On the explanation of Stannius's experiment and on the action of strychnia on the heart / by T. Lauder Brunton and Theodore Cash.

  • Brunton, Thomas Lauder, Sir, 1844-1916.
Date:
[1880?]
Catalogue details

Licence: Public Domain Mark

Credit: On the explanation of Stannius's experiment and on the action of strychnia on the heart / by T. Lauder Brunton and Theodore Cash. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    4/10 (page 230)
    it would therefore appear that the still-stand of the heart in this experiment cannot be due to excitement of the inhibitory appa- ratus. The second explanation is, that the motor ganglia of the heart are unequally distributed in the ventricle and auricle, the greater number being in the venous sinus and ventricle, and the fewest in the auricle. When the sinus, then, is separated from the remainder of the heart, the motor power in the auricles and ventricle is insufficient to make them pulsate, although the ventricular ganglia are suf- ficient, when separated from the auricle, to set the ventricle in motion. This explanation is opposed to the fact that if the venous sinus be gradually, instead of suddenly, separated from the auricle, they will still continue to pulsate. Notwithstanding this objec- ' tion, however, it seems to us that this explanation, although very probably it does not represent the whole truth, is to a consider- able extent true, and the cessation of the auricular and ventri- cular movements, after the removal of the venous sinus, is really due, in a great measure at least, to want of motor power. It occurred tons that if this were so, we ought to be able, by stimu- lation of the motor ganglia, to reinduce the cardiac pulsations after they had ceased from ligature of the venous sinus. It is well known that if a single galvanic shock be applied to the ven- tricle when in this state of diastolic quiescence, the ventricle will contract once at each application of the stimulus, but the single pulsation is not succeeded by a succession of rhythmical beats. As warmth has a very powerful effect in increasing the cardiac activity, it seemed probable that the application of warmth to the heart, when in the condition of still-stand thus described, might , so far stimulate its motor ganglia as to allow it to resume its rhythmical pulsations. We therefore induced complete still-stand . in the frog’s heart by applying the ligature in the usual way. On then warming the heart, either by directing upon it a current of . air heated by passing it through a hot glass tube, or by bringing . into its neighbourhood a heated copper wire, we found that the . rhythmical pulsations again commenced, aud continued for two or r three minutes after the time that warmth was applied. The cessation of the movements of the heart, after the removal of the venous sinus, seemed to us analogous to the cessation of , respiratory movement aud of vaso-motor tone after the influence , of the medulla oblongata has been removed by division of the spinal cord at the occiput. It has been found by Prokop Roki- tansky that the movements do not cease completely, after division of the cord, when the animal has been previously poisoned by strychnia, and that both vaso-motor reflex and respiratory move- ments can be reinduced in such animals by strychnia adminis- .