File:American journal of physiology (1898) (14596561549).jpg

Identifier: americanjourna04ameruoft (find matches)
Title: American journal of physiology
Year: 1898 (1890s)
Authors: American Physiological Society (1887- ) American Physiological Society (1887- ). Abstracts of papers presented at the fall meeting American Physiological Society (1887- ). Proceedings
Subjects: Physiology Physiology
Publisher: (Bethesda, Md., etc.) American Physiological Society (etc.)
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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aken.The results are presented in Table I (p. 297). In the experiment of October 14, which is one of those included inTable I, the blood-pressure, which had fallen to about 60 mm. in con-sequence of the preparation of the splanchnic nerves, rose suddenlywithout any apparent cause to about 120 mm. The depressors wereat once stimulated and the pressure fell to about 55 mm. (Fig. i).On repeating the stimulation the blood-pressure fell from 120 mm.to 60 mm. (50 per cent), but after the stimulation the pressure re-turned only to 105 mm., and soon after fell rapidly in such a way asto make a continuation of the experiment imprudent. It seems best 19 290 W. T. Porter and H. G. Beyer. to mention this experiment particularly, although the exceptionalcharacter of the observation unfits it for use as a basis of comparison.So large a fall in blood-pressure, after the preparation of the splanch-nic nerv^es, was not observed again, either before or after their separa-tion from the vasomotor centre.
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111111111 Figure 1. — October 14, 1S99. A curve of blood-pressure in the carotid arteryrecorded by a mercury manometer. The middle line marks the time in seconds.The lowest line marks the atmospheric pressure ; it was drawn by the writing pointof an electro-magnetic signal in the primary circuit of one of the stimulating induct-oriums. The broad black band records the simultaneous stimulation of bothdepressor nerves. The blood-pressure fell from about 120 mm. to about 55 mm. (54per cent). It appears from Table I that in animals in which a thread hasbeen placed around both splanchnic nerves the stimulation of thedepressor nerves causes a fall in blood-pressure usually of from 35to 40 per cent. With this must be compared the effect of depressorstimulation when the splanchnic nerves are separated from the vaso-motor centre and the blood-pressure maintained near the normallevel. Relation of Depressor Nerve to Vasomotor Centre. 291 The Effect of Depressor Stimulationafter the separation

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