RELATION BETWEEN GASTRIC-EMPTYING RATE AND RATE OF INTRALUMINAL LIPOLYSIS

The variable gastric emptying rate of a test meal is one of the major problems in evaluating accurately gastrointestinal physiological funct ions beyond the stomach. The aim of this study was to evaluate the eff ect of the gastric emptying rate on the rate of intraluminal Lipolysis . Thirty four subjects without pancreatic disease (21 with a normal ga stric emptying and 13 with a known slow gastric emptying) and 14 subje cts with pancreatic disease (four without and 10 with pancreatic insuf ficiency) were studied using a dual labelled breath test. The test mea l consisted of one egg, 60 grams of white bread, 10 grams of margarine , and 150 ml of water (350 kcal). The egg yolk was labelled with 91 mg of C-13-octanoic acid, the margarine was labelled with 296 kBq of dis tearyl-2-C-14-octanoyl-glycerol. Breath samples were taken every 15 mi nutes during six hours and analysed for (CO2)-C-13 and (CO2)-C-14 cont ent. The gastric emptying rate of the meal was evaluated by the gastri c emptying coefficient, the half emptying time, and the lag phase; the rate of intraluminal lipolysis was evaluated by the six hours cumulat ive (CO2)-C-14 excretion. Despite a clear distinction in the rate of i ntraluminal lipolysis, no difference could be detected in gastric empt ying rate of the test meal between subjects without and with pancreati c insufficiency, intraluminal hydrolysis was the rate limiting process in fat assimilation; in patients without pancreatic insufficiency, ho wever, gastric emptying could be rate limiting. Therefore, patients wi th known slow gastric emptying, displayed a significantly decreased ra te of intraluminal lipolysis compared with normal controls. This decre ase could be corrected for accurately using a correction factor based on the gastric emptying coefficient. In conclusion, the combined C-13- octanoic acid and C-14-mixed triglyceride breath test permits the meas urement of gastric emptying rate and intraluminal lipolysis simultaneo usly in a minimally invasive way. Correction of intraluminal lipolysis rate for gastric emptying rate of the given test meal permits evaluat ion of fat assimilation rates in a physiological way regardless of gas tric emptying disorders.