Abstract
It was thought that a technique of recording the electrical changes in the isolated warm blooded heart would offer possibilities of determining the direct effect of many drugs. The plan of this work is to study (a) the functional changes as recorded by the electromyograms; (b) chemical changes by subsequent analyses; (c) histopathological changes.
Towards this end the following technique was devised and has proved to work satisfactorily in preliminary experiments. Fertile chicken eggs are incubated to the desired stage. The embryos are removed from the shell and pinned out on a paraffin block. The heart is dissected out carefully, leaving a fairly long stalk of great vessels and some tissue. This avoids injury to the auricles and allows for handling. The isolated heart is then placed in a receptacle.
The receptacle used is a small glass dish cemented to an ordinary microscopic slide, which is set on a mechanical stage. The dish is filled about half way with paraffin, to allow for fixing the heart in place.
The electrodes consist of 2 zinc-zinc sulphate cells of simple construction. An ordinary test tube is drawn to a capillary about 3 inches from its mouth. The constricted portion between the capillary tip and body of the tube is bent out at about a 60° angle. The capillary tip is then bent down in the complementary angle at a point where it extends beyond the outer wall of the tube, and cut to leave a tip of a few millimeters. This is done to allow approximation of the two electrodes. A glass slide is cemented to the body of the tube with DeKhotensky for fixation to mechanical stages, by means of which motion is obtained in 3 dimensions.
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