The fall of blood pressure resulting from the stimulation of afferent nerves / by Reid Hunt.

  • Hunt, Reid, 1870-1948.
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: The fall of blood pressure resulting from the stimulation of afferent nerves / by Reid Hunt. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    ductivity of nerve fibres, in which he shows that, if a portion of the sciatic is cooled to near 0° C, and stimulated peripherally to this part, the result is a reflex fall of pressure. He suggests that there are depressor as well as pressor fibres present and that the former do not lose their power of conducting impulses at a low temperature as readily as do the latter. Part II. The Afferent Fibres by which a Fall of Pressure is produced. Method of experimenting. In addition to the method of cooling, other methods were employed to produce a reflex fall of blood-pressure ; these will be described in their proper places. The animals used were cats, dogs, and rabbits and they were in all cases anaesthetized, by some method. The vagi were cut in most cases. The blood-pressure was taken from the carotid and recorded in the usual manner. In most of the experiments the nerve stimulated was the sciatic, but sometimes the saphenous, ulnar, median or anterior crural and occasionally other nerves were used. I shall consider first the stimulation of the sciatic, and then compare with these results the effects produced when the other nerves were stimulated. 1. Effect of Cooling. The nerve was cooled in the manner described by Howell1, viz., by drawing the central end of the divided nerve through the transverse tube passing through the angle of a V-tube ; cold alcohol was circulated through the V-tube and so around the transverse tube containing the nerve. In this way the nerve could readily be cooled to 0° C. or lower. No attempt was made to determine the exact temperature of the nerve; the temperature given is that of the alcohol at the angle of the V-tube and as Howell showed, that of the nerve probably did not vary from this by as much as 1° C. The nerve was stimulated an inch or two below the tube with a weak interrupted current from a Du Bois Reymond coil. As the result varies with the kind of anaesthesia employed, it will be best to consider the different cases separately. Brain Compression. This was produced by trephining, care being taken not to rupture the dura mater, and then carefully pressing a sponge or bandage, moistened with a -6°/o solution of sodium chloride, into the cavity of the skull till anaesthesia was complete. Rabbits did 1 Howell. Op. cit. p. 300. 26—2