A SYSTEM TO TELEMETER INTRALUMINAL INTESTINAL PRESSURES FROM MEDIUM-SIZED LABORATORY ANIMALS.

A system for telemetering intraluminal pressure from the small intestine is described. A radio transmitter capsule, calibrating apparatus, and receiving equipment form the essential components. Pressure changes on the flexible diaphragm of the radio transmitter move a ferrite core varying distances within the electromagnetic field of an oscillator coil, thereby causing deviations in the carrier frequency of the transmitter i.e., frequency modulation. The carrier frequency is received by antennae outside the animal and demodulated by a radio receiver adjusted to detect only pressure induced deviations in frequency from the carrier frequency. These frequency deviations are converted to dc voltages which are recorded on a pen recorder and on magnetic tape for computer analysis. The small size of the radio transmitter and its stability following exposure to ionizing radiation make the system suitable for use in studies to determine the effect of radiation exposure on in vivo gastrointestinal motility in beagle dogs or other medium-sized laboratory animals. Author