• Korean Journal of Bronchoesophagology
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• v.4 no.1
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• pp.64-72
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• 1998

This study aimed at observing the effect of diazepam on the contractility of trachealis muscle isolated from canine trachea, possible involvement of central or peripheral type benzodiazepine receptor, and the calcium related mechanism of action of diazepam. Trachealis muscle strips of 15 mm long were suspended in an isolated organ bath containing 1 ml of physiologic salt solution maintained at $37^{\circ}C$, and aerated with 95% $O_2$ /5% $CO_2$. Isometric myography was performed. Diazepam reduced the basal tone concentration dependently, and this inhibitory action was not affected by neither flumazenil, a central benzodiazepine receptor antagonist, nor PK11195, a peripheral benzodiazepine receptor antagonist. Pretreatment with diazepam showed the inhibitory effect on the concentration-response curves to agonists such as bethanechol, 5-hydroxytryptamine and histamine. Diazepam also caused concentration-related inhibition of contraction with potassium chloride 30 mM. The effect of diazepam on the basal tone and potassium chloride-induced contraction with calcium channel blockers were compared. Similar results were obtained in canine trachealis with verapamil, nifedipine and diltiazem. These results suggest that diazepam relax an airway muscle not via specific receptors but by a similar action as calcium channel blockers in canine trachealis muscle.

• The Korean Journal of Physiology and Pharmacology
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• v.23 no.5
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• pp.295-303
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• 2019

A heart simulator, UT-Heart, is a finite element model of the human heart that can reproduce all the fundamental activities of the working heart, including propagation of excitation, contraction, and relaxation and generation of blood pressure and blood flow, based on the molecular aspects of the cardiac electrophysiology and excitation-contraction coupling. In this paper, we present a brief review of the practical use of UT-Heart. As an example, we focus on its application for predicting the effect of cardiac resynchronization therapy (CRT) and evaluating the proarrhythmic risk of drugs. Patient-specific, multiscale heart simulation successfully predicted the response to CRT by reproducing the complex pathophysiology of the heart. A proarrhythmic risk assessment system combining in vitro channel assays and in silico simulation of cardiac electrophysiology using UT-Heart successfully predicted drug-induced arrhythmogenic risk. The assessment system was found to be reliable and efficient. We also developed a comprehensive hazard map on the various combinations of ion channel inhibitors. This in silico electrocardiogram database (now freely available at http://ut-heart.com/) can facilitate proarrhythmic risk assessment without the need to perform computationally expensive heart simulation. Based on these results, we conclude that the heart simulator, UT-Heart, could be a useful tool in clinical medicine and drug discovery.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.6
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• pp.591-597
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• 2013

Because most existing non-Newtonian models are not suitable for application to the lattice Boltzmann method, theoretical and numerical studies in this regard remain challenging. In this study, the hydrokinetic (HK) model was modified and applied to a 3D sudden contraction-expansion channel flow, and the characteristics of the HK model flow were evaluated to generate non-trivial predictions in three-dimensional strong shear flows. The HK model is very efficient for application to the lattice Boltzmann method because it utilizes the shear rate and relaxation time. However, the simulation would be unstable in a high shear flow field because the local relaxation time sharply decreases with an increase in the shear rate in a strong shear flow field. In the HK model, it may become necessary to truncate the relaxation time and non-dimensional parameter to obtain stable numerical results.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.5
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• pp.1311-1316
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• 2005

This study was designed to potentiate the vasodilation effect of Banhabackchulchunma-Tang(BCT) prescription by change of mixture. Six different BCT compositions were made according to mixture of herbs. The vascular relaxation effects of 6 different BCT compositions were examined on phenylephrine(PE)-precontracted rat thoracic aorta. The BCT-1 composition exerted significant relaxation on phenylephrine- or KCI- contracted rat thoracic aorta. Its elaxation was endothelium- independent in both PE- and KCl-induced contraction. Treatment of glibenclamide or tetraethylammonium(TEA) did not affect the relaxation of BCT-1. Vasorelaxation efficacy of BCT-1 was also not influenced by low (25mM) or high (50mM, 80mM) KCl-induced contraction. Furthermore, the contraction by increasing $Ca^{2+}$ concentrations (0.3-10.0mM) to a $Ca^{2+}$-free high K+ (60mM) was significantly reduced by pretreatment with BCT-1 In addition, the relaxant effects were not inhibited by pretreatment of rat aorta with L-NAME, MB, indomethacin and atropine. These results confirm that BCT-1 may exerts its vasodilation effect by endothelium-independent manner. According to the above results, we suggest that the relaxation effect of BCT-1 is endothelium-independent and is related with block of $Ca^{2+}$ influx via $Ca^{2+}$ channel.

• The Journal of Korean Obstetrics and Gynecology
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• v.18 no.4
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• pp.72-84
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• 2005

Purpose : This study was carried out to investigate the relaxational response to the water extract of Sobokchukeo-Tang(SCT) in isolated uterine muscle in rats. Methods : Segments of uterine muscle obtained from female rats immediately after delivery were mounted in organ baths superfused on a polygraph. The effects of SCT on the tension of potassium induced contracture were studied in rat uterine smooth muscles. All experiments were performed in Krebs-Henseit solution which was aerated with 100% oxygen and kept at $37^{\circ}C$. Results : KCI did not produce contraction in calcium-free solution, but $CaCl_2$ induced concentration-dependent contraction after depolarizing with KCI. SCT inhibited the tonic contraction of uterine muscle as dose dependent manner. And when SCT was pretreated in calcium-free medium, it showed more powerful relaxational effect. The effect of 10mg/ml concentration of SCT was equal to that of 9nM and 70nM of nifedipine and verapamil and the relaxational effect of SCT on rat uterine muscle can be assumed to be concerned with the action of cyclic AMP. But the action mechanism of relaxation on the rat uterine muscles were concerned with the calcium channel. Conclusion : From this study we could suggest that the relaxtional effect of SCT on uterine muscle be available to preventing and curing dysmenorrhea.

• Journal of the Korean Society of Physical Medicine
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• v.11 no.2
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• pp.71-76
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• 2016

PURPOSE: The purpose of this study was to compare isometric contraction of deltoid middle fiber between elastic band and light dumbbell on various shoulder abduction angle. And this study intends to examine the compare with isometric contraction on deltoid middle fiber in various abduction angle of shoulder joint. METHODS: The participants of this study were Korean healthy adult in their 20s (n=60). The 8 channel surface electromyography was used to measure activity of the deltoid middle fiber at isomeric contraction on various abduction angle: $0^{\circ}$, $30^{\circ}$, $60^{\circ}$, $90^{\circ}$, $120^{\circ}$ of shoulder joint using elastic band: red color Theraband and dumbbell: 2kg. The data used in the analysis of the present study was the root mean square. RESULTS: The deltoid middle fiber activation was not significantly different between elastic band and dumbbell at each abduction angle. The deltoid middle fiber activation significantly increased as more to increased shoulder abduction angle in elastic band and dumbbell. CONCLUSION: The elastic band and dumbbell was to provide the similarly load to the deltoid middle fiber isometric contraction on all of the shoulder abduction angle. The deltoid middle fiber activation increased as more to increased shoulder abduction angle in elastic band and dumbbell. These results may be an important reference in development of exercise on shoulder joint.

• Journal of Ginseng Research
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• v.29 no.3
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• pp.119-125
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• 2005

The previous reports demonstrated that ginseng saponins, active ingredient of Panax ginseng, inhibited blood vessel contraction induced by various hormones or high $K^+$. Recently, we demonstrated that 20(R)- and 20(S)-ginsenoside $Rg_3$. regulate ion channel activities with differential manners. The aim of this study was to examine whether ginsenoside $Rg_3$ isomers also show differential effects on swine coronary artery contractionresponses induced by high $K^+$, serotonin (5-HT) or acetylcholine. Treatment of 20(S)- but not 20(R)-ginsenoside $Rg_3$ caused a concentration-dependent relaxation of coronary artery contracted by 25mM KCI. 20(S)- and 20(R)-ginsenoside $Rg_3$ induced significant relaxations of coronary artery contraction induced by 5-HT $(3{\mu}M)$ in the presence of endothelium with concentration-dependent manner and, also in the absence of endothelium only 20(S)-ginsenoside $Rg_3$ induced a strong Inhibition of coronary artery contraction induced by 5-HT in a concentration-dependent manner. 20(S)-ginsenoside $Rg_3$ caused relaxation of coronary artery in the absence and presence of endothelium. In contrast, treatment of 20(S)- and 20(R)-ginsenoside $Rg_3\;(100{\mu}M)$ did not show significant inhibition of coronary artery contraction induced by acetylcholine $(0.01\;to\;30{\mu}M)$ in the presence of endothelium, whereas both isomers caused significant inhibition of coronary artery contraction induced by acetylcholine $(0.01\;to\;30{\mu}M)$ in the absence of endothelium in a concentration-dependent manner. These findings indicate that 20(S)-or 20(R)-ginsenoside $Rg_3$ exhibits differential relaxation eff3cts of swine coronary artery contractions caused by high $K^+$, acetylcholine, and 5-HT treatment and that this differential vasorelaxing effects of ginsenoside $Rg_3$ isomers also might be dependent on endothelium.

• The Korea Journal of Herbology
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• v.25 no.4
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• pp.17-21
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• 2010

Objectives : The aim of this study was to evaluate the differential mechnism of vasodilation of alcohol steamed Rhei Tangutici Radix et Rhizoma. (ART) and Rhei Tangutici Radix et Rhizoma. (RT) in rat thoracic aorta. Methods : Rat aortic ring preparations were mounted in organ baths with oxygenated (95% $O_2$-5% $CO_2$) Krebs-Ringer bicarbonate solutions at $37{\pm}0.5^{\circ}C$ and subjected to contractions or relaxations. Results : ART exerted vasorelaxation on phenylephrine(PE)-induced contraction in a dose dependent manner. Vasorelaxation effects of ART and RT were endothelium-independent. In the $Ca^{2+}$-free high KCl (60 mM) baths, the contraction of aortic rings induced by accumulative addition of $Ca^{2+}$ (0.3-10.0 mM) was significantly reduced by pre-treatment with both ART and RT for 10 min. The magnitude of vasodilatation was biggerin ART. Moreover, verapamil ($0.001{\mu}M$) and diltiazem ($10{\mu}M$), voltage operative $Ca^{2+}$channel blockers, attenuated the relaxation effect of ART but not that of RT. In the absence of extracellular $Ca^{2+}$, pre-incubation of the aortic rings with RT ($1.0mg/m{\ell}$) significantly reduced the contraction caused by PE but not that of ART. $K^+$ channel inhibitors such as glibenclamide (Gli, $10^{-5}M$), tetraethylammonium (TEA, 1 mM) and 4-aminopyridine (4-AP, 0.2 mM) significantly reduced the ART's vasorelaxation efficacy, but not that of RT. However, the relaxation effects of ART and RT were not inhibited by pre-treatment with indomethacin ($10^{-5}M$), and atropine ($10^{-6}M$). Conclusions : These results suggest that the endothelium-independent relaxation is due to inhibition of $Ca^{2+}$ influx via the suppression of $Ca^{2+}$ release from intracelluar store in RT but via both voltage operative $Ca^{2+}$channel blockage and $K^+$ channel activation in ART.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.1
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• pp.37-42
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• 2012

The aim of the present study was to elucidate the direct effects of melatonin on bladder activity and to determine the mechanisms responsible for the detrusor activity of melatonin in the isolated rat bladder. We evaluated the effects of melatonin on the contractions induced by phenylephrine (PE), acetylcholine (ACh), bethanechol (BCh), KCl, and electrical field stimulation (EFS) in 20 detrusor smooth muscle samples from Sprague-Dawley rats. To determine the mechanisms underlying the inhibitory responses to melatonin, melatonin-pretreated muscle strips were exposed to a calcium channel antagonist (verapamil), three potassium channel blockers [tetraethyl ammonium (TEA), 4-aminopyridine (4-AP), and glibenclamide], a direct voltage-dependent calcium channel opener (Bay K 8644), and a specific calcium/calmodulin-dependent kinase II (CaMKII) inhibitor (KN-93). Melatonin pretreatment ($10^{-8}{\sim}10^{-6}M$) decreased the contractile responses induced by PE ($10^{-9}{\sim}10^{-4}M$) and Ach ($10^{-9}{\sim}10^{-4}M$) in a dose-dependent manner. Melatonin ($10^{-7}M$) also blocked contraction induced by high KCl ($[KCl]_{ECF}$; 35 mM, 70 mM, 105 mM, and 140 mM) and EFS. Melatonin ($10^{-7}M$) potentiated the relaxation response of the strips by verapamil, but other potassium channel blockers did not change melatonin activity. Melatonin pretreatment significantly decreased contractile responses induced by Bay K 8644 ($10^{-11}{\sim}10^{-7}M$). KN-93 enhanced melatonin-induced relaxation. The present results suggest that melatonin can inhibit bladder smooth muscle contraction through a voltage-dependent, calcium-antagonistic mechanism and through the inhibition of the calmodulin/CaMKII system.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.6
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• pp.141-148
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• 2005

Simplification of 3D models is becoming necessary with popularity of 3D graphics over mobile or the internet channels with limited channel capacity. Surfaces of a 3D model are usually approximated by a series of triangular meshes, and vertex contraction method is employed widely to minimize the deviation from the original model. Determination of the best position after contraction depends on the calculation of simplification error. We propose a new measure for computing the error so that the simplified model represents the original faithfully. We demonstrate the improved results with real 3D models.