ACTION OF SYMPATHOMIMETIC AMINES IN CYCLOPROPANE, ETHER AND CHLOROFORM ANESTHESIA

¹ From the Departments of Physiology and Anesthesia, University of Wisconsin Medical School, Madison

By using an intravenous dose of 0.01 mgm. adrenalin per kilogram it may be shown in the dog that cyclopropane anesthesia greatly enhances the activity of adrenalin on the automatic tissue of the heart. In controls adrenalin produces only escape phenomena but under the anesthetic multifocal ventricular tachycardia occurs in practically all experiments. Adrenalin is therefore contraindicated in cyclopropane anesthesia.

By using doses approximately equal to 0.01 mgm. of adrenalin in blood pressure raising power it was found that the following amines in cyclopropane anesthesia act on the ventricular automatic tissue similarly to adrenalin; arterenol, epinine, kephrine, and cobefrine.

In the same way it has been found that ephedrine, propadrine, benzedrine, paredrine, synephrine and neosynephrine do not in comparable dosages exert such effects in cyclopropane anesthesia. With the exception of neosynephrine they do, however, markedly accelerate the sino-auricular rate. In the dog under cyclopropane, neosynephrine is the sympathomimetic amine most favorable to the heart.

In ether anesthesia neither ephedrine, arterenol, cobefrine or neosynephrine produced ventricular tachycardia. Presumably then ether does not sensitize the heart to any of the common types of amines. They all did increase the sino-auricular rate with the exception of neosynephrine.

Under chloroform some cardiac sensitization was shown to cobefrine and arterenol, less to ephedrine and none to neosynephrine.

Premedication with sodium barbital, amytal or nembutal gave no protection against cardiac sensitization from cyclopropane.

Cyclopropane sensitizes the ventricular automatic tissue to those primary and secondary sympathomimetic amines having 3,4 hydroxyl groups on the benzene ring.

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