위 평활근 세포의 활동전압을 이루는 CI^-전류성분에 관한 연구

방효원,이종찬,이무열,엄대용,이상돈 중앙대학교 의과대학 의과학연구소 1993 中央醫大誌 Vol.18 No.3

Chloride current has been known as a part of backgroud current. Recently, its roles in the maintenance of action potential have much attention. The purposes of the present study are clarifying the chloride current component which might play an important role in generation and maintenance of the action potential in the pyloric circular smooth musele cells. We used the whold cell voltage clamp techniques to assess the current and voltage responses induced by caffeine superfusion. The results were as follow: 1. Caffeine superfusion induced the increase of inward currents in the hyperpolarized potential ranges, and the increase of outward currents in the depolarized ranges. 2. Sodium ion removal from the external medium and the addition of cadmium ion rarely affected these current response. 3. Duration of the action potential was elongated by application of the caffeine and modified by the change of the intracellular chloride ion concentraion. 4. The effect of caffeine superfusion on the action potential disappeared by the addition of the anion channel blocker. The results suggest that caffeine superfusion may prolong the duration of repolarized phase of the action potential probably by the chloride current activation in the gastric antral smooth muscle.

한국산 뱀독이 개구리 심장심실 근육 세포의 활동전압에 미치는 영향

정해성,방효원,엄대용,이상돈 중앙대학교 의과대학 의과학연구소 1984 中央醫大誌 Vol.9 No.2

Action potential of a frog ventricular cell was studied by conventional 3M KCI glass microelectrodes to investigate the effect of freeze-dried Korean snake venom. Following results were obtained; 1. Time to repolarize 50% of its action potential increased from 756±26mS to 796±17mS. 2. The notch which would be seen after the fast depolarization disappeared and the overshoot potential significantly decreased from 24.4±0.9㎷ to 17.8±2.3㎷. 3. Positive depolarization rate (dV/dt max) decreased from 22.8±0.8V/s to 18.8±0.8V/s. 4. Resting membrane potential was -95±3.0㎷ and showed little change. Above results would be interpreted that the Korean snake venom blocked the fast sodium channel and slow calcium channel simultaneously to reduce the contractility and activation of potassium channel which could result the prolongation of action potential duration.

위 유문동 평활근세포의 Caffeine 활성화 전류에 미치는 Ascorbate의 효과

이무열,방효원,엄대용,이상돈 중앙대학교 의과대학 의과학연구소 1992 中央醫大誌 Vol.17 No.4

In order to observe the effects of ascorbate on the background current in pyloric circular smooth muscle cells, caffeine of which action was fairly clarified, was used to induce the current systems. To block all of the known currents, various blocking agents were added in the external bathing solution. A part of pyloric circular muscle tissue was excised out, and enzymatic isolation technique was used to obtain Ca^2+ -tolerant single circular muscle cells. The whole cell mode of patch-clamp experiment was conducted. The results were as follows : 1. Ascorbate induced the increase of inward currents in the hyperpolarized potential ranges, and quite a large increase of outward currents in the depolarized ranges. 2. Caffeine also induced similar results, but the magnitude of outward current was smaller than that of assorbate in the depolarized ranges. 3. These phenomena were disappeared by addition of the anion channel blocker. 4. Replacement of external NaCl with NMG·Cl was rarely affected the effects of ascorbate and and caffeine. But the effects of ascorbate and caffeine were almost abolished when sxternal Cl^- was substituted for aspartate. These results suggested that ascorbate affected chloride current which thought as a component of the background currents in the pyloric circular smooth muscle cells.

한국산 뱀독이 개구리 심실근육세포의 수축력과 활동전압에 미치는 영향

한형일,방효원,엄대용,이상돈 중앙대학교 의과대학 의과학연구소 1984 中央醫大誌 Vol.9 No.3

In order to observe the effects of freeze-dried saliva of Agkistrodon caliginosus and Agkistrodon saxatilis, the Korean poisonous snakes, on the contractility and action potential of frog ventricular muscle cells, the isometric tension in a vertical chamber and the action potential in horizontal chamber were recorded and analyzed. The following results were obtained; 1. ED_50, to reduce the contractility was 4-8ug/ml in the case of A. saxatilis and 8-16ug/ml in the case of A. caliginosus which all were higher than that of A. brevicaudus and the inhibitory effect on the contractility was greater in the case of A. saxatilis than that of A. caliginosus. 2. In the case of A. saxatilis, APD_50(time to repolarize 50% of action potential amplitude) decreased from 820±80 ms to 710±60 ms, the overshoot and the V max(Maximum depolarization rate) decreased from 34±8 mV to 18±4 mV, from 98±8 V/s to 89±4 V/s respectively. 3. In the case of A. caliginosus, ADP_50 decreased from 880±70 ms to 720±40 ms, the overshoot and the V max decreased from 28±6 mV to 20±4 mV, from 89±8V/s to 77±12V/s, respectively. 4. Inhibition of contractility and overshoot potential were more prominent in A. saxatilis and APD_50 was more decreased in A. caliginosus. The above result showed that Korean snake venoms would decrease the ionic current underlying the rapid upstroke phase and slow inward currents by calcium ions simultaneously in a frog ventricular muscle cells.

집토끼 동방결절의 활동전압에 미치는 Vanadate의 효과

조용문,방효원,엄대용,이상돈 중앙대학교 의과대학 의과학연구소 1984 中央醫大誌 Vol.9 No.3

In order to investigate the electrphysiological effect of vanadate, a potent inhibitor of Na^+-K^+ pump, on the cardiac muscle, the alteration of transmembrane potential as influenced by the drug was measured in rabbit SA rodes in vitro by means of KCI glass intracellular microelectrodes. The followings were results of findings: 1. The rate of spontaneous firing was decreased in the presence of vanadate and the maximum inhibition which was about 50% of contral level was obtained at drug concentrations of 10^-3 M or higher. 2. The maximum diastolic potential(M.D.P.) was depressed by vanadate in a dose-dependent manner and the maximum inhibitory effect was obtained at the drug concentration of 10^-3 M. However the peripheral pacemaker cells were more resistant to the drug effect than the central pacemaker cells at lower concentrations of the drug. 3. In both central and perepheral pacemaker cells, vanadate had no effect on the M.D.P. in concentrations up to 5×10^-4 M. However on at 5×10^-2 M, the drug depressed the M.D.P. in the peripheral cells. 4. Changes of the action potential induced by vanadate were qualitatively similar to those occuring when the calcium concentration of the bathing medium was raised to 4mM. These results may be interpreted as that vanadate increases the rate of Ca^++ influx info the cell in S-A nodes.

한국산 뱀독이 개구리 심방근 수축에 미치는 효과

한종희,방효원,엄대용,이상돈 중앙대학교 의과대학 의과학연구소 1984 中央醫大誌 Vol.9 No.1

In order to observe the effect of freeze-dried saliva of Korean venomous snake, Agkistrodon blomhoffii brevicaudus, on the contractility of spontaneously beating frog atrial muscle, a muscle strip was prepared and immersed in a vertical force recording chamber in frog Ringer solution containing 10^-7M propranolol. Isometric contraction was recorded and the following results wers obtained. 1. Developed tension of an atrial muscle strip increased with the increase of external calcium ion concentration, from 0.66mM up to 3.3mM but little change was observed in spontaneously beating frequency. 2. Inverse relationship was observed between the contractility and its driving frequency in venomtreated group. 3. The contractility decreased slightly in high(16∼32㎍/m㎖) venom concentration group but the beating frequency showed no definite correlation with the venom concentration. The above results suggested that Korean snake venom inhibited the influx of calcium ion across cell membrane to reduce the contractility like that in a ventricular muscle cell although the degree was slight.

Papaverine이 단일 심근세포의 막전류에 미치는 영향

유경현,심태섭,방효원 중앙대학교 의과대학 의과학연구소 1991 中央醫大誌 Vol.16 No.4

Ventricular myocytes of guinea-pig were isolated by means of collagenase digestion in order to investigate the effects of papaverine on the membrane currents in them. After formation of a gigaseal with patch microelectrodes, membrane currents were recorded from single ventricular myocytes in a whole cell mode of patch-clamp technique. For membrane currents recording, electrodes were filled with Cs-solution. Results were as follows: 1. Slow inward calcium was reduced by papaverine dose-dependently. 2. No significant changes were observed in the steady-state inactivation. 3. Recovery time of the calcium currents prolonged in high concencial papaverine. 4. Fast inward sodium currents showed no noticeable changes with papaverine treatment. From these results, it is strongly suggested that the effects of papaverine on the membrane currents in the single ventricular myocytes may be attributable to its antagonistic action on the calcium channel rather than its inhibitory effect on the phosphodiesterase activity.

위 유문동 평활근 세포에서 Caffeine에 의해 활성화되는 이온 전류에 관한 연구

정인원,이무열,방효원,엄대용,이상돈 중앙대학교 의과대학 의과학연구소 1992 中央醫大誌 Vol.17 No.3

In order to clarify the existence of the non-selective cationic channel of CI^- -channel in gastric antral smooth muscle cells which suggested to play a critical role in generation and maintenance of depolarization and exitability, the whole cell mode of patch-clamp experiment was conducted. Following results were obtained ; 1. Puff injection of caffeine induced the increase of inward currents in the hyperpolarized holding potential ranges, and the increase of outward currents in the hypopolarized range. 2. In the case of blocking of all known currents, these current components were observed. 3. These current components were disappeared when known as a Cl^- -channel blocking agent was treated and intracellular EGTA concentration was increased. The above results could be concluded that these current components strongly suggested as a Ca^2+ -dependent Cl^- current in the gastric antral smooth muscle cells.

위 윤상근 세포의 Ca^2+-의존성 K^+-전류에 미치는 Ascorbate의 효과

배정원,이무열,방효원,엄대용,이상돈 중앙대학교 의과대학 의과학연구소 1991 中央醫大誌 Vol.16 No.2

In order to observe the effect of ascorbate on the Ca^2+-activated K^+ current in pyloric circular muscle cells which plays a critical role in generation and maintenance of repolarization and automatism, apart of pyloric circular muscle tissue was excised out, digested in collagenase containing Ca^2+-free physiological solution to get single circular muscle cells and the whole cell mode of patch-clamp experiment was conducted. Following results were obtained : 1. Oscillatory outward current was reduced by ascorbate in case of high intrapipette Ca^2+ concentration in whole voltage range and was enhanced in case of low intrapipette Ca^2+ concentration. 2. Oscillatory outward current was reduced in Ca^2+-free physiological solution with calcium channel blocker and not effected by ascorbate. 3. There were no qualitative differences among the control and ascorbate-treated group in effects of pH, steady state inactivation and the remaining component of the outward current. The above results could be concluded that ascorbate effects calcium-dependent component of the oscillatory outward current in the pyloric circular smooth muscle cells.

Guinea pig 단일 심실근 세포의 칼슘전류에 대한 아드레날린성 약물의 효과

백승곤,심태섭,방효원 중앙대학교 의과대학 의과학연구소 1991 中央醫大誌 Vol.16 No.4

In order to investigate the effects of sympathomimetic drugs on the calcium currents, whole cell patch clamp technique was used in ventricular cells of the guinea-pig. Single ventricular cells were isolated by Langedorff perfusion method with collagenase. T-type and L-type Ca-currents were recorded in different holding potentials. T-type Ca-current was activated from more negative membrane potentials(around -50 mV) and was inactivated very rapidly, whereas L-type Ca-current was activated from -30 mV and inactivated with two time constants(fast and slow components). Replacement of calcium with barium increased the activation magnitude of L-type Ca-current and delayed inactivation time course, but did not affect T-type Ca-current significantly. Nifedipine blocked and Bay K 8644 increased L-type Ca-current with voltage-dependent manner. T-type Ca-current, however, was relatively insentive to dihydropyridine compuonds. Isoproterenol which is known to have mainly beta-agonist increased L-and T-type Ca-currents and propranolol reversed the effect of isoproterenol. Phenylephrine(alpha-agonist) and phentolamine(alpha-blocker) have no significant effects on the Ca-currents. From the above results it is suggested that L-type and T-type Ca-currents are present in guineapig ventricular myocytes and very sensitive to beta-agonist or-antagonist, but relatively insensitive to drugs acting on alpha-receptors.