that they behave as a functional syncytium. The EDHF-induced hyperpolarization is produced by an activation of $Ca^{2+}-sensitive\;K^+-channels$ that are inhibited by charybdotoxin and apamin. Agonists that release EDHF increase $[Ca^{2+}]_i$ in endothelial cells but not in smooth muscle cells. Inhibition of gap junctions with chemical agents abolishes the agonist-induced hyperpolarization in smooth muscle cells but not in endothelial cells. All these observations can be explained if EDHF is an electrotonic signal propagating from endothelium to smooth muscle cells through gap junctions.

• 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).