The physiological action of [beta]-iminazolylethylamine / by H.H. Dale and P.P. Laidlaw.

  • Dale, Henry Hallett, 1875-1968.
Date:
[1910]
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: The physiological action of [beta]-iminazolylethylamine / by H.H. Dale and P.P. Laidlaw. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    that the pressure begins to rise, but the rise soon gives way to a rapid fall. During this fall vigorous but largely ineffective inspiratory efforts occurred, the resistance to air entry being obviously very great. Heart- failure seemed imminent, but recovery soon set in and the blood- pressure again became steady at a rather lower level than that obtaining at the beginning of the experiment. A second injection of 2 mgms. was then given : violent and ineffective respiratory efforts immediately reappeared, during which the blood-pressure fell rapidly and permanently to zero, the force of the artificial respiration pump, which was applied, being insufficient to produce an effective expansion Fig. 10. Rabbit. Urethane. Effect of, A 0-1 c.c. extract of ergot; and B 1 mgr. /3-I. on the blood-pressure. of the lungs. The second rabbit was left for about half an hour under the full influence of urethane before the preparation was begun. Injection of the same doses of the same solution of /9-I. caused, in this experiment, simple rises of blood-pressure. Some temporary increase of resistance to air-entry, with deepened respiration, was manifest, but not sufficient seriously to interfere with the circulation. Larger doses in this rabbit simply caused more prolonged rises of blood-pressure. Fig. 10 shows the effect on the blood-pressure of a rabbit, after pro- longed urethane anesthesia of /S-I. and of an ergot extract having a very powerful stimulant action on the isolated uterus. It seems clear that the uncomplicated effect of /S-I. on the heart and vessels of the rabbit is to cause a rise of systemic pressure. This can be shown by the plethys- mograph to be due mostly to arterial constriction, in which, in this animal, the intestinal vessels share. (Fig. 11.) Unless, however, the effect on the bronchioles be depressed, as by prolonged urethane anaesthesia, this effect is overshadowed by the secondary effects. The sudden and even fatal fall of pressure, produced under such conditions by small doses of the drug, may probably be attributed to the combined