• The Korean Journal of Pharmacology
• /
• v.8 no.1
• /
• pp.31-40
• /
• 1972

The author studied the actions of ouabain and diphenylhydantoin sodium on the ATPase activity in mitochondrial fraction isolated from rabbit heart and compared with that of quinidine. The results obtained are as follows: 1) In studying the $(Na^++K^+)-activated$ ATPase activity, the rabbit heart isolated was immediately frozen for 7-9 days (ageing of preparation) and thereafter the mitochondria1 fraction obtained by differential centrifugation technic was treated with solution A containing 0.15% deoxycholate for 24-48 hours at $-10^{\circ}C$ before using in experiment. These methods increased the activity ratio to 0.87-0.98. 2) The $(Na^++K^+)-activated$ ATPase activity in mitochondrial fraction of rabbit heart was not completely but markedly inhibited by ouabain. This inhibitory action of ouabain was moderately antagonised by $K^+$ concentration at constant Na concentration. 3) Diphenylhydantoin sodium in concentration of $5{\times}10^{-4}{\sim}10^{-3}M$ stimulated markedly not only $Mg^{++}-dependent$ ATPase activity but also $(Na^++K^+)$-activated ATPase activity and in concentration lower than $10^{-6}M$ had little effect. However, this effect of diphenylhydantoin was markedly increased in the presence of $Na^+$ alone rather than $K^+$ alone, but lesser than that effect in the presence of both $Na^+$ and $K^+$, together. The stimulating effect of diphenylhydantoin was specifically antagonized by ouabaion. 4) When the rabbits were intravenously injected with ouabain and diphenylhydantion respectively, $(Na^++K^+)-activated$ ATPase activity of rabbit heart of ouabain-treated group was much decreased and both $(Na^++K^+)-activated$ ATPase and $Mg^{++}-activated$ ATPase activity were moderately increased in diphenylhydantoin-treated rabbit group. 5) The $(Na^++K^+)-activated$ ATPase activity in mitochondrial fraction of rabbit heart was slightly inhibited by quinidine in high concentration of $10^{-4}M$, but nearly little effect was observed below the concentration of $5{\times}10^{-5}M$. 6) It might be possible to conclude that diphenylhydantoin specifically antagonised the action of ouabain on the membrane ATPase, which is different from the action of quinidine.

• YAKHAK HOEJI
• /
• v.30 no.3
• /
• pp.149-156
• /
• 1986

Many experiments have showed that the sodium and potassium ion transporting system and the Na, $^+K^+$-ATPase activity of membrane fragments are inhibited by digitalis glycosides and that the pump may be associated with the pharmacological receptor for the drugs. The aim of our investigation is to elucidate the ouabain binding sites occupation in heart following infusion of ouabain to intact animals by the $^3H$-ouabain binding assay. Lethal dose and 26 percent of lethal dose of ouabain were infused to intact rabbit through ear vein. Microsomal fraction was fractionated from ouabain treated rabbit heart. $^3H$-ouabain binding to these fraction in vitro was studied by the Schwartz's method. $^3H$-ouabain binding to heart microsomal fraction was also studied following infusion of ginseng ethanol extract and caffeine to rabbits respectively. 1) The infusion of lethal dose ouabain (113$\mu\textrm{g}$/kg) inhibited the specific $^3H$-ouabain binding to rabbit heart microsomal fraction to the level of 60% (p<0.01) of control group and the infusion of 26% of lethal dose of ouabain led to the level of 79% (p<0.01) of the control group. 2) Time course of binding of 0.4$\mu{M}$ $^3H$-ouabain to microsomal fraction from rabbit heart following infusion of lethal and 26% of lethal dose of ouabain showed dose dependence at various incubation time. 3) Compared with control, only slight change of $K_d$ and $B_{max}$ was detected in in vitro $^3H$-ouabain binding after infusion of ginseng ethanol extract (300mg/kg) to rabbit. 4) In caffeine infusion group, $^3H$-ouabain binding yielded nearly the same results as control group.

• Journal of Chest Surgery
• /
• v.22 no.6
• /
• pp.887-893
• /
• 1989

Donor availability is a major limiting factor in heart transplantation. Prolonging donor heart preservation would facilitate distant heart procurement. The setup used was the isolated retrograde perfused nonworking rabbit heart model and 4 hours of preservation at 2oC. And the electron microscopic findings of the myocardium were evaluated after reperfusion for 5 minutes. The following three groups [each group, n=4] were prepared: Group I: the heart was arrested with the St. Thomas Hospital solution [STH] and stored in Ringers lactate solution [RLS]; Group II: the heart was arrested with STH and stored in Modified Collins-Sachs solution [MCS]; Group g: the heart was arrested with and stored in MCS. The result was the most severe myocardial injury in the Group III on electron microscopic study.

• The Korean Journal of Physiology and Pharmacology
• /
• v.4 no.5
• /
• pp.417-425
• /
• 2000

The underlying mechanism commonly applicable for both the positive and negative force-frequency relationships (FFR) was pursued in left atria (LA) of rat and rabbit. The species differences in the roles of $Na^+/Ca^{2+}$ exchanger and sarcoplasmic reticulum (SR), which are major intracellular $Ca^{2+}$ regulatory mechanisms in the heart, were examined in the amplitude accommodation to the frequency that changed from 3 Hz to the variable test frequencies for 5 minutes in the electrically field stimulated left atria (LA) of rat and rabbit. Norepinephrine strongly increased the frequency-related amplitude accommodation in both of rat and rabbit LA, while monensin, oubain or the reduced $Na^+$ and 0 mM $Ca^{2+}$ containing Tyrode solution increased the frequency-related amplitude accommodation only in the rabbit LA. Monenisn was also able to increase the frequency-related amplitude accommodation only in 1-day old rat LA but not in 4-week old rat LA that had 75% less $Na^+/Ca^{2+}$ exchanger with 97% higher SR than 1-day old rat LA. Taken together, it is concluded that the differences in the prevalence between myocardial $Na^+/Ca^{2+}$ exchanger and SR in the amplitude accommodation to the frequency-change determine the difference in the FFR between rat and rabbit heart.

• The Journal of Korean Medicine
• /
• v.17 no.2 s.32
• /
• pp.264-276
• /
• 1996

This study was carried out to evaluate the effect of Samhwasan on the Na-K-ATPase activity of heart muscle. The Na-K-ATPase activity was prepared from rabbit heart ventricles. Samhwasan markedly inhibited the Na- K - ATPase activity in a dose-dependent manner with an estimated $I_{50}$ of 0.56%. Hill coefficient was 1.70, indicating that the enzyme has more than one binding site for the Samhwasan. Inhibition of enzyme activity by Samhwasan increased as pretreatment time was prolonged. Inhibition by the drug was not affected by a change in enzyme protein concentration. Kinetic studies of substrate activation of the enzyme indicated classical noncompetitive inhibition, showing significant reduction in Vmax without a change in Km value. Inhibitory effect by Samhwasan was not altered by changes in concentration of $Mg^{2+}$, $Na^+$ or $K^+$, dithiothreitol. a sulfhydryl reducing reagent, did not protect the inhibition of Na-K-ATPase activity by Samhwasan combination of Samhwasan and ouabain showed a cumulative inhibition fashion. These results suggest that Samhwasan inhibits Na-K-ATPase activity of heart ventricles with an unique binding site different from that of ATP, $Mg^{2+}$, $Na^+$ or $K^+$ and ouabain.

• The Korean Journal of Physiology
• /
• v.26 no.1
• /
• pp.27-35
• /
• 1992

We used the whole cell patch clamp technique to examine the ionic basis for the tail current after depolarizing pulse in single atrial myocytes of the rabbit. We recorded the tail currents during various repolarizations after short depolarizing pulse from a holding potential of -70 mV. The potassium currents were blocked by external 4-aminopyridine and replacement of internal potassium with cesium. The current was reversed to the outward direction above +10 mV. High concentrations of intracellular calcium buffer inhibited the activation of the current. Diltiazem and ryanodine blocked it too. These data suggest that the current is activated by intracellular calcium released from sarcoplasmic reticulumn. When the internal chloride concentration was increased, the inward tail current was increased. The current was partially blocked by the anion transport blocker niflumic acid. The current voltage curve of the niflumic acid sensitive current component shows outward rectification and is well fitted to the current voltage curve of the theoretically predicted chloride current calculated from the constant field equation. The currents recorded in rabbit atrial myocytes, with the method showing isolated outward Na Ca exchange current in ventricular cells of the guinea pig, suggested that chloride conductance could be activated with the activation of Na/ca exchange current. From the above results it is concluded that a chloride sensitive component which is activated by intracellular calcium contributes to tail currents in rabbit atrial cells.

• The Korean Journal of Pharmacology
• /
• v.14 no.1_2
• /
• pp.41-46
• /
• 1978

The effects of sodium taurocholate(STC) and sodium deoxycholate(SDC) on cardiac function were examined by using isolated atria of rabbit and guinea pig and heart of anesthetized frog. Also the antiarrythmic action of STC and SDC on atrial arrhythmias induced by epinephrine or ouabain was studied. The results were following. The cholates exhibited a slight decrease in rate and contractile amplitude of the isolated rabbit atria. The cholates abolished partially the spontaneous arrhythmic occurring in isolated rabbit and guinea pig atria but no effect on the atrial arrhythmia induced by ouabain and epinephrine was observed. Concomitant administration of cholates with ouabain produced a marked prolongation of atrial arrhythmia in comparison to that of ouabain alone in both isolated rabbit and guinea pig atria. The cholates exhibited a marked prolongation in ventricular arrhythmia and cardiac arrest time in comparison to that of ouabain treatment. However, the combined treatment with cholates and ouabain produced a slight prolongation in comparison to that of ouabain alone in the heart of anesthetized frog. The above results suggest that cholates have a slight antiarrythmic effect on the heart but this effectiveness is different from those of propranolol that is non-selective antiarrhythmic drug.

• The Korean Journal of Physiology
• /
• v.9 no.1
• /
• pp.13-22
• /
• 1975

From the study of movements of $Ca^{++}$ in frog cardiac muscle, Niedergerke (1963) postulated that $Ca^{++}$ necessary for the cardiac contraction is stored in a specific pool. Langer et al (1967) and DeCaro (1967) also found a close relationship between the change of $Ca^{++}$ flux kinetics and the change of contractile force. According to the studies of several investigators, Ca II (Bailey and Dressel 1968) or phase I and II (Langer 1965, Langer et al 1967, 1971) in the $Ca^{++}$ washout curve was associated with cardiac contractility. This investigation was aimed to elucidate the anatomical region of the contractile active $Ca^{++}$ pool. At the same time, it was assumed in this study that $Ca^{++}$ in the sarcoplasmic reticulumn represents one of the major intracellular $Ca^{++}$ pool and cardiac contractility was also dependent on the intracellular $Ca^{++}$ concentration. Consequently, this experiment was performed at different temperatures to activate to activate inhibit the deactivating process of activated $Ca^{++}$ in the intracellular space to see if changes in the contractility decay curve existed at different temperatures. The isolated hearts of rabbits and turtles (Amyda maackii) were attached to the perfusion apparatus according to the method employed by Bailey and Dressel (1968). The isolated hearts were initally perfused with a full Ringer solution containing 2 mg/ml of inulin for 1 hr, and then $Ca^{++}$ and inulin-free Ringer solution was perfused while the isometric tension was recorded and a serial sample of perfusion fluid dripping from the cardiac apex was collected for 10 sec throughout experimental period. The above procedure was performed at $23^{\circ}C$, $30^{\circ}C$ and $38^{\circ}C$ on the rabbit heart and $10{\sim}13^{\circ}C$, $10^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$ and $35^{\circ}C$ on the turtle heart. After determination of $Ca^{++}$ and inulin concentration of the samples, the $Ca^{++}$, inulin washout curve and the contractile tensin decay curve were analysed according to the method of Riggs (1963). The results were summarized as follows; 1. In the rabbit heart, there are 2 inulin compartments, 3 $Ca^{++}$ compartments and sing1e exponential decay of contractile tension. In the turtle heart, there are $1{\sim}2$ inulin compartments, $1{\sim}2$ $Ca^{++}$ compartments and $1{\sim}2$ phases of contractile tension decay. The fact that the inulin space was divided into 3 compartments in the washout curve in these hearts indicates the presence of heterogeneity in cardiac perfusion, i.e., overfused and underperfused area. 2. Ca I a9d Ca II in these hearts were found to have $Ca^{++}$ in the ECF compartments because their half times in the washout curves were far smaller than those of the inulin washout curves in the rabbit heart and similar to those of the inulin washout curves in the turtle heart. Ca III in the rabbit heart may have originated from the intracellular $Ca^{++}$ store. But no Ca III in the turtle heart was found. This may be due to the fact that the iutracellular $Ca^{++}$ pool in the turtle heart was too small to detect using this experimental procedure since sarcoplasmic reticulumn in the turtle heart is poorly developed. 3. In the rabbit heart, there were no chages in the half time of Ca I, Ca II, inulin I and inulin II at different temperatures, but the half time of Ca III was significantly prolonged at lower temperatures, and the half time of the contractile tension decay tended to be prolonged at lower temperatures but this was not significant. In the turtle heart, there were no changes in the half time of Ca I, Ca II, inulin 1, inulin II and phase I of the contractile tension decay at different temperatures, but the half time of phase II of the contractile tension decay was significantly prolonged at lower temperatures. This finding indicates that intracellu!ar $Ca^{++}$ in these hearts was also responsible particulary for maintaining the cardiac contractility at the lower temperatures. 4. The half times of contractile tension decay were shorter than those of Ca II in the $Ca^{++}$ washout curves in both animal hearts. According to the above results it was shown that $Ca^{++}$ in ECF is primarily and $Ca^{++}$ in the intracellular space is partially associated with the cardic contractility.

• The Korean Journal of Pharmacology
• /
• v.12 no.1
• /
• pp.7-14
• /
• 1976

Aconiti tuber butanol fraction shows positive inotropic effect on the isolated atrium of rabbit heart. To investigate the mechanism, the effect on microsomal ATPase activity of rabbit heart is observed. The microsomal fraction which contains the $Na^+$- and $K^+$-activated ATPase in the presence of $Mg^{++}$ is isolated from the left ventricle of rabbit heart. The microsomal ATPase activity is maximally stimulated at $Na^+$ and $K^+$ concentration of 100 mM and 10 mM respectively. Microsomal $Na^+-K^+$-activated ATPase is inhibited by ouabain and Aconiti tuber butanol fraction. Ouabain and Aconiti tuber butanol fraction depress $Na^+$-stimulation on microsomal ATPase activity, and the inhibitory effects are not completely reversed at $Na^+$ concentration of 300 mM. Also, $K^+$-stimulation on microsomal ATPase activity is inhibited by ouabin and Aconiti tuber butanol fraction and the inhibitions are not compeletely reversed at $K^+$ concentration of 30 mM. It is, therefore, suggested that the inhibitory effect of Aconiti tuber butanol fraction on the microsomal ATPase activity may contribute to leading to the positive inotropic effect.

• Journal of Pharmaceutical Investigation
• /
• v.12 no.3
• /
• pp.93-99
• /
• 1982

The effects of erythrosine on motility of frog heart, rabbit duodenum and uterus isolated, and on mice intestinal motility and voluntary activity were investigated. The effect of erythrosine $2.3{\times}10^{-5}M$ on isolated frog heart showed a slight decrease of the amplitude of motility, and the heart motility stopped in $3.5{\times}10^{-4}M$. With the administration of erythrosine $3.4{\times}10^{-4}M$, the isolated rabbit duodenum showed a remarkable contraction and this effect was inhibited by atropine $1.4{\times}10^{-7}M$. The administration of erythrosine $2.3{\times}10^{-3}M$, produced a contractile effect on the isolated rabbit uterus, and the motility of $6.9{\times}10^{-3}M$ started to increase in contractions at first and finally stopped, keeping in continuous contractions. The effects of erythrosine 0.5, 1.0, 10, and 20mg/kg on mice intestinal motility were not significantly different from this of the normal control. With 20 and 40mg/kg of erythrosine, the effects on voluntary activity showed the decrease of 21 and 58% respectively, and voluntary activity of the mice pretreated with erythrosine 20 and 40mg/kg, induced by C. N. B. 30mg/kg showed the decrease of 57 and 78% respectively in contrast with the normal control group.