File:University of Toronto studies. Physiological series. no. 1-98. 1900-28 (1900) (14587553497).jpg

Identifier: universityoftor11univuoft (find matches)
Title: University of Toronto studies. Physiological series. no. 1-98. 1900-28
Year: 1900 (1900s)
Authors: University of Toronto
Subjects: Physiology
Publisher: (Toronto) University Library: Published by the Librarian
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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yman (4) satisfy the facts observed in the differential action of ad-renalin (5). They attributed the two effects, vasodilatation and vaso-constriction to opposite actions according to the state of the muscle—relaxation when tonically shortened, contraction when relaxed. Finally the work of Gruber (6) suggests that the central nervous sys-tem is involved in the dilatation from adrenalin. He found that dosesof adrenalin which caused dilatation in the normal limb of the cat pro-duced constriction when the nerves were cut. In attempting to explain the dilatation from adrenalin in the intestineof the cat and dog we (3) found that if the splanchnics were cut con-striction replaced dilatation. This observation led us into a study ofthe part played by the central nervous system in adrenalin vasodilata-tion. The following investigation is the result. Ether anaesthesia was used in all experiments, except a few in whichanocain was injected. Blood pressure in all except the anocain experi- 353
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356 MECHANISM OF ADRENALIN VASODILATATION 357 0.025 cc. of adrenalin 1 : 1,000,000 caused a fall of blood pressure from125 mm. to 120 mm., while 0.2 cc, 1 : 1,000,000 not only produced afall of blood pressure from 127 mm. to 93 mm., but brought about con-striction in both normal and denervated limbs. However, there isthis to be said about these exceptional cases: the normal limb usuallyeither gives no constriction or else much less constriction as comparedto the denervated limb. So although there may be no positive dilata-tion there must be enough in the normal limb to lesson or else obliteratethe local constrictor effect of adrenalin. The following is a typical experiment of the ten which gave positivedilatation: Cat, weight J.J kgms. (See figs, i and 2) BLOOD PRESSURE CHANGE IN MILLIMETERS OF MERCURY NORMAL LIMB DENERVATED LIMB DOSE OF Dilatation Constriction Dilatation Constriction CC. 1:100.000 c30 a < 0 23Q n 3 0B< s.0 3Q c30E< c0 23Q a 3 i< B.0 2 3D cc. seconds cc. s

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