Human gastric emptying and colonic filling of solids characterized by a new method

Our first aim was to compare ¹¹¹In-labeled Amberlite IR-12OP resin pellets and ¹³¹I-labeled fiber in the assessment of gastric and small bowel transit and colonic filling in healthy humans. Both radiolabels were highly stable for 3 h in an in vitro stomach model and remained predominantly bound to solid phase of stools collected over 5 days [90.5 ± 2.1 (SE)% for ¹³¹I and 87.4 ± 1.4% for ¹¹¹In). The lag phase of gastric emptying was shorter for ¹¹¹In-pellets (30 ± 11 min compared with 58 ± 12 min for ¹³¹I-fiber, P < 0.05). However, the slope of the postlag phase of gastric emptying and the half time of small bowel transit were not significantly different for ¹¹¹In-pellets and ¹³¹I-fiber. Filling of the colon was characterized by bolus movements of the radiolabel (10-80% range, 26% mean) followed by plateaus (periods of no movement of isotope into colon lasting 15-120 min, range; 51 min, mean). Half of the bolus movements occurred within 1 h of the intake of a second meal. Thus ¹¹¹In-labeled Amberlite pellets provide an excellent marker for the study of gastric and small bowel transit and colonic filling in humans. The ileum acts as a reservoir and transfers boluses of variable sizes into the colon, often soon after the intake of a subsequent meal.