On the action of ergotoxine : with special reference to the existence of sympathetic vasodilators / by H.H. Dale.

  • Dale, Henry Hallett, 1875-1968.
Date:
1913
Catalogue details

Licence: In copyright

Credit: On the action of ergotoxine : with special reference to the existence of sympathetic vasodilators / by H.H. Dale. 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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    of an extract of ergot, which was being tested, and which contained approximately 1 mgm. of ergotoxine, caused a large rise of blood- pressure. As this was subsiding 4 mgms. and then 5 ragms. of ergo- toxine phosphate were injected, making about 10 mgms. in all. Each of these later doses caused a temporary dip in the curve, which other- wise fell smoothly, When it had reached 110 mm. and was declining more slowly, 0T mgm. of adrenine was injected, and produced the practically pure vasodilator fall of pressure to below 80 mm. illustrated in the lower curve of Fig. 1. The fact that cardio-acceleration slightly Fig. 1. Pithed cat: carotid blood-pressure. Upper curve shows effect of 0-025 mgm of adrenine before, lower curve that of 0-1 mgm. of adrenine after 10 mgms. of ergo- toxine. anticipates the vasodilatation, and survives it for a considerable period, accounts for the small initial pressor peak, and for the long, low rise of pressure, which follows the marked fall. The line drawn at the 120 mm. level is common to the two curves, which have been mounted in vertical series for comparison. It is hardly necessary to emphasise the fact that a critical level of arterial tension, above which adrenine causes vasodilatation, and below which it causes vasoconstriction, will not account for the reversal here exhibited. With smaller doses of ergotoxine, such as those used by Cannon and Lyman, the reversal of the adrenine effect is incomplete. Under 19—3