Two lectures on the connection between the chemical properties and the physiological action of active substances; and the antagonism between the action of active substances. Delivered before the Royal College of Physicians, Edinburgh, on the 19th and 26th April, 1872 / by Thomas R. Fraser.

Date:
1872
Catalogue details

Licence: Public Domain Mark

Credit: Two lectures on the connection between the chemical properties and the physiological action of active substances; and the antagonism between the action of active substances. Delivered before the Royal College of Physicians, Edinburgh, on the 19th and 26th April, 1872 / by Thomas R. Fraser. 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.

    16/40 (page 16)
    r6 to imagine a more decided modification in the action of any substance than is produced by the change of chemical constitution resulting from the addition of iodide or sulphate of methyl to strychnia. The striking characteristic of the action of strychnia is the great and uncontrollable ac- tivity of the muscular system ; that of curara, of iodide and sulphate of methyl-strychnium, and, as we also found, of other similarly modified alkaloids, is the flaccid and motionless condition caused by the impos- sibility of exciting muscular action through the nervous system. So opposite are their effects, that many physiologists look upon curara as a powerful counter-agent to strychnia, while physicians have employed it in the treatment of strychnia-poisoning and of tetanus. It is cer- tainly remarkable that so thorough a change of physiologjical action should be produced by this simple change of chemical condition. The other vegetable alkaloids examined, all possess, though in vary- ing degrees, the same peculiar spinal-stimulant action as strychnia, Brucia and thebaia exert this action with great ener^; codeia and morphia with somewhat less power ; and nicotia, atropia, and methyl- conia, in a still slighter degree, though quite obviously. The result of the combination of each of them with a salt of methyl being, as in the case of strychnia, to change their chemical constitution from that of nitrile bases with triatomic nitrogen, to stable ammonium bases with pentatomic nitrogen; and the change of physiological action following this change of chemical constitution having been found to consist of a removal of spinal-stimulant action and addition of paralysing action restricted to the terminations of the motor nerves, it is unnecessary to give any further details of the results of our experiments. The im- portant general fact which they indicate is, that a change of chemical constitution, even when it is of a simple kind, may produce a very essential change in physiological action; and, although they are perhaps as yet insufficient to warrant any positive assertion, they render it ex- tremely probable that all the stable ammonium bases have a curara- like action. Every such compound that has as yet been examined has been found to possess this action. To the list of those which I have mentioned may be added chloride of oxethyl-stryclmium—recently stu- died by Dr. VaiUant—and iodide of tetra-ethyl-phosphonium—which has formed the subject of a careful investigation by Dr, Vulpian—both salts of ammonium bases, and both found to possess a powerful action on the terminations of the motor nerves. I am anxious, however, to guard against conveying the impression that the compounds of pentad nitrogen act simply as neiwe-paralysers