On some physiological actions of ergot / by H.H. Dale.

  • Dale, Henry H. (Henry Hallett), 1875-1968.
Date:
[1906?]
Catalogue details

Licence: Public Domain Mark

Credit: On some physiological actions of ergot / by H.H. Dale. Source: Wellcome Collection.

    12/48 (page 172)
    excitation of the splanchnics with any strength of current which is effective at all. Further injections of chrysotoxin then complete the paralysis, so that any amount of adrenaline—I have used up to 20 mgms. as a dose—and the strongest stimulation of the splanchnic nerves cause a simple fall of pressure. A similar reversal of the sympathetic pressor effect was produced in the dog and the ferret1, but the fall of pressure observed was in neither case so striking as in the cat. The necessary quantity of the ergot preparation was also relatively larger; a dog of about 15 kilograms requiring 10—20 times the amount which would complete the reversal in a cat of 2—3 kilograms. It is of incidental interest to note that, when once the paralytic effect has been produced in the dog, any quantity of adrenaline may be injected without the ordinary danger of heart-failure, attributed by Elliott to intravascular clotting. If Elliott’s conclusion is correct the clotting must be dependent on some action of adrenaline which ergot annuls: for, as we shall see, many of the effects of adrenaline are retained unaltered, so that the substance is not itself destroyed. In the rabbit the fall of pressure with adrenaline was never obtained, the effect of ergot being, in this animal, a gradual weakening and ultimately an approximate abolition of the pressor effect of small doses of adrenaline. Even this required large doses of the drug—about 200—300 mgms. of active chrysotoxin. The fowl is still more resistant to the paralytic action, and with chrysotoxin I never succeeded in producing more than a slight diminu¬ tion of the sympathetic pressor effect. Recently, with a powerful specimen of cornutine giving vaso-motor reversal in the cat in a dose of 1 mgm., I succeeded, by giving 20 mgms. to a cock, in reducing the effect of 0T mgm. of adrenaline practically to nil, though 1 mgm. still gave a fair rise of blood-pressure. Adrenaline, directly applied in 1 in 1,000 solution, then failed to cause contraction of the jejunum. This resistance of the fowl is strongly suggestive in connexion with its special liability to the gangrene associated with ergot poisoning. Some conclusions may be drawn at this stage as to the nature of the paralytic effect on the vascular system. The unaltered efficacy of barium chloride and pituitary extract must first be considered. The importance of the barium effect may be discounted by regarding it as due to a toxic rigor of the muscle fibres. This can hardly be urged in the case of pituitary extract. The effect of this can be repeated a number of times if sufficient 1 Cf. Elliott. This Journal, xxxn. p. 412. 1905.