The isolated hearts of guinea pigs sensitized to horse serum have been shown to react characteristically upon exposure to small amounts of antigen. The cardiac rate is temporarily accelerated and transient alterations in amplitude of contraction are to be observed. Electrocardiographic abnormalities, previously recorded by remote leads during anaphylactic shock in the intact animal, have been recorded by direct leads from the isolated perfused hearts of sensitized animals during this reaction.
An additional effect of anaphylaxis in the isolated heart of the guinea pig is reported: a striking reduction in the rate of flow through the coronary vessels.
The anaphylactic reaction of the isolated heart of the guinea pig has been compared with the action of histamine upon the same preparation and the effect of atropine upon each has been observed. The implications of certain quantitative differences in the influence of atropine upon these reactions are discussed.