Some observations on vaso-motor reflexes / by Swale Vincent and A.T. Cameron.

  • Swale Vincent
Date:
1914
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Licence: In copyright

Credit: Some observations on vaso-motor reflexes / by Swale Vincent and A.T. Cameron. 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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    Section IV., 1914 [267] Trans. R.S.C. £ Some Observations on Vaso-motor Reflexes. By Swale Vincent and A. T. Cameron. (From the Physiological Laboratory, University of Manitoba, Winnipeg.) (Read May 27, 1914.) The present investigation was suggested by the conflicting results obtained by our senior class of students in trying to obtain the results described in the majority of text-books on stimulation of the central end of an afferent nerve, and by what seemed to us an inexplicable contradiction frequently met with, between the effect of stimulating the cut central end of a sensory nerve, and the effect of stimulating the terminals of such a nerve, as for example, in the skin. Insufficient attention has been paid by previous investigators to the specific pharmacodynamic effect of the anaesthetic employed. It seems to have been assumed by most workers that a standard condition of the animal should be aimed at. in which disturbing in- fluences due to reflex muscular spasms and reflex respiratory move- ments were as far as possible eliminated. Such an object is undoubt- edly desirable from many standpoints, but has in our opinion the supreme disadvantage that the specific action of the anaesthetics concerned is disregarded. In experiments with dogs the majority of observers seem to have employed ether as an initial anaesthetic followed by morphia, and frequently curare. We have found no de- tailed account of what happens in the record of the vaso-motor re- flexes if the animal be simply anaesthetised with ether. We have considered that this problem should not be shirked, especially as such a condition is one very frequently met with in surgical procedure upon the human subject. The problem of the vaso-motor reflexes is of course intimately connected with that of shock, but with the latter subject itself we do not propose to deal. From a large number of experiments on dogs, cats, and rabbits we are led to the following conclusions: When an animal is deeply under the influence of ether, it is fre- quently impossible to obtain any vaso-motor reflexes whatever. When anaesthesia is fairly complete the effect of stimulating the central end of the cut sciatic nerve is sometimes a distinct rise. As the effect of the anaesthetic begins to pass off, the rise is followed by a more or less