A miniature transducer for recording intestinal motility in unrestrained chronic rats.

An extraluminal strain gage force transducer has been developed for recording gastrointestinal motility in small animals such as rats. Two commercial strain gages are bonded and wires attached to form half a Wheatstone bridge. The device is placed between silicone sheeting and prepared for implantation. As many as six implanted transducers can record simultaneously contractions and tone variations of circular or longitudinal gastrointestinal muscles. The transducers have been implanted in more than 20 rats, with some units lasting up to 4 mo. Furthermore, good relationships exist between intraluminal pressure waves registered by a small intraluminal balloon and gut contractions registered by the transducer. The transducers are a useful and accurate tool for rodent gut motility studies.