Two-dimensional high-resolution motility mapping in the isolated feline duodenum: methodology and initial results

Several types of electrical events occur in the small intestine but their s patial and temporal contributions to overall motility are not clear. In ord er to quantify local motility in greater detail, a new technique of recordi ng and analysing movements at multiple sites was developed. Use was made of isolated segments of feline duodenum superfused in a tissue bath. Multiple marker dots (20-75) were. placed on the serosal surface by applying fine s pots of candle soot in rectangular arrays (1-2 mm dot separation). A digita l video camera was used to record spontaneous movements of the dots for per iods of 10-30 min, After each experiment, 4-6 periods (10-60 s each) of vid eo frames were transferred to a computer (25 fps, 720 x 576 pixels) and the movements of the dots was tracked every 40 ms using custom-made software. Initial results (eight experiments) show that spontaneous motility is remar kably variable., both in space and time. Three types of movement could be d iscerned: (i) periodic, rolling or pendular movements, with a frequency of approximately 15 min(-1) occurring predominantly in the longitudinal direct ion; (ii) twitches, wherein a subset of dots were suddenly displaced longit udinally, and (iii) drifts of most of the dots in a circular or oblique dir ection. All three types of movement occurred throughout every recording ses sion although their relative magnitudes differed greatly from moment to mom ent. Occasionally, it was possible to detect propagated 'contractions' with an apparent velocity of 10 mm s(-1). Immobilizing the preparation at one p oint by inserting a needle through the middle of the array of markers had a negligible effect on the displacements, whereas application of verapamil ( 10(-5) mol L-1) reduced or abolished motility. In summary, we present a new technique to map in detail two-dimensional motility at the surface of the intestine. Initial results seem to suggest that motility at the serosal sur face is not uniform and highly anisotropic.