The variability of the incremental postprandial portal vein flow response is partly caused by a relationship between fasting flow rate and phase activity of the migrating motor complex

Results from studies on portal flow rate (PFR) have demonstrated a considerable intra- as well as interindividual variability of the incremental integrated response (IIR). We hypothesized that part of the variation of the IIR might be related to variability of the fasting PFR caused by a relationship between PFR and characteristics of the migrating motor complex (MMC). We examined 12 healthy men and PFR was recorded by using the percutaneous colour Doppler technique. Gastric emptying (GE) was determined by scintigraphy and the meal consisted of an omelette of 100 g (1400 kJ; 60% fat, 20% protein, 20% carbohydrates) tagged with 99mTc sulphur colloids followed by 150 ml water mixed with 111In DTPA. The design included recording of PFR in phase II as well as in phase III of the MMC. Meal ingestion took place in the following duodenal phase I. Postprandial recordings of GE and PFR were performed at 10 min intervals for the following 2 h. Median (95% confidence limits) amount of solid emptied at 120 min was 68% (59-81%). PFR in phase III was significantly higher than in phase II (1.56 l/min (1.35-1.93 l/min) vs 0.96 l/min (0.84-1.12 l/min), P< 0.001). PFR increased after the meal and a peak flow of 2.19 l/min (1.58-2.46 I/min) was recorded 10 min after ingestion (P< 0.01 vs phase III). Based on these characteristics a difference in IIR is to be expected, and the calculations revealed that IIR is considerably higher in the phase II series than in the phase III series (50 l/min x 120 min (8-90 l/min) vs -26 l/min x 120 min (-55 to 1 l/min), P< 0.001). In both series a weak but significant inverse relationship was demonstrated between amounts emptied during a 20-min period and the corresponding IIR (n = 72; r = -0.27, P< 0.05 (III); r = -0.29; P< 0.05 (II)). We conclude that fasting PFR is related to phase activity of the MMC and characteristics of the postprandial IIR depend upon MMC activity at the time of recording of the fasting value. Future studies on PFR need to be performed with phase related recording of fasting flow and meal ingestion in relation to preselected characteristics of the MMC.