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개구리 대동맥의 활동전압 및 Pacemaker 전압에 관한 연구
엄융의,성호경,Earm, Yung-E,Sung, Ho-Kyung 대한생리학회 1982 대한생리학회지 Vol.16 No.2
The frog truncus arterious were studied with conventional glass microelectrode technique in order to elucidate the underlying mechanism of spontaneous pacemaker activity. The analyses were focussed on the ionic nature of pacemaker current by changing the concentrations of extracellular $K^+$ and, $Na^+$, or by using blockers of K- and Ca-current and chronotropic transmitters. 1) The action potential of the spontaneously active truncus arteriosus has some characteristic feature of maximal distolic potential ranged from -65 to -75 mV, resting potential from -45 to -50 mV and overshoot voltage about +30 mV, respectively. Duration of the action potential taken from rapid upstroke to maximal diastolic potential was about 600 msec. Usual discharge rate was $25{\sim}30/min$ at room temperature $(18{\sim}20^{\circ}C)$. 2) The sensitivity of the resting membrane potential to change extracellular potassium concentrations $(0{\sim}12\;mM)$ was relatively low. Transient hyperpolarization was appeared in the 12 mM K Ringer after 10 min exposure to 0 mM K and it could be related to Na-pump reactivation by high potassium. 3) Reduction of extracellular sodium concetrations diminished the amplitude and frequency of the action potential. In Ringer solution containing 30% Na (substituted by equimolar Tris), spontaneous activity stopped but reappeared as very slow and small action potential. There was no spotaneous activity in zero Na Ringer solution. 4) Caesium(10 mM), K-current blocker decreased the frequency of the action potential and also pacemaker depolarization. Manganese (2 mM) known to be Ca-current antagonist, blocked spontaneous activity completely. 5) Adrenaline and acetylcholine had no chronotropic effect. But adrenaline increased the duration of plateau phase and the magnitude of the action potential in the follower cell. It is concluded that K-, Na-and Ca-current components are involved in the genesis of spontaneous activity of the frog truncus arteriosus like cardiac pacemaker tissues. But the insensitivity of truncus arteriosus to adrenaline and acetylcholine indicates that there are some different control mechanisms of spontaneous rhythm in two tissues.
생물정보학과 환원주의 - 생물정보학은 Computational Molecular Biology와 동의어인가?
엄융의,Eom, Yung-Eui 한국생물정보시스템생물학회 2006 Bioinformatics and Biosystems Vol.1 No.1
현대 생물학은 온통 정보의 홍수에 넘쳐나고 있다. 이렇게 쏟아져 나오는 정보들을 체계적으로 정리하고 이해하고 파악하는 것은 매우 중요하다고 하겠다. 생물정보학은 이렇게 쏟아져 나오는 정보들을 수학, 전산학, 정보학 등의 방법론을 사용하여 체계화시키려는 새로운 학문이고 미래 지향적 융합 분야이다.
토끼 동방결절 세포의 Delayed Rectifier K+ 전류에 미치는 이가 양이온의 차단효과
송대규,호원경,엄융의 啓明大學校 醫科大學 1996 계명의대학술지 Vol.15 No.3
In sinoatrial(SA) node cells, K+ conductance increases only when the membrane is depolarized and the delayed rectifier K+ current, ik, is activated. This leads to repolarizaion which in turn induces the deactivation of channel, causing the membrane potential to depolarize once again towards the threshold of the action potential. Therefore the decay of ik plays a key role in the pacemaker depolarizaion. In the present study, we have investigated the effects of divalent cations(Ni²+, Ba²+, Co²+, and Mn²+) on the delayed rectifier K current in rabbit SA node cells using the whole cell votage clamp technique. CsCl(2 mM) was added to block the hyperpolarizaion activated inward current(ir). K+ currents were recorded in ligh K+ (140 mM) solution. When divalent cations were added to a control solution, they reduced both the instantaneous and the steady-state values of currents recorded on hyperpolarizaion. The blockade was potential-dependent, and steady-state currents were significantly reduced with increasing hyperpolarizaion. The inward currents that recorded during hyperpolarizing voltage steps were relaxed exponetially with time as the blockade by divalent cations developed. Increased the concentraion of the divalent cations elevated the rate of the blockade at a given potential. These phenomena were highly sensitive to temperature, suggesting the presence of ionic binding sites on the channel. Inward K+ currents measured at-80 mV after various depolarizing prepulses(-10 to -40mV) were increased in the more depolarizing prepulses, and showed the steady-state blocking evidence at 0.1 mM Ni²+. Ni²+, Ba²+, Co²+, and Mn²+ had a similar effect, but the velocity of the blocking action is slightly different from one another(Ni²+>Co²+>Mn²+>Ba²+).