Simultaneous Electrograms and Myograms from Isolated Intestinal Segment in Unanaesthetized Dog

Abstract

In a series of dogs, segments of the small intestine 5 to 10 cm. in length were isolated from the remainder of the intestinal tract and transplanted onto the surface of the abdomen. These segments were taken from various portions of the bowel between the upper duodenum and terminal ileum. Continuity of the remainder of the intestinal tract was re-established. When the animals had completely recovered from the operative trauma electrograms were made of the isolated segments. Two electrodes were placed at varying distances apart on the longitudinal axis of the bowel segment and were connected with a string galvanometer. The electrograms obtained were constant in their rate for given segments and reveal some rather characteristic phases. The electrograms persisted after the segment had been completely separated from the central nervous system. They also persisted, although with slight changes in certain phases, whether the segment was visibly active or quiet. This has been discussed more fully elsewhere. 1

Four dogs have been studied to determine the relationship of respiration and of mechanical activity of the bowel segment to the electrogram. Platinum wire electrodes covered with cotton and saturated with normal saline solution were used. The string of the galvanometer was relatively loose, deflecting 2 cm. per millivolt. A pneumograph was so arranged as to record respiratory movements simultaneously with electrograms on the same film. These showed that there was no relationship between respiration and the electrical complexes obtained from the isolated bowel. (Fig. 1.) Balloons were then inserted into the isolated bowel segments and connected to record contractions of the bowel on the same film with the electrogram. A very small balloon was used and the electrodes were placed on the surface of the bowel directly over it.