The two-component stomach: effects of meal particle size on fundal and antral emptying

Using a dual-headed gamma camera and a standardized egg test meal labeled with ^99mTc-sulfur colloid, the quantitative emptying of the total, proximal and distal stomach in five normal subjects was characterized. The same egg meal was given to the volunteers in 3 different forms: homogenized, and as 2.5 mm and 5.0 mm cubes on 3 separate occasions for a total of 15 studies. For the total stomach emptying, the lag phase and half emptying time (T_1/2) obtained using a power exponential model were significantly shorter for the homogenized test meal than for the 2.5 mm and 5.0 mm cubed egg particles; the lag phases were 29±19 min (mean±SD) vs 55±56 (P<0.05) and 64±24 min (P<0.01), the T_1/2s were 71±30 min vs 91±26 (P<0.05) and 104±30 min (P<0.05), respectively. For the proximal stomach, no statistically significant difference was observed among the 3 test meals; the T_1/2s for the homogenized, 2.5 mm and 5.0 mm cubed meals were 65±26 min, 53±18 min and 64±20 min, respectively. For the distal stomach, both the peak activity (%) and time to peak activity (min) were significantly higher for the 2.5 mm cubes (43%, 54 min) and the 5.0 mm cubes (38%, 60 min) than for the homogenized eggs (16.4%, 30 min) (P<0.01). The correlation between the lag phase for the total stomach and the time to peak activity in the distal stomach was excellent (r=0.85, P<0.001 suggesting that the lag phase may correspond to the maximum filling of the distal stomach. These results demonstrate quantitatively that the proximal portion of the stomach is mainly responsible for the receipt and storage of food and the emptying of liquids, while the distal stomach appears to be primarily involved with the processing of solid food before its passage through the pylorus.