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

  • Henry Hallett Dale
Date:
[1906?]
Catalogue details

Licence: Public Domain Mark

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

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    convert the effect of any dose of adrenaline or ol the strongest stimulation of the splanchnics into pure depression, stimulation of the chorda tympani causes the usual acceleration of blood-flow through the cat’s submaxillary gland, as seen by the rate of hgemorrhage from a small cut vein draining the gland. Under the same conditions stimulation of the 2nd and 3rd sacral roots in the spinal canal caused a marked erection of the penis, not perceptibly different from that obtained before the ergot was given. The inhibitory effect of the vagus on the heart likewise suffered no trace of diminution: indeed, after large doses of ergot the inhibition seemed to be more complete with the weaker stimuli than before. With the secondary coil at 10 cm., for example, I obtained a very partial inhibitory effect from either vagus at the beginning of one experiment. After giving 150 mgms. of chrysotoxin a much more complete effect was obtained with the same strength of stimulus. This difference can probably be explained by removal of tonic accele¬ rator impulses in the true sympathetic. However that may be, the fact of importance is that the cranial and sacral autonomic inhibitory nerves to the heart and arteries suffer no paralysis at any level. The cardio-accelerator effect of adrenaline, as stated above, is not abolished by such doses of ergot as suffice to reverse the effect on the blood-pressure. With larger doses, however, the accelerator myoneural junctions also suffer paralysis, about 200—300 mgms. of active chryso¬ toxin being normally sufficient to complete the effect. There is here no question of reversal: neither by adrenaline nor by electrical excitation of the cardiac branches from the stellate ganglion have I succeeded in producing a slowing of the heart. The effect was, like that on the arteries of the rabbit, a simple progressive abolition of the action of the sympathetic fibres and of adrenaline. 2. The Spleen. The observations were made on cats with the brain pithed. The spleen was enclosed in an air plethysmograph, registration being made by a large Hurthle piston-recorder. A preliminary dose of T mgm. of adrenaline caused the usual rise of blood-pressure and contraction of the spleen. Two successive doses of chrysotoxin, of 50 mgms. each, were then given. Each injection caused a brief contraction succeeded by steady dilation of the spleen : and since the second injection caused no rise of blood-pressure above the level maintained after the first injection, the effects must be attributed to the chrysotoxin itself. The course of
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