The physiological action of drugs : an introduction to practical pharmacology / by M. S. Pembrey, and C. D. F. Phillips.

Date:
1901
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Licence: In copyright

Credit: The physiological action of drugs : an introduction to practical pharmacology / by M. S. Pembrey, and C. D. F. Phillips. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    Experiment LVIII.—The Effect upon Muscle and Nerve.— Two muscle and nerve preparations are made, and their ex- citability is determined; the nerve of the one (A) and the muscle of the other (B) are placed in a watch-glass filled with 1 per cent, solution of atropine sulphate in normal tap-water saline. From time to time the excitability of the preparations is determined, but little or no change will be observed even after the tissues have been exposed to the drug for fifteen minutes. Very large doses of atropine will paralyse the terminations of the motor nerves. There is a marked contrast, therefore, between atropine and curare; small doses of the former paralyse the vagus, whereas large doses of the latter are needed to produce that effect; small cpiantities of curare paralyse the terminations of motor nerves in voluntary muscle, but very large doses of atropine must be applied before similar effects obtain. (See “ Curare,” p. 5 5.) Atropine dilates the pupil of the eye by paralysing the terminations of the motor oculi.1 Cocaine Cocaine, C..H NO,, is an alkaloid obtained from the leaves of 1< -I 4 cocoa (Erythroxylon coca). Its hydrochlorate, C17HO]N04'HCl, is used in medicine ; it is a colourless, crystalline substance readily soluble in water, alcohol, and ether. Experiment LIX.— The Effects of Poisonous Doses.—Under the back of a brainless frog are injected 5 minims (0’296 c.c.) of a 1 per cent, solution of cocaine2 in normal tap-water saline. The excitability of the central nervous system will be rapidly depressed, and in a few minutes the frog will be completely paralysed. No reflexes will be present, but the heart will con- tinue to beat for some time. Death generally occurs within an hour of the injection. Smaller doses, 1 to 2 minims, will produce at first an increased excitability, lasting for a few minutes, and then 1 This effect can be shown by placing a few drops of the solntion of atropine sulphate between the eyelids of a rabbit. The dilatation of the pupil thereby produced can be antagonised by physostigmine, muscarine, and pilocarpine. See pp. 75 and 92. 2 Cocaine hydrochlorate.
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