Strophanthus hispidus, continued : pharmacological action. (Abstract) / by Thomas R. Fraser.

Date:
[1889?]
Catalogue details

Licence: Public Domain Mark

Credit: Strophanthus hispidus, continued : pharmacological action. (Abstract) / by Thomas R. Fraser. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    electric stimulation of its motor nerve fails to cause any effect. After the twitching contractions have ceased, the motor nerve regains its influence; and the contractions of the entire muscle, which are now produced by stimulating the nerve, illustrate the condition of increased tonicity produced by Strophanthus. The muscle curve is altogether different from the normal curve. The muscle contracts actively, but, after having contracted, it relaxes with great tardiness; and it is only after several revolutions of a rapidly revolving cylinder that the curve gradually falls to the abscissa. [Curves were shown.] When Strophanthus is administered by subcutaneous injection to a frog, one of whose muscles, without otherwise deranging its normal relations, is attached to a lever writing on a revolving cylinder, similar changes in contractility are observed, but they are less in degree. [Curves were shown.] Owing partly to the circumstance that a larger quantity of any substance introduced into the blood is in any given time conveyed to the heart than to any other individual organ or structure of the body, the action of Strophanthus is exerted with the greatest energy and activity upon the heart. With very minute doses, its contractions are rendered slower and more perfect and com- plete ; and with larger doses, the diastolic dilatation of its chambers is reduced until dilatation disappears altogether, and the heart ceases to beat because its muscle can no longer relax. The condition of the muscle becomes the same as that of the other striped muscles under the influence of large doses. It is hard, non-contractile under stimulation, and acid in reaction,—the condition of true rigor mortis having been produced as the ultimate stage in the sequence of events in the pharmacological action of Strophanthus. These changes occur even although all the nerve connections of the heart are severed, or the vagus nerve is paralysed by the previous adminis- tration of atropine. The power of an extremely minute quantity of Strophanthus to produce these effects on the heart was illustrated in a series of experiments, in which an attempt was made to determine the minimum quantity required to paralyse the frog’s heart. The heart was attached to an apparatus allowing it to pump from a reservoir a fluid which sustained its nutrition for many hours,