Experiments on the isolated mammalian heart to show the relation of the inorganic salts to the action of the accelerator and inhibitory nerves / by W.H. Howell and W.W. Duke.

  • William Henry Howell
Date:
[1906?]
Catalogue details

Licence: Public Domain Mark

Credit: Experiments on the isolated mammalian heart to show the relation of the inorganic salts to the action of the accelerator and inhibitory nerves / by W.H. Howell and W.W. Duke. Source: Wellcome Collection.

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    circulating the Ringer’s liquid. We found it more advantageous, however, to so perform the operation as to keep the heart beating until the Ringer’s solution was turned on. In this way the heart continued to beat without interruption and fibrillary contractions did not appear. Our method was as follows. The animals used were cats, since it was found that the heart of this animal beats more certainly on the artificial circulation than that of dogs. We had in fact no failures with the heart of this animal. The cats were anesthetized with ether. The upper portion of the sternum was resected, the internal mammary arteries were ligated, artificial respiration was established and the chest was then widely opened on both sides. The brachio-cephalic artery was clamped close to the aorta and the inflow cannula for the artificial circulation was inserted. The left subclavian was then ligated at the level of the annulus of Vieussen and a loose ligature was laid round the aorta just beyond the origin of the left subclavian. The aorta was opened beyond this ligature, and the artificial circulation was turned on through the brachio-cephalic. After running for a few minutes, to wash out the blood, the aortic ligature was tied and the inferior vena cava was opened widely near the auricle. The heart was then beating upon the Ringer's mixture, and while this was circulating the accelerator nerve was prepared for stimulation, the pericardium was opened freely, and levers were attached to the left auricle and the right ventricle to record their movements. The accelerator nerve of the left side was used in all cases. Most observers state that the accelerator of the right side is more effective, but for our purpose the nerve on the left side was more convenient and it was found to give in all cases very marked accelera- tion and augmentation. As described by Boehm! the large stellate ganglion in the cat gives off the two nerves forming the annulus, and close to the origin of the one which runs ventral to the subclavian sends off also a large branch, the nervus accelerans, or nervus cardiacus e ganglio stellato, toward the heart. A third smaller branch arises in some cases from the ganglion close to the two mentioned and runs toward the heart along the subclavian artery. These three branches, 1, 2 and 3 in the accompanying sketch (Fig. 1), were usually stimulated together, since each of them might contain accelerator or augmentor fibres and they arise so near together that it is convenient to lift them on the electrodes in a bunch. In some cases branch 3, the nervus accelerans proper, when it happened to be well developed, was stimulated alone. The individual animals differed somewhat in respect to the size of this 1R. Boehm. Arch. f. exp. Pathol. u. Pharmakol, rv. p. 255. 1875.
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