• Biomolecules & Therapeutics
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• 제16권3호
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• pp.249-254
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• 2008

The present study was undertaken to determine whether hypoxia influences on the agonist-induced vascular smooth muscle contraction and, if so, to investigate the related mechanism. The measurement of isometric contractions using a computerized data acquisition system was combined with molecular experiments. Hypoxia significantly inhibited fluoride-induced contraction regardless of endothelial function, but there was no relaxation on thromboxane $A_2$ mimetic U-46619-induced contraction suggesting that other pathway such as $Ca^{2+}$ entry or thin filament regulation was not affected. In addition, hypoxia significantly decreased fluoride-induced increase of phospho-myosin-targeting subunit of myosin light chain phosphatase (pMYPT1). Interestingly, hypoxia didn't inhibit significantly phenylephrine-induced contraction suggesting that myosin light chain kinase (MLCK) activity or thin filament regulation is less important on the hypoxia-induced vasorelaxation in the denuded muscle than Rho-kinase activity. In conclusion, this study provides the evidence and possible related mechanism concerning the vasodilation effect of hypoxia on the agonist-specific contraction in rat aortic rings regardless of endothelial function.

• Biomolecules & Therapeutics
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• 제20권3호
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• pp.352-356
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• 2012

The present study was undertaken to determine whether ethanol influences on the agonist-induced vascular smooth muscle contraction and, if so, to investigate the related mechanism. The measurement of isometric contractions using a computerized data acquisition system was combined with molecular experiments. Ethanol significantly inhibited thromboxane $A_2$ mimetic-induced contraction with intact endothelial function, but there was no relaxation on thromboxane $A_2$ mimetic U-46619-induced contraction irrespective of endothelium suggesting that the pathway such as Rho-kinase activation, $Ca^{2+}$ entry or thin filament regulation was not affected. In addition, ethanol didn't decrease thromboxane $A_2$ mimetic-induced increase of phospho-myosin phosphatase targeting subunit protein 1 (pMYPT1) or pERK1/2. Interestingly, ethanol didn't inhibit significantly phorbol ester-induced contraction in denuded muscles suggesting that thin filament regulation is less important on the ethanol-induced regulation in the muscle than endothelial NO synthesis. In conclusion, this study provides the evidence and possible related mechanism concerning the effect of ethanol on the agonist-dependent contraction in rat aortic rings with regard to endothelial function.

• 대한수의학회지
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• 제36권1호
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• pp.83-91
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• 1996

Activation of $K^+$ channels induces relaxation of smooth muscles by reducing electrical excitability and cytosolic free $Ca^{2+}$ level. ${\beta}$-adrenergic agonist isoproterenol is known to induce relaxation of the uterine smooth muscle by membrane hyperpolarization and $K^+$ efflux. Recently it is suggested that the activity of $Ca^{2+}$-activated $K^+$ channel was increased by isoproterenol in the uterine myocytes isolated from myometrium of the pregnant rat. However, the type of $K^+$ channel mediating the relaxant effect of isopreterenol in the tissue level has not yet studied. In this work, we investigated the type of $K^+$ channels involved in the isoproterenol-induced relaxation of uterine smooth muscle by measuring the integrated insometric tension of the estrogen-treated isolated nonpregnant rat uterus. Contraction of uterine tissue was induced by oxytocin (0.2nM, 2~3 contractions/min) or high KCl(20~80mM). The result are as follows : 1. Isoproterenol($10^{-10}{\sim}10^{-4}M$) inhibited oxytocin-induced contraction of isolated rat uterus($EC_{50}=1.17{\times}10^{-10}M$). 2. Isoproterenol($10^{-10}{\sim}10^{-4}M$) effectively inhibited uterine contraction induced by low KCl(20~40mM) but little those induced by high KCl(60~80mM). 3. Relaxant effect of isoproterenol($10^{-10}{\sim}10^{-4}M$) on 0.2nM oxytocin-induced contraction was effectively reduced by 4-aminopyridine(3, 10mM) but little by TEA(10~30mM), $Ba^{2+}$($1{\sim}30{\mu}M$) and glibenclamide($100{\mu}M$). Our data suggest that the relaxant effect of isoproterenol is mediated by the $K^+$ channel(s) which can be blocked by 4-aminopyridine.

• 대한약리학회지
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• 제24권2호
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• pp.189-195
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• 1988

인체 정관 평활근에서 각종 자율신경전달체 수용체의 유무를 조사하고 benzodiazepine계의 진정-항불안제인 diazepam이 평활근 운동성에 미치는 작용을 관찰하기 위하여, 32내지 45세의 건강한 지원자로부터 정관절편을 얻었다. 정관 절제술은 국소마취하에 시행되었고, 정관절편의 수축력 측정은 등장성장력측정기에 의하였다. 적출장기실험조 내에서 정관절편의 자율수축은 관찰되지 않았으나, norepinephrine에 대한 반응성은 $33^{\circ}C$에서 가장 예민하였던 바, 이 norepinephrine에 의한 농도의존적 수축력증가작용은 알파-아드레날린성 차단제인 phentolamine에 의해 억제되었다. 또 인체 정관절편은 본 실험의 조건하에서 isoproterenol 의하여 수축하였고, 이 수축작용은 베타-아드레날린성 차단제인 propranolol 의하여 완전히 제거되었다. 동시에 인체 정관절편은 acetylcholine에의해서도 비교적 강하게 수축하였고, 이 수축작용은 콜린성 무스카린성 차단제인 atropine에 의하여 완전히 억제되었다. Diazepam은 norepinephrine에 의한 수축을농도 의존적으로 억 제 하였다. 이상의 결과를 종합하면, 인체 정관 평활근은 체온보다 낮은 $33^{\circ}C$에서 그 활동성이 가장 강하고, 자율신경에 대하여서는 아드레날린성 및 콜린성 수용체가 공존하고 있으며, diazepam은 그 수축력을 약화시킨다고 사료된다.

• The Korean Journal of Physiology and Pharmacology
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• 제4권1호
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• pp.33-40
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• 2000

This study was designed to clarify the mechanism of the inhibitory action of a nitric oxide (NO) donor, 3-morpholino-sydnonimine (SIN-1), on contraction, cytosolic $Ca^{2+}$ level $([Ca^{2+}]_i)$ and ionic currents in guinea-pig ileum. SIN-1 $(0.01{\sim}100\;{\mu}M)$ inhibited 25 mM KCl- or histamine $(10\;{\mu}M)-induced$ contraction in a concentration-dependent manner. SIN-1 reduced both the 25 mM KCl- and the histamine-stimulated increases in muscle tension in parallel with decreased $[Ca^{2+}]_i.$ Using the patch clamp technique with a holding potential of -60 mV, SIN-1 $(10\;{\mu}M)$ decreased peak Ba currents $(I_{Ba})$ by $30.9{\pm}5.4%$ (n=6) when voltage was stepped from -60 mV to +10 mV and this effect was blocked by ODQ $(1\;{\mu}M),$ a soluble guanylyl cyclase inhibitor. Cu/Zn SOD (100 U/ml), the free radical scavenger, had little effect on basal $I_{Ba},$ and SIN-1 $(10\;{\mu}M)$ inhibited peak $I_{Ba}$ by $32.4{\pm}5.8%$ (n=5) in the presence of Cu/Zn SOD. In a cell clamped at a holding-potential of -40 mV, application of $10\;{\mu}M$ histamine induced an inward current. The histamine-induced inward current was markedly and reversibly inhibited by $10\;{\mu}M$ SIN-1, and this effect was abolished by ODQ $(1\;{\mu}M).$ In addition, SIN-1 markedly increased the depolarization-activated outward $K^+$ currents in the all potential ranges. We concluded that SIN-1 inhibits smooth muscle contraction mainly by decreasing $[Ca^{2+}]_i$ resulted from the inhibition of L-type $Ca^{2+}$ channels and the inhibition of nonselective cation currents and/or by the activation of $K^+$ currents via a cGMP-dependent pathway.

• 대한수의학회지
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• 제43권3호
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• pp.415-421
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• 2003

It is now generally accepted that acupuncture is effective in diarrhea caused by bacterial infection. However, its effect on the intestinal smooth muscle dysfunction is not clear. Therefore, we investigated the effect of acupuncture therapy at Jiao-chao (GV-1) on the intestinal muscle dysfunction in weaning piglets orally infected by Escherichia coli. The animals are divided into four groups; 1) E. coli + no-treatment, 2) E. coli + antibiotic, 3) E. coli + acupuncture, 4) normal group. In the three E. coli infected groups, low frequency electrical field stimulation (EFS, 1 Hz) provoked triphasic responses composed of initial relaxation followed by on-contraction and off-contraction. While in the normal group, EFS (1Hz) induced biphasic responses composed of relaxation during the stimulation and off-contraction. At the high frequency (16Hz) EFS, both on-contraction and off-contraction of the E. coli + antibiotic, E. coli + acupuncture and the normal group were larger than those of the E. coli + no-treatment group. In the non-adrenergic non-cholinergic (NANC) condition, only biphasic responses occurred to EFS in all experimental groups and the off-contraction of E. coli + antibiotic, E. coli + acupuncture and the normal group were larger than those of the E. coli + no-treatment group. The response to carbachol of those three groups was also significantly greater than that of the E. coli + no-treatment group. These results suggest that acupuncture is as effective as antibiotic in the dysfunction of colonic circular muscle caused by E. coli infection. The maintenance of contractile neuromuscular transmission seems to be involved in the mechanism of the acupuncture effects on diarrhea.

• 대한약리학회지
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• 제24권2호
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• pp.197-201
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• 1988

본 연구에서는 세포내의 칼슘이온과 결합하여 형광을 발하는 형광색소 fura 2를 이용하여 세포내의 칼슘이은 농도를 측정함과 동시에 장력을 측정하였으며 이에 대한 카페인과 고농도의 칼륨의 영향을 정토하였다. 72.7 mM의 칼륨 이온은 장력과 세포내 칼슘이온농도에서 각각 지속적 인 증가를 보여주었으며, 20 mM의 카페인은 일과성의 빠른 세포내의 칼슘이은농도의 증가에 이어 감소를 보여주었으나 기본치 보다는 높았다. 그러나, 장력에 있어서는 카페인은 일과성의 증가에 이어 기본 장력보다 낮은 감소를 보여주었다. 한편 칼슘이온 제거 용액에서 칼륨이온은 세포내의 갈륨이온 농도도 장력도 증가 시키지 못하였으나 카페인은 일과성의 세포내의 칼륨이온 농도와 장책의 증가를 보여주었다. 이상과 결과로부터 rat 대동맥에서의 고농도의 칼륨이은에 의한 수축은 세포 딴으로 부터의 칼슘이온 유입에 의한 것이며 반면에 카페인에 의한 수축은 세포내의 칼슘이온저장부위로 부터의 칼슘이온 유리에 의한 것임을 시사한다. 또한, 카페인은 세포내의 수축 단백의 칼슘 이온에 대한 감수성을 저하시키는 듯하다.

• The Korean Journal of Physiology
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• 제21권2호
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• pp.259-272
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• 1987

This was study carried out to investigate the effect of calcium on spontaneous contraction and electrical activity induced by ethanol in gastric smooth muscle. After peeling off the mucous membrane from the isolated whole stomach of 102 cats, two kinds of small muscle preparations $(2.0{\times}0.2\;cm)$, one longitudinal and the other circular, were excised from the fundus, the corpus and the antrum portion of each whole stomach specimen. The isometric contraction of the small muscle preparation was measured in a cylinder-shaped chamber filled with Krebs-Ringer-dextrose solution (pH 7.4, temperature $36{\pm}0.5^{\circ}C$) bubbling with 5% $CO_2$ in $O_2$. A large muscle preparation $(5.0{\times}1.2\;cm)$ was excised from the anterior wall of the corpus-antrum portion of the same specimen in 72 of 102 cats. The gastric electrical activity (slow wave and spike potential) was monopolarly recorded by four capillary electrodes (Ag-AgCl), of which two were placed on the corpus and two on the antrum, in a muscle chamber filled with the same solution as described above. Changes in the amplitude of the contraction, frequency of the gastric slow wave and the production of the spike potential were observed after adding ethanol and/or under the treatments with verapamil, $CaCl_2$ and Ca-free Krebs-Ringer-dextrose solution. The results were as follows: 1) After adding ethanol, the spontaneous phasic contraction of the corpus was reduced dose-dependently (0.125-2.0%), which was totally abolished by higher concentrations (2.0-8.0%) of ethanol. 2) The corporal phasic contraction was also completely abolished by verapamil $(3{\times}10^{-5}\;M)$ or Ca-free Krebs-Ringer-dextrose solution. The contraction was increased by $CaCl_2\;(1.8{\times}10^{-3}\;M)$, but the inhibitory effect of ethanol on the contraction persisted even under the treatment with $CaCl_2$. 3) At higher concentrations, ethanol caused tonic contraction of both preparations from the fundus, the corpus and the antrum in a dose-dependent manner. The tonic contraction of the fundus produced by ethanol was not influenced by $CaCl_2$ or verapamil, whereas the tonic contraction was not produced by ethanol in tile Ca-free solution. 4) Frequency of gastric slow wave was decreased dose-dependently by the addition of ethanol (0.25-1.0%), and tile slow wave was not produced by higher concentration of ethanol (2.0%). 5) The frequency of slow wave was significantly reduced by verapamil only and the inhibitory influence of ethanol on the slow wave frequency was reinforced by verapamil. 6) The treatment of $CaCl_2$ increased significantly the slow wave frequency, and attenuated the inhibitory effect of ethanol on the frequency. It is therefore suggested that ethanol regulates the phasic contraction and the production of slow wave by interfering with the transport of calcium in the stomach muscle of the cat.

• Journal of Korean Neurosurgical Society
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• 제38권5호
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• pp.375-379
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• 2005

Objective : Papaverine has been used in treating vasospasm following subarachnoid hemorrhage[SAH]. However, its action mechanism for cerebral vascular relaxation is not clear. Potassium channels are closely related to the contraction and relaxation of cerebral smooth muscle. Therefore, to identify the role of potassium and calcium channels in papaverine-induced vascular relaxation, we examine the effect of papaverine on potassium channels in freshly isolated smooth muscle cells from rat basilar artery. Methods : The isolation of rat basilar smooth muscle cells was performed by special techniques. The whole cell currents were recorded by whole cell patch clamp technique in freshly isolated smooth muscle cells from rat basilar artery. Papaverine was added to the bath solution. Results : Papaverine of $100{\mu}M$ into bath solution increased the amplitude of the outward $K^+$ current which was completely blocked by BKCa[large conductance calcium dependent potassium channels]blocker, IBX[iberiotoxin], and calcium chealator, BAPTA[l,2-bis[o-aminophenoxy]ethane-N,N,N',N'-tetraacetic acid], in whole cell mode. Conclusion : These results strongly suggest that potassium channels may play roles in papaverine-induced vascular relaxation in rat basilar artery.

• 대한수의학회지
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• 제39권3호
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• pp.472-477
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• 1999

To elucidate the action of the cholinergic and adrenergic nerve on isolated gastric fundus smooth muscle of rabbit, the effects of electrical transmural stimulation were investigated in the presence of atropine, cholinergic receptor blocker; phentolamine, nonselective ${\alpha}$-adrenergic receptor blocker; propranolol, nonselective ${\beta}$-adrenergic receptor blocker and L-arginine from the isometric contraction of physiological recording system. 1. The contractile response induced by electrical transmural stimulation was increased as the frequency(1~32Hz)-dependent manner on the isolated gastric fundus smooth muscle. 2. The contractile response induced by electrical transmural stimulation was markedly inhibited by the pretreatment of atropine($1{\mu}M$). 3. The contractile response induecd by electrical transmutal stimulation was inhibited by the pretreatment of phentolamine($1{\mu}M$). 4. The relaxative response induced by electrical transmural stimulation on presence of atropine ($1{\mu}M$) was inhibited by the pretreatment of propranolol($1{\mu}M$). 5. The relaxative responses on precontraction induced by histamine($10{\mu}M$) with guanethidine ($50{\mu}M$) and atropine($1{\mu}M$) by electrical transmural stimulation were increased by L-arginine (1mM). These findings suggest that it was the excitatory action of cholinergic and ${\alpha}$-adrenergic nerve, and the inhibitory action of ${\beta}$-adrenergic nerve and nonadrenergic noncholinergic nerve on the isolated gastric fundus smooth muscle of rabbit.