• Journal of Yeungnam Medical Science
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• v.8 no.2
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• pp.95-105
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• 1991

This study was designed to investigate the effect of GABA and related substances on the spontaneous contraction of rat small intestine. The rats(Sprague-Dawley), weighing 200-250g, were sacrificed by cervical dislocation, and the small intestine was isolated. Longitudinal muscle strips from duodenum, jejunum and ileum were suspended in Biancani's isolated muscle chambers and myographied isometrically. GABA and muscimol, a GABA A receptor agonist relaxed the duodenum and jejunum significantly, but baclofen-induced relaxation in those muscle strips was negligible. The effectiveness of GABA and muscimol in various regions were the greatest on duodenum, and greater on jejunum than on ileum The effect of GABA and muscimol was antagonized by bicuculline, a compeptitive GABA A receptor antagonist and picrotoxin, a noncomptitive GABA A receptor antagonist. Duodenal relaxation induced by GABA and muscimol was unaffected by hexamethonium, but was prevented by tetrodotoxin. These results suggest that GABA inhibit the contractility of smooth muscle with distinct regional difference of efficacy, and the site of inhibitory action is the GABA A receptor existing at the presynaptic membrane of postganglionic excitatory nerves.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 2002.05a
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• pp.137-137
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• 2002

Several epidemiologidal studies suggested that arsenic exposure was strongly correlated with the development of cardiovascular disease such as hypertension. In order to examine whether arsenic affects vasomotor tone in blood vessels, we investigated the effect of arsenic on agonist-induced vasorelaxation using the isolated rat aortic ring in in vitro organ bath system. Treatment with arsenite inhibited acetylcholine-induced relaxation of aortic rings in a concentration- dependent manner. The inhibitory effects by arsenic were also observed in the relaxation induced by sodium nitroprusside, a NO-donor. Consistent with these findings, the cGMP levels stimulated by acetylcholine in blood vessels were reduced significantly by arsenite treatment. In addition, higher concentration of arsenite decreased the relaxation by 8-Br-cGMP, a cGMP analog, in aortic rings without endothelium. These in vitro results indicated that arsenite that arsenite was capable of suppressing acetylcholine-induced relaxation in blood vessels by inhibiting production of nitric oxide in endothelial cells and by impairing the relaxation machinary in smooth muscle cells. In vivo studies revealed that the reduction of blood pressure by acetylcholine infusion was signigicantly suppressed after arsenite was administered intravenously to rate. These data suggest that vasomotor tone impaired by arsenite exposure may be one of the contrbuting factors in development of cardiovascular disease.

• Journal of Ginseng Research
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• v.17 no.2
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• pp.109-113
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• 1993

The effects of ginseng total saponins (GTS) on the action of U-50,488H, a $textsc{k}$-opioid receptor agonist, on the electrically induced twitch responses of mouse vats deferens were studied. U-50,488H ($10^9$~$10^{-5}$M) inhibited the twitch contractions in a dose-dependent manner, which were caused by adenosine 5'-triphosphate (ATP) released from the stimulated sympathetic nerve, and this effect was antagonized by naloxone ($10^6$ M). GTS, which itself induced the inhibition of the twitch contractions, acted additively to U-50,488H, GTS and U-50,488H had no effect on the tension of the unstimulated organs. The contractions elicited by ATP were not affected by U-50,488H, but inhibited by GTS. These results suggest that U-50,488H suppressed the twitch contractions by the inhibition of neurotransmitter release from presynaptic nerve terminals via action on opioid receptor, but G75, by inhibiting the action of the neurotransmitter on the smooth muscle.

• Journal of Ginseng Research
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• v.21 no.2
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• pp.125-132
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• 1997

Our previous study showed that in vivo treatment of spontaneously hypertensive rats (SHR) with protopanaxatriol ginsenosides (PPT) reduces the blood pressure and inhibits the con- tractions induced by endothelium-derived contracting factor (prostaglandin endoperoxide ($PGH_2$) and superoxide anion) in aorta isolated from SHR. The aim of the present study is to examine whether PPT improves endothelial functions in the isolated thoracic aorta of SHR in vitro. Treatments of aortic rings with PPT, purified ginsenoside $Rg_1$ ($Rg_1$) or indomethacin normalized endotheliuln-dependent relaxation to acetylcholine, but not with protopanaxadiol ginsenosides (PPD) and purified ginsenoside Rb1 (Rb1). The effects of PPT were dose-dependent. PGH,- and oxygen free radical-inducted contractions in rat aorta without endothelium were inhibited by PPT or $Rg_1$, but not by PPD or $Rb_1$. Contractions induced by PGF2$\alpha$, U-46619, a stable thromboxane A2 agonist or KCI (60 mM) were not inhibited by PPT, $Rg_1$ or $Rb_1$. These findings demonstrate that PPT but not PPD scavenges the oxygen-derived free radicals and/or antagonize the effects of $PGH_2$ in the vascular smooth muscle and may explain the hypotensive effect of ginseng in the SHR.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.670-677
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• 2011

This study is to estimate the joint torques without torque sensor using the EMG (Electromyogram) signal of agonist/antagonist muscle with Neural Network Back Propagation Algorithm during the elbow motion. Command Signal can be guessed by EMG signal. But it cannot calculate the joint torque. There are many kinds of field utilizing Back Propagation Learning Method. It is generally used as a virtual sensor estimated physical information in the system functioning through the sensor. In this study applied the algorithm to obtain the virtual senor values estimated joint torque. During various elbow movement (Biceps isometric contraction, Biceps/Triceps Concentric Contraction (isotonic), Biceps/Triceps Concentric Contraction/Eccentric Contraction (isokinetic)), exact joint torque was measured by KINCOM equipment. It is input to the (BP)algorithm with EMG signal simultaneously and have trained in a variety of situations. As a result, Only using the EMG sensor, this study distinguished a variety of elbow motion and verified a virtual torque value which is approximately(about 90%) the same as joint torque measured by KINCOM equipment.

• YAKHAK HOEJI
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• v.55 no.2
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• pp.138-144
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• 2011

The aim of present study was to investigate the possible influence and related mechanism of resveratrol on U-46619 (high concentration)-induced vasoconstriction. Agonist-induced vascular smooth muscle contractions involve the activation of thick or thin filament pathway. However, there are no reports addressing the question whether this pathway is involved in resveratrol-induced relaxation in rat aortae contracted with high U-46619. We hypothesized that MEK or Rho-kinase inhibition plays a role in vascular relaxation evoked by resveratrol in rat aortae. Endothelium-denuded arterial rings from male Sprague-Dawley rats were used and isometric contractions were recorded using a computerized data acquisition system. Resveratrol fully inhibited U-46619 in low concentration-induced contraction regardless of endothelial function. However, resveratrol partially decreased U-46619 in high concentration-induced contraction regardless of endothelial function. Interestingly, only in U-46619 (high concentration)-induced contraction, no significant decrease was observed in phospho-ERK1/2 levels and slight decrease in phospho-MYPT1 levels suggesting that additional pathways different from them or endothelial nitric oxide synthesis might be involved in the vasorelaxation. In conclusion, in high U-46619-contracted rat aortae, resveratrol showed relaxation response regardless of endothelial function significantly but slightly decreasing MYPT1 phosphorylation rather than ERK1/2 phosphorylation.

• Proceedings of the Ginseng society Conference
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• 1998.06a
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• pp.182-189
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• 1998

Administration of ginsenosides, a mixture of saponin extracted from Panax ginseng, decreased blood pressure in rat. Previous studies have shown that ginsenosides caused endothelium-dependent relaxation, which was associated with the formation of cyclic GMP, suggested that ginsenosides caused release of nitric oxide (NO) from the vascular endothelium. The aim of the present study was to characterize the endothelium-independent relaxation to ginsenosides in the isolated rat aorta. Ginsenosides caused a concentration-dependent relaxation of rat aortic rings without endothelium constricted with 25 mM KCI but affected only minimally those constricted with 60 mM KCI. Ginsenoside Rg3 (Rg3) was a more potent vasorelaxing agonist than total ginsenoside mixture and also the ginsenoside PPT and PPD groups. Relaxation to ginsenosides were markedly reduced by TEA, but not by glibenclamide. Rg3 significantly inhibited Cal'-induced concentration-contraction curves and the "50a2'influx in aortic rings incubated in 25 mM KCI whereas those responses were not affected in 60 mM KCI. Rg3 caused efflux of $"Rb in aortic rings that was inhibited by tetraethy- lammonium (TEA), an inhibitor of Ca"-dependent K'channels, but not by glibenclamide, an inhibitor of AfP-dependent K'channels. These findings indicate that ginsenosides may induce vasorelaxation via activation of Ca2'-dependent K'channels resulting in hyperpolarization of the vas- cular smooth muscle with subsequent inhibition of the opening of voltage-dependent Caf'channels. These effects could contribute to explain the red ginseng-associated vasodilation and the beneficial effect on the cardiovascular system.

• PNF and Movement
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• v.6 no.1
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• pp.27-32
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• 2008

Purpose : The purpose of this study is to review of effect of the PNF application for improvement of the basic physical fitness in the elderly. Methods : By using internet, we research the PubMed, Science Direct, KISS, DBpia and the article on the effect of PNF. We selected the article between 1970 and 2007. Key words were PNF, Exercise, Elderly. Results : PNF refers to any of several post-isometric relaxation stretching techniques in which a muscle group is passively stretched, then contracts isometrically against resistance while in the stretched position, and then is passively stretched again through the resulting increased range of motion. Most PNF techniques employ isometric agonist contraction/relaxation where the stretched muscles are contracted isometrically and then relaxed. The most common PNF techniques are CR, HR, CRAC, HR-AC, AC. PNF exercise effected on the muscular strength and flexibility and balance and ROM in the elderly. Conclusion : PNF is a safety and effective exercise to improve the muscular strength and flexibility and balance and ROM in the elderly. Therefore, we suggest that PNF need to generalize for the elderly.

• Korean Journal of Applied Biomechanics
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• v.26 no.4
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• pp.421-426
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• 2016

Objective: The purpose of this study was to investigate how different levels of compression exerted on the femoral region (known as the power zone) by coated fabric influences the activation and anaerobic capacity of the rectus femoris. Method: Three different levels of compression on the rectus femoris of the participants, namely 0% (normal condition), 9% (downsize), and 18% (downsize), were tested. The material of the fabric used in this study was nonfunctional polyurethane. Surface electromyography test was used to investigate the activation of the rectus femoris, while the isokinetic test (Cybex, $60^{\circ}/sec$) and Wingate test were used to investigate the maximum anaerobic power. Results: The different compression levels (0%, 9%, and 18%) did not improve the strength and anaerobic capacity of the knee extensor. However, knee flexor interfered with activation of the biceps femoris, which is an agonist for flexion, during 18% compression. Conclusion: Compression garments might improve the stretch shortening cycle effect at the time of eccentric contraction and during transition from eccentric to concentric contraction. Therefore, future studies are required to further investigate these findings.

• International Journal of Oral Biology
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• v.44 no.2
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• pp.50-54
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• 2019

Melatonin is a neurotransmitter that modulates various physiological phenomena including regulation and maintenance of the circadian rhythm. Nicotinic acetylcholine receptors (nAChRs) play an important role in oral functions including orofacial muscle contraction, salivary secretion, and tooth development. However, knowledge regarding physiological crosstalk between melatonin and nAChRs is limited. In the present study, the melatonin-mediated modulation of nAChR functions using bovine adrenal chromaffin cells, a representative model for the study of nAChRs, was investigated. Melatonin inhibited the nicotinic agonist dimethylphenylpiperazinium (DMPP) iodide-induced cytosolic free $Ca^{2+}$ concentration ($[Ca^{2+}]_i$) increase and norepinephrine secretion in a concentration-dependent manner. The inhibitory effect of melatonin on the DMPP-induced $[Ca^{2+}]_i$ increase was observed when the melatonin treatment was performed simultaneously with DMPP. The results indicate that melatonin inhibits nAChR functions in both peripheral and central nervous systems.