Muscarinum

Volume I — Main text

Muscarinuni^ — An alkaloid obtained from Agaricus muscanuSf and also prepared artificially. Its formula is CgHujNOg.HgO.

I, Provings. — I. RiNGER and Morehead experimented on four men, giving gr. \ or more to each hypodermically. Three of their patients were delicate and anaemic ; the fourth had slight fever from some obscure cause, though his pulse was not quickened. Dr. Ringer presents their results as follows :

a. Perspirathn, — Sweating occurred in eleven out of the thirteen experiments. Half a grain always made it free, whilst large doses — as gr f and i — ^rcndered it very abundant, indeed, it was quite as free as the perspiration excited by gr \ — h of pilocarpine. Sweat stood in large drops on forehead after larger doses, nightdress became soaked and skin felt sodden. In one man only was perspiration absent, salivation taking its place. Sweating began in 3 — 15 m., occurring earliest after larger doses, and lasted for \ — ik h. Reaction of sweat in 6 cases was neutral in 4, alkaline in 2.

h. Salivation occurred in 9 experiments, in 3 slight^ in rest free or profuse i began in 2 — 15 m., lasted for 20 — 80 m.

€* Lachrymation occurred in 8 cases, amounting in some merely to suffusion of eyes, but generally tears trickled down face, so that patient was obliged to wipe eyes. Began 6 — 10 m., lasted 20 — 30 m.

d. Purgation, — In 2 instances drug excited inclination to stool ; in 4 experiments on same man it produced a loose motion, one of a greenish colour, though bowels had been opened naturally a short time before* This effect followed in 10 — 20 m.

e. Pulse in one of the four men was always very quick, in other three natural. In latter little change occurred^ in one experiment only rate falling by 10 — 16 beats. Quick pulse was reduced from 120 to 80 or 6o* Larger doses rendered pulse softer and more compressible.

/, Respiration, — Unaffected in every experiment.

g. Eyes, — Pupils always (15 m.) contracted, often considerably; vision unaffected. Applied to eyes muscarine causes wide dilatation of pupil, beginning in 15 — ^45 m.,and continuing about 24 h. Sight here also little affected.

In 3 experiments on one man larger doses induced vomiting once, nausea once. In 5 experiments parients were obliged to pass urine in 9 — 15 m, after injection, and 2 complained of supra- pubic pain. In 5 drug produced a frequent hacking cough. In no case did headache or other nervous symptoms occur. {Handbook of Therapeutics^ 10th ed,, p. 502.)

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dM flic came of the cnntwn 4oei aoc fe ta dbe cafiiac Seedoo of the lagi h» bo dfect i^oo Aa mcdoii of the heart earned hjr mmc^ tfcerefere the inhflwiniy otgpni icatfu^ in die h^n itself ape ftfofigtf excited by the dn^ , and ihci eamtexncnc t$ powetfid enough to couotexacr aQ the cootractfle power of the heart. (It k the»e tame inhibitory orpaa which are faralped bj atropine.) Thii ijifloeiiee of muse, must produce an inidal retaidatkiii of the hcutftroke.

d. In the early stage of the action of miisc. rcspfradoo » more frequent ^nd laboured than in the nattiral coaditioo i later oa there is a steady diminution of its frequency, till at last it ceases altogether. These symptoms of the respiratory apparatus proceed from an initial excitement and subsequent paralysisof the central organ in the medulla oblongata which governs respiration.

/. The blood -vcfisels are constricted for a short time in the outsifl of mufc. action, and afterwards dilated. The vascular dilatation, coaM bincd with the diminished frequency of the cardiac pulsations, causes a decrease of blood pressure, amounting sometimes to one*third of the total amount.

/! The flow of saliva which attends muse, poisoning is the con sqg qucnce of an exciting influence exercised by muse, upon the peripheiJ^ ■iXtrcmitics of the secretory nerves ; at least we are led to this concluniion by the circumstance tnat section of these nerves does not aliect th^ secretion of saliva, jM

}F. Krcnchal has published {Arch.f, Ophthalm.^xx^ I, 135) a vcr^ 00a rc|K)rt (jf the changes in vision produced by muse* Even small oiei lead to disturbances in the accommodating power, which arc charicteriacd as ** accommodation convulsions/ With somewhat larger doses a not very marked myosis sets in, dependent on excitement of the sphincter iridis itself, or on that of the oculo-motor nerve which

governs it. The hypothesis of paralysis of the dilator puptllae or of the sympathetic nerve connected with it is inadmissible, {Ibid J)

1. Schmiedeberg had noticed that intense dyspnoea was one of the most marked symptoms produced by muse. He had not^ however, attempted to explain it. He had observed that during the dyspnoea the arteries contained very little blood, and when cut across bled hardly at alL Desiring to ascertain the causation of this, Dr. Brunton thoroughly narcotised a rabbit with chloral, commenced artificial respiration, and opened the thorax. All was proceeding quite naturally until he introduced a httle muse, into the jugular vein, " At once everything changed. The lungs became blanched, the 1. side of the heart small, the r, side swelled up, and the vena cava became greatly distended.*' A little atropine restored the normal state of things, (Lauder Brunton, Brit. Med. Joum.^ 1874^ i^ ^^7-)

2. a, Prevost found action of muse, on heart unmodified by destruction of nervous centres or by curare. There was no change in breathing in the frogs he experimented on, but in higher animals a violent dyspncea was induced. He found even a feeble dose produce abundant salivation and lachrymation \ former occurs quite as much after section of lingual or removal of superior cervical ganglion. Muse, excites the vermicular contractions of the intestines ; he has seen hernia of the stomach drawn in under its influence. {Ga%. Med, de Parity 1874, p. 243.)

b. Same experimenter has subsequently found that the hepatic and pancreatic secretions are increased by it, but the renal diminished. (Comptes rendus de PAcad, de Med.^ Aug. 10, 1876.)

1. Ringer and Morehead find that if the intra-cardiac inhibitory centre (sinus venosus) is removed and muse, is then applied to the ventricle, it weakens and paralyses the heart, acting apparently on both the cardiac excito*motory apparatus and the muscular substance itself, {Journ. o/Phys.j ii, 234, and Pract,^ xxvi, 4. In Journ. of Phys,y iiij 59, Gaskell confirms direct action on muscular substance.)