Characteristics of the action of the cardiac nerve Tomio Kanno 1 , Takehike Azuma 1 , Kojiro Matsuda 1 1Department of 1st Physiology, Tokyo University School of Medicine pp.233-240
Published Date 1963/10/15
DOI https://doi.org/10.11477/mf.2425906291
  • Abstract
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 Nervous control of cardiac activity was investigated precisely on the perfused sino-atrial preparation of toad. Results obtained were summerized as follows:

 1) Effects of cardiac nerve stimulation could be classified into six:

 (1) electroklinotropic (changes in the shape of action potential, especially in its rate of repolarization), (2) mechanoklinotropic, (3) chronotropic, (4) inotropic, (5) bathmotropic and (6) dromotropic. Usually, the electroklinotropic effect was produced by the weakest stimulation. As the strength of the stimulation was increased progressively, remaining five effects were produced in the order described above.

 2) All the effects except the dromotropic could be brought about by a single supramaximal vagal shoch of 0.01 msec in duration and they disappeared within a few seconds. A single supramaximal sympathetic shoch could produced the electroklinotropic, mechanoklinotropic, chronotropic and inotropic effects only when its duration was more than 0.1 msec. These effects continued for several minutes after stimulation.

 3) The negative chronotropic effect brought about by a single vagal shock varied to the time at which the nerve is stimulated. It became maximum by applying the stimulation 1.7 sec prior to the succeeding sinus excitation.

 4) No differences could be observed between the actions of the right and left cardiac nerve of toad.

 5) Effects of vagal and sympathetic stimulation were dependent upon the frequency of stimulating current. Both of them became maximum at the frequency of 20/sec.

 6) Reversal of bathmotropic effect was observed in the course of long lasting vagal and sympathetic stimulation.

 7) Direct strong stimulation of the atral muscle produced vagus-like effects, i.e. negative electro-klinotropic, mechanoklinotropic, inotropic, chronotropic and bathmotropic effect.

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