• 제목/요약/키워드: Phasic contraction

검색결과 42건 처리시간 0.022초

Evaluation of Treatment Outcomes in Oromandibular Dystonia Using Surface Electromyography: A Case Series

  • Im, Yeong-Gwan;Kim, Jae-Hyung;Kim, Byung-Gook
    • Journal of Oral Medicine and Pain
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    • 제46권4호
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    • pp.143-149
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    • 2021
  • Purpose: Oromandibular dystonia is a neurological disorder that affects the jaw and lower face muscles, often resulting in abnormal repetitive movement of the jaw and perioral structures. The purpose of this study was to assess the effectiveness of surface electromyography (EMG) in evaluating the treatment outcome of oromandibular dystonia. Methods: Based on a retrospective review of medical records, we analyzed the data of four patients who received medication or botulinum toxin injection, as well as surface EMG of the jaw muscles before and after treatment. We assessed the patients' clinical characteristics and the results of surface EMG before and after treatment. Results: The case series included one female and three males, and the age range was 65-78 years. Based on the clinical features, two subjects were classified as jaw deviation and the remaining two were as jaw closing. Dystonic patterns revealed by surface EMG varied, including phasic, tonic, and mixed contraction patterns. EMG amplitude after treatment was lower than pre-treatment value in all four subjects, suggesting improved clinical signs and symptoms. One subject who received clonazepam and another who received botulinum toxin injection showed a remarkable reduction in EMG amplitude within a normal range. Conclusions: Surface EMG can be used to effective evaluate treatment outcomes in patients with oromandibular dystonia. It could be considered as an adjunctive diagnostic tool in managing patients with dystonia.

적출 심근의 칼륨경축에 대한 칼슘이온 효과 (Effect of $Ca^{++}$ on High K-induced Contracture of Isolated Frog Ventricular Muscle)

  • 최윤백;김기환
    • The Korean Journal of Physiology
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    • 제20권1호
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    • pp.31-41
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    • 1986
  • The sufficient myoplasmic $Ca^{++}$ to react with the contractile proteins is necessary to induce contraction of a cardiac muscle. These $Ca^{++}$ for the production of muscle contraction are supplied from the three recognized $Ca^{++}$ sources; internal $Ca^{++}$ release via the sarcoplasmic reticulum(SR), $Ca^{++}$ influx through a gated Ca-channel in the membrane as a Isi, and $Ca^{++}$ transport by the mechanism of Na/ca exchange. However, it is still controversial which $Ca^{++}$ sources act as a main contributor for myoplasmic $Ca^{++}$, Therefore, this study was undertaken in order to examine the $Ca^{++}$ sources for the contraction of frog ventricle. There is evidence that the SR is sparse in frog ventricular fibers, and that T-tubules are absent. Isolated ventricular strips of frog, Rana nigromaculata, were used in this experiment. Isometric tension was recorded by force transducer, and membrane potentials of ventricular muscles were measured through the intracellular glass microelectrodes, which were filled with 3M KCI and had resistance of $30{\pm}50M{\Omega}$. All experiments were performed at room temperature in a tris·buffered Ringer solution which was aerated with 100% $O_2$. Isotonic high K, low Na solution was used to induce K-contracture, K-contracture appeared at the concentration of 20 to 30mM-KCI and was potentiated in parallel with the increase in KCI concentration. The contracture had two components: an initial rapid phasic and a subsequent slow tonic contractile responses. Membrane Potentials measured at normal Ringer solution(2.5mM KCI) was -90 to -100 mV, and decreased linearly as the KCI concentration increased; -55mV at 20mM.KCI, -45mV at 30 mM.KCI, -30 mY at 50 mM.KCI, and -12 mV at 100 mM.KCI. K-contracture was evoked firstly at the membrane potential of -45 mV. The contracture was potentiated by the increase of bathing extracellular $Ca^{++}$ concentration. However, in the absence of $Ca^{++}$ the contracture was almost not induced by 50 mM.KCI solution. Caffeine(20mM) in normal Ringer solution, which is known to release $Ca^{++}$ from SR without substantial effects on the $Ca^{++}$ fluxes across the surface membrane, did not affect membrane potential and also not initiate contracture, but the caffeine in 20 mM-KCI Ringer solution produced a contracture. Above results suggest that the main $Ca^{++}$ source for the K·contracture of frog ventricle is $Ca^{++}$ influx through the voltage-dependent Ca-channel, and that in the K-contracture at the concentration of 100 mM-KCI, the mechanism of Na/ca exchange also partly contributs, in addition to the $Ca^{++}$ influx.

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SSP 주파수 진폭변조가 Vasoactive Intestinal Peptide와 $\beta$-endorphin, cGMP에 미치는 영향 (Effects of frequency - amplitude electrical stimulation on sympathetic neurotransmitter and vasoactive intestinal peptide)

  • 최영덕;심규리;장문경
    • The Journal of Korean Physical Therapy
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    • 제14권4호
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    • pp.454-474
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    • 2002
  • Vasoactive intestinal peptide (VIP) is a very potent dilatator and a nonadrenergic, noncholinergic (NANC) neurotransmitter or neuromodulator in the peripheral and the central nervous systems. The mechanisms of action of VIP were examined in aortic circular and in uterine longitudinal smooth muscle strips of the rat. The effects of sympathetic neurotransmitter were investigated in gastric and aortic circular muscle strips of the mouse and the rat. The effects of silver spike point, SSP, low frequency electrical stimulations of VIP, sympathetic neurotransmitter and $\beta$-endorphin were examined in plasma, serum and 24h urine from the healthy volunteer. In gastric smooth muscle strips from the mouse, adrenergic neurotransmitter norepinephrine was inhibitory effected, followed by caused phasic and tonic contraction to the, muscrine receptor agonist carbachol and acetylcholine, respectively. In urine from the healthy volunteer, both norepinephrine and epinephrine were significantly decreased in continue type and low frequency (3 Hz) of SSP electrical stimulations. The contractile responses to S-HT in uterine longitudinal smooth muscle strips of the rats were completely decreased by a VIP 1 $\mu$M. The contractile responses to PGF2$\alpha$ were not decreased by a VIP. In plasma and serum from the healthy volunteer, both VIP and $\beta$-endorphin were significantly increased in continue type and low frequency (3 Hz) of SSP electrical stimulations. Therefore, this study demonstrate that VIP has the capacity to relax vascular or gastric smooth muscles in part by stimulating the generation of NO, and silver spike point low frequency electrical stimulation has the capacity both to decrease sympathetic neurotransmitters and to increase VIP, $\beta$-endorphin.

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마그네슘이온이 적출한 기니피그 대동맥평활근과 흰쥐 자궁평활근의 수축성에 미치는 효과에 관한 연구 (Effect of Magnesium on the Contractility of the Isolated Guinea-Pig Aortic and Rat Smooth Muscles)

  • 안혁;황상익
    • Journal of Chest Surgery
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    • 제23권3호
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    • pp.452-464
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    • 1990
  • It is well known that extracellular Calcium plays a very important role in several steps of smooth muscle excitability and contractility, and there have been many concerns about factors influencing the distribution of extracellular Ca++ and the Ca++ flux through the cell membrane of the smooth muscle. Based on the assumption that Mg++ may also play an important role in the excitation and contraction processes of the smooth muscle by taking part in affecting Ca++ distribution and flux, many researches are being performed about the exact role of Mg++, especially in the vascular smooth muscle. But yet the effect of Mg++ in the smooth muscle activity is not clarified, and moreover the mechanism of Mg++ action is almost completely unknown. Present study attempted to clarify the effect of Mg++ on the excitability and contractility in the multiunit and unitary smooth muscle, and the mechanism concerned in it. The preparations used were the guinea-pig aortic strip as the experimental material of the multiunit smooth muscle and the rat uterine strip as the one of the unitary smooth muscle. The tissues were isolated from the sacrificed animal and were prepared for recording the isometric contraction. The effects of Mg++ and Ca++ were examined on the electrically driven or spontaneous contraction of the preparations. And the effects of these ions were also studied on the K+ or norepinephrine contracture. All experiments were performed in tris-buffered Tyrode solution which was aerated with 100% 02 and kept at 35oC. The results obtained were as follows: 1] Mg++ suppressed the phasic contraction induced by electrical field stimulation dose-dependently in the guinea-pig aortic strip, while the high concentration of Ca++ never recovered the decreased tension. These phenomena were not changed by the a - or b - adrenergic blocker. 2]Mg++ played the suppressing effect on the low concentration [20 and 40 mM] of K+-contracture in the aortic muscle, but the effect was not shown in the case of 100mM K+-contracture. 3] Mg++ also suppressed the contracture induced by norepinephrine in the aortic preparation. And the effect of Mg++ was most prominent in the contracture by the lowest [10 mM] concentration of norepinephrine. 4] In both the spontaneous and electrically driven contractions of the uterine strip, Mg++ decreased the amplitude of peak tension, and by the high concentration of Ca++ the amplitude of tension was recovered unlike the aortic muscle. 5] The frequency of the uterine spontaneous contraction increased as the [Ca++] / [Mg++] ratio increased up to 2, but the frequency decreased above this level. 6] Mg++ decreased the tension of the low[20 and 40mM] K+-contracture in the uterine smooth muscle, but the effect did not appear in the 100mM K+-contracture. From the above results, the following conclusion could be made. 1] Mg++ seems to suppress the contractility directly by acting on the smooth muscle itself, besides through the indirect action on the nerve terminal, in both the aortic and uterine smooth muscles. 2] The fact that the depressant effect of Mg++ on the K+-contracture is in inverse proportion to an increase of K+ concentration appears resulted from the extent of the opening state of the Ca++ channel. 3] Mg++ may play a depressant role on both the potential dependent and the receptor-operated Ca++ channels. 4] The relationship between the actions of Mg++ and Ca++ seems to be competitive in uterine muscle and non-competitive in aortic strip.

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흰쥐 기관평활근에 대한 GS 386의 칼슘억제 및 포스포디에스테라제 억제 작용 (Calcium Channel Blocking and Phosphodiesterase Inhibitory Action of GS386, a Dihydroisoquinoline Derivative, in Isolated Rat Trachea)

  • 장기철;이회영;강영진;구의본
    • 대한약리학회지
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    • 제32권3호
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    • pp.373-380
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    • 1996
  • 최근 본 연구실에서는 GS 386인 1-(4'-methoxybenzyl)-6,7-dimethoxy-3,4-dihydroisoquinoline이 적출된 토끼의 심방세포에서 $Ca^{++}$ 채널의 운동성 변화없이 $Ca^{++}$ 채널이 열릴 가능성을 줄임으로써 $Ca^{++}$ 전류의 증폭을 억제한다고 보고하였다. 이번 연구에서는 적출된 쥐의 기관지를 사용하여 GS 386의 작용기전에 대해 연구하였다. GS386은 carbachol $(0.3{\mu}M)$과 높은 농도의 $K^+$ (65.4mM)에 의해 수축된 쥐의 기관지를 용량-의존적으로 이완시켰으며 이때 $IC_{50}$는 5.24와 $5.67\;{\mu}M$이었다. verapamil은 carbachol에 의한 수축시 보다 높은 농도의 $K^+$에 의해 수축된 조직에 더욱 효과적으로 억제하였다. $Ca^{++}$이 없는 상태에서 $Ca^{++}$에 의한 수축은 GS386에 의해 억제되었다. 더욱이 높은 농도의 GS386$(100\;{\mu}M)$은 verapamil과는 다르게 carbachol뿐만 아니라 caffeine에 의한 위상성 수축을 억제 시키므로 GS386은 세포질내로 들어가 sarcoplasmic retuculum과 같은 근육 내부에 2차적인 영향을 나타내었다. 더군다나GS386은 verapamil에 의해 영향을 받지않는 (verapamil-insensitive component)이완을 보였고 쥐 기관지의 평활근에서 cAMP의 양을 증가 시켰다. 이러한 결과는 GS386의 작용기전이 $Ca^{++}$ 길항적인 작용 뿐만 아니라 posphodiesterase억제작용에 기인한다는 사실을 제시한다.

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한국산(韓國産) 사독(蛇毒)에 관(關)한 실험적(實驗的) 연구(硏究) (Experimental Studies on Korean Snake Venoms)

  • 김원준;안영수;김주덕;김세환;홍사석
    • 대한약리학회지
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    • 제12권2호
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    • pp.33-41
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    • 1976
  • Agkistrodon halys (Crotalidae) is the only species of poisonous snakes in Korea, and is divided into three subspecies; Agkistrodon bromhoffii brevicaudus, Agkistrodon calaginosus and Agkistrodon saxatilis. With the three venoms, the pharmacological actions on the cardiovascular system and intestine as well as some toxicological characteristics were studied. In addition, the precipitin test in an agar gel medium was employed for immunological comparison of the venoms and the sera of envenomed patients. The results obtained were as follows: Lyophilized venoms contained solids of $211{\sim}273mg/ml$, and LD50 to mice were 1.73 and 0.86 mg/kg in venoms of Agkistrodon bromhoffii brevicaudus obtained on July and October respectively, and 0.40 and 0.32 mg/kg in Agkistrodon calaginosus and the venoms of Agkistrodon saxatilis obtained on October was 2.29 mg/kg. Isoelectric focusing of lyophilized snake venoms showed 19 to 22 protein fractions and 2 to 3 isoamylase fractions. Acute irreversible hypotension was caused by the intravenous injection of large doses of venoms in rabbits and cats, but at the small doses, acute hypotension followed by slow recovery. Little changes of cardiac movements by the venom injection despite of marked hypotension were showed except bradycardia and arrhythmia prior the death. Also no changes on the isolated rabbit atria by the snake venoms were noted. The hypotensive effect of the snake venoms was prevented by the bilateral vagotomy or atropine pretreatment (1 mg/kg), but they did not affect when already the hypotension has undergone. In the isolated rabbit duodenum, small doses of venom increased the phasic movement, while large doses decreased after spastic contraction. With the injection of venoms in dog, strong contraction of gall-bladder was caused and it was not blocked by the pretreatment with phenoxybenzamine (10 mg/kg) or atropine (1.4 mg/kg). In the venoms of Agkistrodon bromhoffii brevicaudus and Agkistrodon calaginosus, at least 5 antigenic components were detected, and four of them were shared in common with each other. Polyvalent antivenin (Wyeth Lab. USA) had three common precipitating antibodies with the venom of Agkistrodon bromhoffii brevicaudus and Akistrodon calaginosus. In the serum of envenomed patients, no precipitating antibodies were seen to the venoms and little changes in serum protein, GOT and GPT were observed. In conclusion, the snake venoms obtained in Korea were highly toxic and caused chiefly the vascular collapse leading to death. This vascular collapse was resulted largely by cholinergic effects, and not cardiotoxin of venoms. In human, it is likely that precipitating antibodies to venom were not produced by an envenomed incidence to poisonous snakes.

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편마비 환자를 위한 근전도 유발 기능적 전기자극기의 개발과 이상적인 전극부착 위치 (Development of EMG-Triggered FES System and Optimal Electrode Location for Chronic Hemiplegic Patients)

  • 박병림;안상호;정호춘;진달복;김성곤;이상세;김영기
    • 대한의용생체공학회:의공학회지
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    • 제25권2호
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    • pp.151-156
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    • 2004
  • 편마비 환자에서 상지 기능을 효과적으로 회복시키기 위하여 근전도 유발 기능적 전기자극기 개발과 편마비 환자를 대상으로 손목, 수지신전 운동 시 가장 효과적으로 근수축을 감지 할 수 있는 위치와 전기 자극 시 가장 이상적인 손목, 수지 신전 운동이 일어나는 부위를 탐색하여 두 부과가 일치하는 이상적인 전극부착 위치를 설정하였다. 1) 전기자극 시스템으로 EMC 계측부, 정전류 회로부를 개발하고 프로그램으로는 근전도 유발 전기자극기와 Passive FES의 동작이 가능한 형태로 개발하였다 자극조건은 주파수 35 Hz, 펄스폭 150 ${\mu}\textrm{s}$, 비대칭적 이상성 파형을 선택하였다. 2) 상지 편마비 환자 15명을 대상으로 전완의 근위부 1/2부위를 12개의 영역으로 나눈 후 근위부의 외측으로부터 영역의 순서를 정하였다. 각 영역에서 환자의 손목을 신전 하였을 때 근전도 유발 자극기가 감지하는 활동전위의 진폭을 측정하였으며 가장 크게 감지된 영역은 4, 5 영역이었고, 전기자극을 시행하였을 때 손목과 수지부위가 신전 되는 모양이 이상적인 영역은 4, 5, 7, 8 영역이었다. 근전도 유발 전기자극을 시행하였을 때 근 수축을 감지하여 근전도 유발 전기자극이 일어나는 일련의 과정이 이상적인 영역은 해부학적으로 4, 5 영역이었다.

흰쥐의 적출 정관 수축성에 대한 ${\gamma}$-Aminobutyric Acid의 억제작용 (Inhibitory Effects of ${\gamma}$-Aminobutyric Acid on the Contractility of Isolated Rat Vas Deferens)

  • 안기영;권오철;하정희;이광윤;김원준
    • Journal of Yeungnam Medical Science
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    • 제9권2호
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    • pp.382-395
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    • 1992
  • GABA는 중추신경계의 대표적인 신경전달 물질로서 $GABA_A$수용체 또는 $GABA_B$수용체에 작용하여 진정 작용, 항 불안 작용, 및 근이완 작용을 하는 것으로 알려져 있다. 근래에는 말초조직에도 GABA가 존재하며 신경조정인자 혹은 신경전달인자로서 작용한다는 보고가 있다. 정관에 대한 자율신경 지배는 아드레날린성, 콜린성과 비콜린성 비아드레날린성 신경섬유들이 분포하고 있으나, 종 혹은 부위에 따라 이들 구성요소들의 수축성에 대한기여도가 다른 것으로 알려져 있다. 본 실험에서는 흰쥐의 전립선 부위 정관의 기본장력 및 전기장 유발 수축에 대한 교감 신경성, 부교감 신경성 및 퓨린성 효현제의 영향을 관찰하였으며, 정관의 흥분성 약물 및 전기장 유발 수축에 미치는 GABA 및 GABA 관련 약물의 영향을 관찰함으로서 정관의 수축운동에 대한 GABA의 작용기전을 규명해 보고자 흰쥐(Sprague-Dawley)의 전립선 부위 정관 절편을 적출 근편 실조에 현수하고, 등척성 장력을 측정하여 다음과 같은 결과를 얻었다. 1. GABA, muscimol 및 baclofen은 전기장자극(0.2 Hz, 1 msec, 80 V) 유발 수축을 농도 의존적으로 억제하였으며 그 효력은 GABA, baclofen 그리고 muscimol 순이었다. 2. GABA의 억제작용은 $GABA_B$ 수용체 길항제인 DAVA에 의하여 길항되었으나, $GABA_A$ 수용체 길항제인 bicuculline에 의해서는 길항되지 않았다. 3. Baclofen의 억제작용은 DAVA에 의하여 길항되었으나 muscimol의 억제작용은 bicuculline에 의해서는 길항되지 않았다. 4. Norepinephrine과 ATP는 농도 의존적으로 정관의 수축력을 증가 시켰으나 acetylcholine은 영향을 미치지 못하였다. 5. GABA, baclofen 및 muscimol은 정관의 기본 장력에는 영향을 미치지 않았으며, GABA는 norepinephrine과 ATP 유발 수축에는 영향을 주지 못하였다. 6. 적출 정관을 20초간 전기장 자극을 가하였을 때 ATP 수용체 탈감작제인 mATP를 전처치한 경우에는 FPC가 감소되었고, 신경원에서 catecholamine을 고갈시키는 reserpine을 전처치한 경우에는 STC가 감소되었다. 7. GABA는 mATP를 전처치한 군에서는 정관의 전기장 유발 수축에 영향을 주지 못하였으나, reserpine을 전처치한 군에서는 전기장 유발 수축을 억제하였다. 이상의 결과로 보아 흰쥐정관의 전립선 부위에는 아드레날린성 신경전달기전과 퓨린성 신경전달기전이 동시에 작용하고 있으며, GABA는 주로 신경원의 $GABA_B$ 수용체를 통하여 ATP의 유리를 억제하는 것으로 사료된다.

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흰쥐 적출 자궁의 수축 작용과 흰쥐 장관에 있어 칼륨에 의해 활성화되는 칼슘 채널에 대한 Cyclobuxine D의 영향 (Effects of Cyclobuxine D on Drug-Induced Contractions of the Isolated Rat Uterine Muscle and Potassium-Activated Calcium Channels in an Intestinal Smooth Muscle)

  • 권준택;이종화;박영현;조병현;최규홍;김유재;김종배;김정목;김천숙;차영덕;김영석
    • 대한약리학회지
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    • 제24권1호
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    • pp.103-109
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    • 1988
  • Buxus microphylla var. koreana Nakai에 존재 하는 steroidal alkaloid인 cyclobuxine D는 흰쥐에 있어 심박동수 감소 작용, 적출 개구리 심장에서 수축력 감소작용, 토끼 적출 장관에서 acetylcholine과 $Ba^{++}$.에 유발되는 수축에 대한 억제작용 등을 나타낸다고 보고되었다. 본 연구에서는 흰쥐 적출 자궁에서 acetylcholine, oxytocin과 $Ba^{++}$에서 의해 나타나는 수축 작용에 대한 cyclobuxine D의 영향을 관찰하였으며, 또 흰쥐 적출장관에서 칼륨에 의해 활성화되는 칼슘채널에 대한 cyclobuxine D의 작용을 관찰하였다. Cyclobuxine D는 흰쥐 적출 자궁에서 acetylcholine, oxytocin과 $Ba^{++}$에 의해 증가되는 peak tension과 duration을 용량적으로 현저히 억제하였다. Cyclobuxine D는 oxytocin보다 acetylcholine에 의해 나타나는 수축작용에 대해 강하게 작용했다. 흰쥐 적출 장관(ileum)을 Ca을 고갈시킨 Tyrode's 용액에 $40{\sim}50$분 담그고 $Na^+$ 대신 $K^+$로 대체시킨 용액에 10분간 담근 후 1.8 mM $CaCl_2$를 가했을 때 이중적인 근육수축작용이 나타난다(Phasic and tonic increase in tension). Cyclobuxine D $(6.2{\times}10^{-5}\;M)$은 이 두 components를 유의하게 억제하였으며 tonic component가 최대치에 도달했을 때 cyclobuxine D $(3.1{\times}10^{-4}\;M)$을 가하면 근육은 긴장도를 빨리 상실했다. 이 결과는 적출 장관에 있어 칼륨에 의해 활성화되는 칼슘 채널이 cyclobuxine D에 의해 차단되고 있음을 나타낸다. 이상의 결과에서 cyclobuxine D의 흰쥐 적출 자궁에 대한 수축 억제 작용은 voltage-dependent calcium channel 차단에 밀접한 관련이 있는 것으로 사려된다.

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결장뉴 전기활동도에 대한 Ouabain과 Vanadate의 작용 (Effects of Ouabain and Vanadate on the Spontaneous Contractions and Electrical Activity in Guinea-pig Taenia Coli)

  • 박종규;김기환;서인석
    • The Korean Journal of Physiology
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    • 제22권2호
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    • pp.189-206
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    • 1988
  • The effects of ouabain on the contractile and electrical activities were investigated in the isolated preparations of guinea-pig taenia coli, and compared with those of vanadate. Spontaneous contractions were recorded with force transducer, and electrical activites were measured by use of suction electrode, or single sucrose-gap technique. The contractions were induced by the electrical stimulation for 5 seconds every 1 minute with alternating current (60 Hz, 3.0 V/cm) through the platinum electrodes located in parallel with the long axis of the preparation. All experiments were performed in tris-buffered Tyrode solution which was aerated with $100%{\;}O_2$ and kept at $35^{\circ}C$. The results obtained were as follows: 1) Responses of spontaneous contractions to ouabain were concentration-dependent; $10^{-7}M$ ouabain caused a rise of basal tone. Above the concentration of $10^{-6}M$ ouabain, an initial increase followed by a decrease in tension was observed. 2) A continuous spike discharge was induced by the administration of $10^{-7}M$ ouabain. Above $10^{-6}M$ ouabain, a transient initial increase followed by a decrease in spike frequency and amplitude was produced, and finally membrane potential was sustained at a certain level without a spike discharge. 3) The characteristic response to $10^{-7}M$ ouabain was not blocked by the pretreatment with $10^{-7}M$ atropine. 4) The electrically induced contractions were completely suppressed at the concentration of $2{\times}10^{-7}M$ ouabain. These contractions were blocked more rapidly in paralled with the increase in ouabain concentration. 5) Effects of vanadate on the spontaneous activities were quite different from those of ouabain; $10^{-6}M$ vanadate increased the amplitude of contractions and $10^{-5}M$ vanadate increased slightly both amplitude and frequency of spontaneous contractions. $10^{-4}M$ vanadate showed irregular phasic contractions superimposed on the increased basal tone. 6) $10^{-5}M$ vanadate depolarized the membrane potential and shortened the interval between the bursts of spike discharge, whereas $10^{-4}M$ vanadate induced continuous spike discharge with membrane depolarization. 7) Vanadate caused a characteristic inhibitory response to the contractions induced by electrical stimulation; An initial rapid inhibition of tension development and then gradual recovery to a certain level. From the above results, the following conclusions could be made: 1) The rise of basal tone at $10^{-7}M$ ouabain is due to continuous spike discharge without a silent period. The continuous spike discharge is likely to be associated with a slight membrane depolarization caused by the blockage of Na pump. 2) The biphasic response induced by above $10^{-6}M$ ouabain seems to occur by the different mechanisms. The initial increase in tension is associated with depolarization along with an increase in spike frquency, whereas the subsequent relaxation occurs through a non-electrical mechanism. 3) The characteristic response to $10^{-7}M$ ouabain is resulted not from the action on intrinsic nerve terminal, but from its direct action on the membrane of smooth muscle cells. 4) The phasic contractions superimposed on the increased basal tone at the concentration of $10^{-4}M$ vanadate is resulted from the continuous spike discharge with membrane depolarization, of which mechanism remains unknown. 5) The inhibitory action of ouabain on the electrically induced contractions suggests that the increasein intracellular Na in some way inhibits the electrically induced $Ca^{2+}$ influx. The mechanism of vanadate action on the induced contractions remains unknown.

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