The Effect of Drugs on the Cardiac Membrane Potentials in the Rabbit

Matsumura, Michikazu; Takaori, Shuji

doi:10.1254/jjp.8.143

Cited by 19 publications

(5 citation statements)

References 20 publications

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“…As an indifferent electrode a platinum wire immersed in the nutrient solution of the bath was used. The potential changes of the single muscle fiber were recorded follow ing the method of Matsumura and Takaori (7). The potential changes amplified through d.c. amplifier were photographed from a cathode-ray oscilloscope by use of a continuous recording camera.…”

Section: Methodsmentioning

confidence: 99%

Effects of Reserpine and Adrenaline on the Sinoatrial Notched Potential in Rabbit

Toda

1962

Japanese Journal of Pharmacology

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In the course of studies in this laboratory on the mode of action of catecholamines on the transmembrane potential of the extirpated atrium of rabbit (1), some of the poten tials recorded from the pacemaker area (West) responded differently to reserpine and adrenaline from the typical pacemaker potentials. The potential under this study was recorded from the area which was somewhat wider than the triangular pacemaker area shown schematically by West (2). This potential was characteristic in a notching of the upstroke and a slow rate of depolarization, and was very sensitive to reserpine and adre naline. The notched potential in the sinoatrial node of rabbit's heart was at first reported by West (2), who studied the distribution of the potential. Although the similar notched potentials have been reported in the atrioventricular node of mammalian heart (3, 4), the smooth muscle of uterus (5) and the sinoauricular funnel of amphibian heart (6), the exact nature of the potentials remains to be settled. In the present report the responses of the notched potential recorded from the sinoatrial node of rabbit's heart were studied. It is expected that the responses of the potential to reserpine and adrenaline might have some contribution to elucidate the mechanism of the pacemaker activity. METHODSAlbino rabbits, weighing 1.8 to 2.2 kg, were killed through haemorrhage by cutting of both common carotid arteries. The heart was extirpated and the right auricle was separated from the heart. Immediately thereafter, the auricle was fixed on the cork plate immersed in warm (30°C) and 02 saturated modified Tyrode solution. The volume of the solution in the bath was 50 ml. The composition of the modified Tyrode solution is as follows : NaCI 8.6 g, KCl 0.2 g, CaCl, 0.2 g, MgCl2 0.05 g, NaH,P04 0.2 g, Na2HPO4 1.6 g and glucose 1.0 g in 1000 ml. The preparation always showed a rhythmical auto matic contraction for 8 to 14 hours.A glass capillary tube filled with 3 molar KCl solution was used as a different elect rode. As an indifferent electrode a platinum wire immersed in the nutrient solution of the bath was used. The potential changes of the single muscle fiber were recorded follow ing the method of Matsumura and Takaori (7). The potential changes amplified through d.c. amplifier were photographed from a cathode-ray oscilloscope by use of a continuous recording camera. When it was required, the potentials were recorded by use of an ink writing oscillograph.

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Section: Methodsmentioning

confidence: 99%

Effects of Reserpine and Adrenaline on the Sinoatrial Notched Potential in Rabbit

Toda

1962

Japanese Journal of Pharmacology

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“…The transitions in duration which occur in areas of infarction have been considered likely sites for this "boundary current" types of reexcitation (Kupersmith et al, 1976;Kleber et al, 1978). Experimental support for this theory has been proposed to come from the work of Matsumura and Takaori (1959). These authors found that, at reduced calcium concentrations, preparations of the right atrium containing the sino-atrial node showed very long action potential durations in the nodal regions and repetitive firing of atrial fibers after each nodal action potential.…”

Section: Regional Changes In Action Potential Durationmentioning

confidence: 99%

Simulated propagation of cardiac action potentials

Sharp¹,

Joyner²

1980

Biophysical Journal

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We have used numerical methods for solving cable equations, combined with previously published mathematical models for the membrane properties of ventricular and Purkinje cells, to simulate the propagation of cardiac action potentials along a unidimensional strand. Two types of inhomogeneities have been simulated and the results compared with experimentally observed disturbances in cardiac action potential propagation. Changes in the membrane model for regions of the strand were introduced to simulate regions of decreased excitability. Regional changes in the intercellular coupling were also studied. The results illustrate and help to explain the disturbances in propagation which have been reported to occur at regions of decreased excitability, regions with changing action potential duration, or regions with changing intercellular coupling. The propagational disturbances seen at all of these regions are discussed in terms of the changing electrical load imposed upon the propagating impulse.

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“…As described previously (1)(2)(3), the experiments were carried out on the right incised atrium of rabbits. The endocardial surface of the dissected right incised atrium was pinned on a cork block mounted in a lucite chamber containing about 10 ml of oxygen saturated Tyrode solution at approximately 30°C.…”

Section: Methodsmentioning

confidence: 99%

Effect of Anticholinesterases on the Membrane Potential of the Rabbit Heart

Takaori

Inoki

Toda

et al. 1961

Japanese Journal of Pharmacology

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We have already reported on the action of drugs such as acetylcholine, epinephrine, reserpine, cardiac glycosides, antiarrhythmic agents, veratrine and chelating agents on the intracellular action potentials recorded from the ventricular muscle, sinoatrial node and the non-pacemaker atrial fibers of the isolated rabbit heart using the ultramicro electrode method (1-3).The present experiments were undertaken to determine the influences of anticholin esterases on the membrane potentials of the isolated rabbit atrial muscle exhibiting spon taneous beating. Observations on the antagonisms between the action of anticholinesterases and of cholinesterase reactivators on the membrane potentials were also designed . METHODSAs described previously (1-3), the experiments were carried out on the right incised atrium of rabbits. The endocardial surface of the dissected right incised atrium was pinned on a cork block mounted in a lucite chamber containing about 10 ml of oxygen saturated Tyrode solution at approximately 30°C. The drugs were added directly to Tyrode solution in the chamber and their concentrations were expressed in terms of w/v (g/ml). Recordings of the transmembrane potentials from non-pacemaker and pacemaker areas were taken by the intracellular microelectrode. The recording electrode , less than 1 µ in diameter, drawn from special glass capillary tubing and filled with 3 M-KCI , having low resistance (8-20 MQ), was selected and fixed on the arm of a micromanipulator . A chloride silver wire was pushed into the shaft of the electrode and was soldered onto flexible strand thereby connected to a d.c. amplifier with an input cathode follower of low grid current and reduced grid-earth capacity. The output of the amplifier was led to a cathode-ray oscilloscope and ink-writing recorder (Sanei's Type MPA-204) .

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The Effect of Drugs on the Cardiac Membrane Potentials in the Rabbit

Cited by 19 publications

References 20 publications

Effects of Reserpine and Adrenaline on the Sinoatrial Notched Potential in Rabbit

Effects of Reserpine and Adrenaline on the Sinoatrial Notched Potential in Rabbit

Simulated propagation of cardiac action potentials

Effect of Anticholinesterases on the Membrane Potential of the Rabbit Heart

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