Chemical structure and sympathomimetic action of amines / by G. Barger and H.H. Dale.

  • Barger, George, 1878-1939.
Date:
[1910?]
Catalogue details

Licence: Public Domain Mark

Credit: Chemical structure and sympathomimetic action of amines / by G. Barger and H.H. Dale. Source: Wellcome Collection.

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    living animal. We believe that the association of a pressor action, due to arterial constriction and cardio-acceleration, when the substance is injected into the whole animal, with inhibition of the tone and rhythm of the isolated non-pregnant uterus of the cat, is almost sufficient evidence to warrant the attribution to a substance of an action of the sympathomimetic type. We have, however, in all cases confirmed the diagnosis by observing several of the other sympathetic effects above mentioned. In the case of homologous series and closely related compounds we have usually performed this analytical identification of the action completely in the case of one typical member only, being content in the case of others to observe that the action was of the same general type. It must be understood, however, unless the contrary is specifically stated, that the action of any substance spoken of as sympathomimetic has been proved to be so. As a general quantitative index of the activity of a substance, of which the type of action has been identified as sympathomimetic, we have adopted the effect on arterial blood-pressure. This has obvious advantages in the ease with which it can be observed and measured, and its adoption makes our results to some extent comparable with those of other observers who have used it for this purpose. We shall show, however, that this'method affords only a broad and rough indica¬ tion of the order of activity of the different bases. In the case of closely related bases the relative values 'obtained by different observers differ somewhat widely. The animals used, the mode of anaesthesia employed, and probably less obvious differences of technique, as well as individual variations of response in animals of the same species, all affect the results. We shall show, further, that the indications of relative activities obtained by the blood-pressure method by no means hold good for the action on other organs innervated by sym¬ pathetic nerves. The effect on the blood-pressure is, indeed, so complex that the determination of the relative efficiency of some closely related bases in its production has not much more than a conventional value, until the results are analysed in the light of observations on other sympathomimetic effects. For the comparison of pressor activities we have used decerebrate cats almost exclusively. When other animals were used, or the brain not destroyed, the fact is stated and the anaesthetic mentioned. In most of our experiments the spinal cord was cut at the level of the axis vertebra, the neural arch of the vertebra being removed. Up to this point complete anaes¬ thesia was maintained by ether and chloroform. The brain was then