Action of Certain Drugs on Isolated Intestinal Transplants

Abstract

By an operative procedure previously described segments of small intestine were isolated from the remainder of the intestinal tract and transplanted onto the surface of the abdomen. 1 By applying electrodes attached to a string galvanometer to the segment, waves of altered electrical potential were obtained. Previous studies have shown that these potential changes probably arise from some cause within the segment itself because when all original connections with the central nervous system have been severed they persist in practically an unaltered form. The two most likely sources of this phenomenon are the intestinal musculature and the intrinsic nervous tissue which consists of the plexuses of Auerbach and Meissner. Gross observations and simultaneous myograms and electrograms have shown that there is a definite time relationship between muscular contractions and the electrograms. 2 However, the waves of altered electrical potential continue when no record of muscular activity can be obtained. In an effort to obtain further information of the nature and origin of the electrograms a series of drugs were administered intravenously and their effects noted. These are briefly summarized here.

Epinephrin was followed by a complete cessation of the myogram within 10 seconds but the waves of altered electrical potential persisted. Alvarez^{3, 4} and his coworkers have noted similar effects of this drug. This may be explained by the stimulating action of epinephrin on the receptive mechanism of the sympathetic system, thus increasing sympathetic inhibition. The persistance of the electrogram does not rule out the possibility of myogenic origin. Physostigmin (0.1 mg. per kg.) was followed within 30 seconds by an increase in degree and duration of the contractile phase of the myogram but no marked change in the electrogram. Atropin was followed by a rapid diminution in the strength of muscular contractions until they became imperceptible, but again the electrograms persisted.