A method for long-term recording of intestinal mechanical and electrical activity in the unrestrained rat

A small animal model has been developed to study simultaneous mechanical and electrical activity of the gastrointestinal tract in the conscious unrestrained animal. Mechanical activity is detected using miniaturized half-bridge metal foil strain-gauge force transducers. The conventional lead-wire arrangement has been modified, thereby extending the useful life of the gauge. The electrical activity is monitored by silver/silver chloride bipolar electrodes. The lead wires from the recording units are encased in a metal compression spring and are permanently joined to a ball connector positioned on top of a modified cage. This allows the animal free access to all parts of the cage. The results are monitored using a polygraph chart recorder and stored on magnetic tape for subsequent modified replay or computer analysis. This model provides an inexpensive and reliable method for monitoring gastrointestinal motility in the unrestrained small laboratory animal, enabling more comprehensive studies than have hitherto been possible only with larger species.