On the tonicity of the heart and arteries / by W.H. Gaskell ; communicated by Michael Foster.

  • Gaskell, Walter Holbrook, 1847-1914.
Date:
1880
Catalogue details

Licence: Public Domain Mark

Credit: On the tonicity of the heart and arteries / by W.H. Gaskell ; communicated by Michael Foster. 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.

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    [From the Proceedings «f the Royal Society, JjF “On the Tonicity of the Ha^ii&^efteries.’’ By W. H. Gaskell. M.D., Trinity College, Cambridge. Communi- cated by Dr. Michael Foster, Prelector of Physiology in Trinity College, Cambridge. Received March 1, 1880. The author has made a lengthened series of observations on the heart of the frog and tortoise, both on the entire ventricle and on the apex, supplied, by the help of Roy’s* tonometer, with saline solutions or with diluted blood (of rabbit, sheep, or bullock). That the artificial blood solutions differ in their action on the apex from the frog’s own blood in degree only and not in kind, and that consequently Bernsteinf is wrong in regarding these fluids as specific stimuli givingrise to rhythmic action, is shown by the following facts. 1. The apex of the frog’s heart brought to quiescence after Bern- stein’s method, will beat spontaneously when the pressure in its cavity is increased by clamping the aortic arches. 2. If while the heart still remains in its natural position within the body, the frog’s own blood be replaced by the artificial blood solution, and the ventricle be then nipped by fine forceps, the apex will remain quiescent for an indefinite length of time. As soon, however, as the pressure in the cavity is increased, the apex commences to contract, and beats as long as the heart is distended by the increased pressure. The conclusions to which the author has been led by his experiments are as follows : — 1. The heart possesses, like the arteries, what may be called tonicity, and the variations in this tonicity play an important part in deter- mining the features of the cardiac beat. The apex, when first tied on to the cannula, the pressure of the blood solution being kept constant at 10 cm. or less, remains quiescent for some time in the position of greatest relaxation. As, however, the blood solution continues to pass through, the lever of the tonometer rises often very appreciably even before the apex begins to beat. This rise, unless otherwise explained, would seem to show that the first effect of the blood solution has been to bring the apex into a condition which is no longer that of greatest relaxation for that particular pressure. Further, in correspondence with this raising of tone of the cardiac muscle by the artificial blood solution, is the alteration in the character of the beat. The first beats, whether natural or artificially produced, which occur while the ventricle is still in a somewhat relaxed or atonic condition in * “ Journ. of Physiology,” vol. i, p. 452. t “ Ccntralblatt f. cl. Med. Wisscnschaften,” 1876, p. 385.