EFFECT OF FAT PRELOAD ON GASTRIC MYOELECTRICAL ACTIVITY IN NORMAL HUMANS

The aim of this study was to investigate the effect of fat preload on gastric myoelectrical activity in normal humans. The study was performed in 10 normal subjects (five males, five females) fasted for 6 h or more. Gastric myoelectrical activity was recorded using surface abdominal electrodes. In the study session the subjects ingested a 40-g liquid fat meal (2 oz of lipomul) after a 30-min baseline recording. A test meal (225 kcal beef stew) was then consumed 15 min after drinking the lipomul, and the recording was continued for 2 h after the test meal. The control session performed on a separate day followed the same procedure except that the lipomul was replaced by 2 oz of water. The order of the study and control sessions was randomized. The cutaneous recording of gastric myoelectrical activity (electrogastrogram or EGG) was digitized and subjected to computerized quantitative data analysis. The peak power and the corresponding frequency of the EGG during every 15-min time interval were computed using spectral analysis. Student's t-test was applied to determine the effect of fat preload on the surface recording of gastric myoelectrical activity. It was found that: (I) the power of the 15-min EGG at the dominant frequency immediately after fat preload was significantly lower than that of the baseline EGG (P = 0.01); (2) the postprandial power increase of the EGG at the dominant frequency was significantly lower with fat preload than with placebo preload (P = 0.002); (3) the dominant frequency of the EGG was not affected by fat preload. It was concluded that fat preload significancy decreases the power of the EGG but does not affect the frequency of the gastric slow wave.