Effects of ingestion of carbohydrate, fat, protein, and water on the mesenteric blood flow in man

Transcutaneous Doppler ultrasound was used to measure superior mesenteric artery blood flow in 12 healthy volunteers in the fasting state and serially for 1 h after the ingestion of isocaloric and isovolaemic carbohydrate, fat, and protein liquid meals. The superior mesenteric artery blood flow increased significantly within 5 min of the end of each meal. The maximal responses were not significantly different but were reached at different times: carbohydrate, 64% at 15 min; fat, 60% at 30 min; and protein, 57% at 45 min. The response to the fat meal was significantly slower than the response to the carbohydrate, and the response to protein was slowest of all. In a further group of 20 fasted normal subjects no significant change in superior mesenteric artery blood flow occurred after drinking 400 ml of distilled water at room temperature. In seven of these subjects, drinking 400 ml of distilled water at 4 degrees C also did not affect mesenteric blood flow. These results indicate that the chemical nature of the meal and not the volume per se is a significant factor determining postprandial mesenteric hyperaemia.     

Effects of Ingestion of Carbohydrate,Fat, Protein,and Water on the Mesenteric Blood Flow in Man

Transcutaneous Doppler ultrasound was used to measure superior mesenteric artery blood flow in 12 healthy volunteers in the fasting state and serially for 1 h after the ingestion of isocaloric and isovolaemic carbohydrate, fat, and protein liquid meals. The superior mesenteric artery blood flow increased significantly within 5 min of the end of each meal. The maximal responses were not significantly different but were reached at different times: carbohydrate, 64% at 15 min; fat, 60% at 30 min; and protein, 57% at 45 min. The response to the fat meal was significantly slower than the response to the carbohydrate, and the response to protein was slowest of all. In a further group of 20 fasted normal subjects no significant change in superior mesenteric artery blood flow occurred after drinking 400 ml of distilled water at room temperature. In seven of these subjects, drinking 400 ml of distilled water at 4°C also did not affect mesenteric blood flow. These results indicate that the chemical nature of the meal and not the volume per se is a significant factor determining postprandial mesenteric hyperaemia.     

Intestinal phase of superior mesenteric artery blood flow in man.

Duplex ultrasound was used to investigate superior mesenteric artery haemodynamics in humans in order to study the contribution of the small intestine to the postprandial splanchnic hyperaemia, and to determine the relative potencies of the major food components in the postprandial mesenteric flow response. Duplex parameters of vessel diameter, mean velocity, and volume flow were determined serially in the basal state and after stimulation. Flow parameters were significantly (p less than 0.05) increased after liquid and solid oral meals. Modified sham feeding did not alter mesenteric blood flow. Intestinal perfusion of an isocaloric liquid test meal induced flow increases comparable with oral intake. Superior mesenteric artery blood flow also significantly (p less than 0.05) increased after isocaloric and iso-osmolar loads of intraduodenal carbohydrate, fat, and protein meals. Responses were similar after the test meal, fat, and protein, but were significantly (p less than 0.05) less for carbohydrates. Different osmolar loads of saline did not affect flow responses. We conclude that the intestinal phase is the major regulator of the postprandial mesenteric blood flow response in healthy humans and that the chemical nature of food determines the mesenteric response pattern.     

Effects of meal composition on gallbladder and gastric emptying in man

Cholecystogastric scintigraphy, utilizing [^99mTc]HlDA to label the gallbladder contents and [¹¹¹In]DTPA to label different meals, was utilized to determine the relationships between gallbladder and gastric emptying after meals of differing composition. Gallbladder emptying was determined in response to a multicomponent meal and to monocomponent fat, carbohydrate, and protein meals and in response to isotonic and hypertonic dextrose and isotonic and hypertonic saline. Also, the gallbladder emptying responses to equivalent multicomponent solid and liquid meals were compared. Significant gallbladder emptying was observed in response to the multicomponent meal and the monocomponent fat, carbohydrate, and protein meals. The most rapid and complete gallbladder emptying was seen with the multicomponent meal and the monocomponent fat meal. Significant gallbladder emptying was stimulated, not only by isotonic and hypertonic dextrose, but also by hypertonic saline. The gallbladder emptied more rapidly after a liquid than after a solid meal.     

Duplex ultrasound measurement of postprandial intestinal blood flow: effect of meal composition

Duplex ultrasound was used to evaluate the effects of 350-cal, 300-ml protein, fat, carbohydrate, and mixed (Ensure-Plus) liquid meals on celiac, superior mesenteric, and femoral artery blood flow in 7 healthy volunteers. Ingestion of separate water and mannitol solutions served as controls for volume and osmolarity. Duplex parameters of peak systolic velocity, end-diastolic velocity, mean velocity, and volume flow were determined before, and serially for 90 min after, ingestion of each test meal. Maximal changes were compared with baseline values. There were no significant changes in any of the blood flow parameters derived from the celiac or femoral arteries after any test meal ingested. In contrast, maximal changes in all superior mesenteric artery parameters were increased significantly over baseline (p less than 0.05) after each of the test meals except water, with end-diastolic velocity showing proportionally the greatest increase. The study demonstrates that duplex ultrasound can provide a noninvasive means of studying the reactivity of the splanchnic arterial circulation to different stimuli and documents differing blood flow responses to variation of nutrients.     

Depressor Action of Insulin on Skeletal Muscle Vasculature: A Novel Mechanism for Postprandial Hypotension in the Elderly

Objectives. We sought to assess the role of insulin in postprandial blood pressure regulation in the elderly.Background. Insulin is both a positive inotropic and chronotropic hormone that also vasodilates skeletal muscle vasculature. Insulin may thus mediate aspects of postprandial cardiovascular homeostasis.Methods. Ten healthy elderly subjects were studied in the fasting state on three separate days. After baseline supine hemodynamic and neurohumoral measurements were taken (cardiac output and superior mesenteric artery blood flow were measured using Doppler ultrasound, and calf blood flow was measured using venous occlusion plethysmography), subjects ate on one occasion a 2.5-MJ high carbohydrate meal and on the other two occasions, an isoenergetic high fat meal. One high fat meal was accompanied by an insulin infusion reproducing the plasma insulin profile seen after a high carbohydrate meal while maintaining the glycemic profile seen after a high fat meal alone. After meal ingestion, measurements were repeated every 20 min for 2 h.Results. After the three meals, there were similar increments in cardiac output and heart rate. After the high carbohydrate meal and high fat meal with insulin, mean arterial blood pressure fell by between 8 to 10 mm Hg, but did not change after the high fat meal. After the high carbohydrate meal and the high fat meal with insulin, calf vascular resistance did not change, whereas after the high fat meal, it increased by 15.5 ± 4.4 U (mean ± SEM).Conclusions. Insulin contributes to the failure of calf vasoconstriction seen after a high carbohydrate meal. By this vasodepressor action, insulin is at least in part responsible for the fall in blood pressure after a high carbohydrate meal.     

Regulation of postprandial mesenteric blood flow in humans: evidence for a cholinergic nervous reflex.

Duplex ultrasound was used to investigate superior mesenteric artery haemodynamics in humans in order to determine the physiological importance of postprandial blood concentrations of cholecystokinin octapeptide (CCK8), gastrin 17, secretin, and glucagon and to study whether a nervous cholinergic reflex mechanism has a role in the postprandial mesenteric blood flow response. Duplex parameters of vessel diameter, mean velocity, and flow volume were determined serially in the basal state and after stimulation. Changes were compared with baseline values. Superior mesenteric artery parameters were significantly increased over baseline values after a liquid test meal, but ingestion of saline did not cause any changes. Hormones infused simultaneously at postprandial concentrations did not change mesenteric blood flow. When they were infused at pharmacological doses, however, a significant increase in flow parameters was observed. Pretreatment with atropine significantly (p less than 0.05) reduced the mesenteric blood flow response to meal stimulation (57%). These data suggest that the four hormones tested are not of quantitative importance in regulating postprandial superior mesenteric artery blood flow. A cholinergic nervous reflex, however, participates in the control of food induced mesenteric artery flow changes.     

Gastric emptying of a solid meal is accelerated by the removal of dietary fibre naturally present in food.

Exogenous fibre added to liquid meals delays gastric emptying. Its effect on solid meals is uncertain, and nothing is known of the effect on gastric emptying of fibre naturally present in food. This study therefore looked at gastric emptying of two different solid meals in eight healthy subjects and their blood glucose responses. The meals were exactly equivalent except for the total dietary fibre content (high fibre 20 g, low fibre 4 g of dietary fibre per 1000 kcal) and supplied 870 kcal (700 kcal women), 47% of which was from carbohydrates, 36% from fats, and 17% from proteins. Ultrasonography was used to measure antral diameters before the meal (basal), immediately after it (time 0), and at 30, 60, 120, 180, 240, and 300 minutes. In addition, subjects filled in a questionnaire on their feelings of hunger, epigastric fullness, and satiety before the meal and at hourly intervals after it. Basal and maximal postprandial antral sections were similar for the two meals (basal section: 283.9 (29.5) v 340.9 (44.7) mm2 for the low and the high fibre meal, NS; maximal postprandial section: 1726 (101.9) v 1593 (120.4) mm2, NS). Total gastric emptying time was significantly reduced by fibre removal (186.0 (15.6) v 231.7 (17.3) minutes after the low and the high fibre meal, p < 0.05). Blood glucose was higher after the low fibre meal, and the area under the glycaemic curve significantly greater (226 (23.1) v 160 (20.0) mmol/min/dl-1, p < 0.05). No difference was found in satiety or fullness feelings, but hunger returned more rapidly after the low fibre meal. In conclusion, fibre naturally present in food delays gastric emptying of a solid meal, reduces the glycaemic response, and delays the return of hunger.     

Effects of exercise on mesenteric blood flow in man.

Transcutaneous Doppler ultrasound was used to assess the effects of exercise on both fasting and postprandial superior mesenteric artery blood flow. After treadmill exercise (speed 5 km/h, gradient 20%, duration 15 min) in 16 subjects, superior mesenteric artery blood flow decreased by 43% immediately after the end of the exercise and by 29% at five minutes and 24% at 10 minutes postexercise. The superior mesenteric artery blood flow response to a combination of a treadmill exercise and a liquid meal in 15 volunteers was significantly smaller at five minutes from the end of the stimuli, than the response to the meal alone (15 controls) (635 +/- 51 ml/min v 846 +/- 72 ml/min) (p less than 0.025), but not different at any other time. Thus exercise reduces mesenteric blood flow in both the fasting and postprandial state in normal subjects.     

Gastric emptying,postprandial blood pressure,glycaemia and splanchnic flow in Parkinson’s disease

AIM: To determine gastric emptying, blood pressure, mesenteric artery blood flow, and blood glucose responses to oral glucose in Parkinson's disease. METHODS: Twenty-one subjects(13 M, 8 F; age 64.2 ± 1.6 years) with mild to moderate Parkinson's disease(Hoehn and Yahr score 1.4 ± 0.1, duration of known disease 6.3 ± 0.9 years) consumed a 75 g glucose drink, labelled with 20 MBq 99mTc-calcium phytate. Gastric emptying was quantified with scintigraphy, blood pressure and heart rate with an automated device, superior mesenteric artery blood flow by Doppler ultrasonography and blood glucose byglucometer for 180 min. Autonomic nerve function was evaluated with cardiovascular reflex tests and upper gastrointestinal symptoms by questionnaire. RESULTS: The mean gastric half-emptying time was 106 ± 9.1 min, gastric emptying was abnormally delayed in 3 subjects(14%). Systolic and diastolic blood pressure fell(P 0.001) and mesenteric blood flow and blood glucose(P 0.001 for both) increased, following the drink. Three subjects(14%) had definite autonomic neuropathy and 8(38%) had postprandial hypotension. There were no significant relationships between changes in blood pressure, heart rate or mesenteric artery blood flow with gastric emptying. Gastric emptying was related to the score for autonomic nerve function(R = 0.55, P 0.01). There was an inverse relationship between the blood glucose at t = 30 min(R =-0.52, P 0.05), while the blood glucose at t = 180 min was related directly(R = 0.49, P 0.05), with gastric emptying. CONCLUSION: In mild to moderate Parkinson's disease, gastric emptying is related to autonomic dysfunction and a determinant of the glycaemic response to oral glucose.     

The integrated response of the cardiovascular system to food.

To obtain information about the integrated response of the cardiovascular system to food, cardiac output and regional blood flow (superior mesenteric artery, renal artery and calf blood flow) were measured in 14 normal young healthy subjects after an overnight fast and following a standard 800-kcal meal. Results were compared with 8 subjects who remained fasted throughout the study. Cardiac output increased from a mean (SEM) fasting value of 4.8 (0.3) l/min to a peak after 30 min of 6.1 (0.5) l/min (p < 0.001). Superior mesenteric blood flow increased from a fasting value of 463 (45) to a peak of 854 (110) ml/min also after 30 min (p < 0.001). These changes were accompanied by a significant fall in both systemic vascular resistance and superior mesenteric vascular resistance (p < 0.001). Only at the 15-min postprandial measurements was there a significant relationship between the increase in cardiac output and superior mesenteric artery blood flow (r = 0.62, p = 0.02). Calf blood flow increased and vascular resistance fell postprandially (p < 0.05), but there was little change in right renal artery blood flow. There was an insignificant fall in renal vascular resistance. Heart rate increased from a resting value of 65 (3) to a peak of 77 (4) beats/min after 15 and 30 min (p < 0.001), diastolic blood pressure fell postprandially with little change in systolic blood pressure. These results suggest that in healthy young subjects the increase in gut blood flow is met by an increase in cardiac output, with little evidence of redirection from other vascular beds. The early postprandial increase in superior mesenteric blood flow may account for the increase in cardiac output, although the magnitude of the change is much greater for cardiac output than superior mesenteric artery blood flow.     

Effects of fat supplementation on glycaemic response and gastric emptying in adolescents with Type 1 diabetes

Aims To compare the glycaemic response to meals with different fat content in adolescents with Type 1 diabetes mellitus (T1DM) and to investigate associations with gastric emptying. Methods In this randomized, cross‐over study, paired results were obtained from seven adolescents with T1DM who ingested on different days two meals with the same carbohydrate and protein content, but different fat and energy content (2 and 38 g fat, 320 and 640 kcal, respectively). Paracetamol was mixed into the meals and gastric emptying was estimated by the paracetamol absorption method. All subjects were normoglycaemic and given 7 IU insulin aspart at commencement of ingestion. Postprandial blood samples were taken during 4 h. Results The areas under the curves for plasma glucose and serum paracetamol concentrations were larger after the low‐fat than after the high‐fat meal during the first 2 h (P = 0.047 and P = 0.041, respectively). The difference between meals in time‐to‐peak in glucose and paracetamol concentrations did not reach statistical significance (high‐fat vs. low‐fat meal: 210 min (120–240) vs. 120 min (50–240), P = 0.080 and 120 min (75–180) vs. 60 min (60–120), P = 0.051, respectively). Changes in glucose concentrations correlated with simultaneous changes in paracetamol concentrations (P < 0.001). Conclusions For the first time, we have shown that the initial glycaemic response is reduced after a meal with higher compared with a meal with lower fat content in adolescents with T1DM given a rapid‐acting insulin analogue preprandially. The type and dose of preprandial insulin may need adjustment to the fat content of the meal to reach postprandial normoglycaemia.     

Proximal colonic response and gastrointestinal transit after high and low fat meals

The fat component of meals has been thought to make a major contribution to the colonic response to feeding. We have combined gamma scintigraphy and radiotelemetry to noninvasively study the response of the normally inaccessible proximal colon after ingestion of either a high or low fat meal. Separate studies were performed to measure the rate of passage of the same meals through the whole gut. Gastric emptying and small bowel transit of the two meals to the colon was similar, 50% of meal marker reaching the ascending colon 4.8±0.2 and 4.5±0.3 hr after the high and low fat meals respectively (N=8, difference not significant). The low fat meal caused a consistent increase in motility index, which rose from a basal value of 1.0±0.3 to 2.6±0.7 mm Hg in the 2hr after the meal (N=8,P<0.01). Response to the high fat meal was less consistent, motility index increasing from 1.6±0.6 basally to 2.3±0.7 mm Hg postprandially (N=8,P=0.21). Despite these increases in motor activity there was no net caudal propulsion of colonic contents after either meal. The geometric center was comparable, being 3.2±0.4 and 3.7±0.4 before the high and low fat meals. This did not change significantly after either meal, being then 3.5±0.4 and 3.6±0.4 2 hr after the high and low fat meals, respectively. We conclude that in normal subjects equicaloric high and low fat meals transit the whole gut at a similar rate. Furthermore, the immediate motor response of the proximal colon has a similar nonpropulsive, mixing function after both types of meal.     

Effect of Dietary Fibre on Blood Glucose,Plasma Immunoreactive Insulin,C-peptide and GIP Responses in non Insulin Dependent (Type 2) Diabetics and Controls

ABSTRACT A high fibre and a low fibre breakfast meal were given to eight non insulin dependent diabetics (NIDD), and eight controls. Blood glucose response was monitored continuously for three hours and characterized using a straight line model. After the high fibre meal the rates of increase and decrease in blood glucose concentration were slower both in diabetics and controls than after the low fibre meal. The delay time, however, i.e. the time from meal intake to the start of glucose increase, hypothetically corresponding to gastric emptying time, was the same after both test meals. The postprandial glucose increment calculated as the area under the 0–120 min curve was lower after the high fibre meal in the NIDD, but not in the controls. The two-hour C-peptide and gastric inhibitory polypeptide values were lower for the diabetics after the high fibre breakfast. The results indicate a prolonged carbohydrate digestion and/or absorption after high fibre breakfast.     

Effects of fat on gastric emptying of and the glycemic, insulin, and incretin responses to a carbohydrate meal in type 2 diabetes

CONTEXT: Gastric emptying (GE) is a major determinant of postprandial glycemia. Because the presence of fat in the small intestine inhibits GE, ingestion of fat may attenuate the glycemic response to carbohydrate. OBJECTIVE: The objective of this study was to evaluate the effect of patterns of fat consumption on GE and glucose, insulin, glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP) concentrations after a carbohydrate meal in type 2 diabetes. DESIGN: This was a randomized, cross-over study in which GE of a radioisotopically labeled potato meal was measured on 3 d. SETTING: The study was performed at the Royal Adelaide Hospital. PATIENTS: Six males with type 2 diabetes were studied. INTERVENTION: Subjects ingested 1) 30 ml water 30 min before the mashed potato (water), 2) 30 ml olive oil 30 min before the mashed potato (oil), or 3) 30 ml water 30 min before the mashed potato meal that contained 30 ml olive oil (water and oil). MAIN OUTCOME MEASURES: GE, blood glucose, plasma insulin, GLP-1, and GIP concentrations were the main outcome measures. RESULTS: GE was much slower with oil compared with both water (P < 0.0001) and water and oil (P < 0.05) and was slower after water and oil compared with water (P < 0.01). The postprandial rise in blood glucose was markedly delayed (P = 0.03), and peak glucose occurred later (P = 0.04) with oil compared with the two other meals. The rises in insulin and GIP were attenuated (P < 0.0001), whereas the GLP-1 response was greater (P = 0.0001), after oil. CONCLUSIONS: Ingestion of fat before a carbohydrate meal markedly slows GE and attenuates the postprandial rises in glucose, insulin, and GIP, but stimulates GLP-1, in type 2 diabetes.     

Effects of lipase inhibition on gastric emptying of,and on the glycaemic,insulin and cardiovascular responses to,a high-fat/carbohydrate meal in type 2 diabetes

Aims/hypotheses We examined the effects of lipase inhibition with orlistat on (i) gastric emptying of, and (ii) the glycaemic, glucagon-like peptide-1 (GLP-1) and cardiovascular responses to, a high-fat/carbohydrate meal in type 2 diabetic patients.Methods Eight type 2 diabetic patients, who were aged 62 years (median range: 49–68 years) and managed by diet alone, consumed a meal containing 65 g powdered potato, 20 g glucose reconstituted with 200 ml water (labelled with 20 MBq ^99mTc-sulphur-colloid) and 45 g margarine. They did this on two separate occasions, with and without 120 mg orlistat, and while in the seated position with their back against a gamma camera. Venous blood samples for measurement of blood glucose, plasma insulin and GLP-1 were obtained immediately before the meal and at regular intervals afterwards. Blood pressure (systolic and diastolic) and heart rate were measured using an automated device.Results Gastric emptying of the meal was faster after orlistat than without orlistat (50% emptying time [mean ± SEM], 61±8 min vs 98±5 min; p=0.0001). In the first 60 min after the meal blood glucose (p=0.001) and plasma insulin (p=0.01) concentrations were higher in patients who had taken orlistat; between 60 and 180 min plasma GLP-1 (p=0.02) concentrations were lower after orlistat than without orlistat. Between 0 and 30 min systolic blood pressure (p=0.003) was lower, and heart rate (p=0.03) greater in subjects who had taken orlistat than in those who had not.Conclusions/interpretation Inhibition of fat digestion by orlistat may—as a result of more rapid gastric emptying—exacerbate postprandial glycaemia and the postprandial fall in blood pressure in patients with type 2 diabetes after ingestion of meals containing fat and carbohydrate.Conflict of Interest: None of the authors have a conflict of interest in relation to this study.     

Effect of ethanol upon gastric emptying.

The effect of ethanol upon gastric emptying in healthy human subjects was studied by measuring the gastric emptying rates of three 750 ml meals, the osmolalities, energy densities, and pH of which were similar. Meal A, which contained 80 ml alcohol, emptied more rapidly than meal B, which contained 40 ml ethanol and 63.3 g dextrose; and meal B emptied more rapidly than meal C, which contained 126.6 g dextrose but no ethanol. The slower rate of emptying of the dextrose meal (C) was not due to an increased gastric secretory rate, as serial measurements of gastric pH were substantially and significantly higher with this than with the other two meals; nor was it due to a greater degree of duodenogastric reflux, as serial measurements of gastric bile acid concentrations were similar for the three meals. We conclude that the duodenal osmoreceptor mechanism is relatively insensitive to ethanol; that the relationship between energy density and gastric emptying rate does not hold in the case of ethanol; and that the gastro-oesophageal reflux which occurs in response to ethanol is not due to impairment of gastric emptying.     

Effect of high protein and fat diet on postprandial blood glucose levels in children and adolescents with type 1 diabetes in Cairo,Egypt

Background and aimsTo determine the effect of high protein and high fat meals on post prandial glycemia in patients with type 1 diabetes.MethodsThis study included 51 children and adolescents with type 1 diabetes who were following up at Diabetes, Endocrine and Metabolism Pediatric Unit (DEMPU), Abo Elrish Children’s hospital, Cairo University.Post prandial blood glucose levels were recorded and compared following three breakfast meals with varying protein and fat content (standard carbohydrate meal, high fat meal, and high protein meal) over a period of 5 hours on 3 consecutive days.ResultsHigh protein meal resulted in hyperglycemia with the peak level at 3.5 hours and continued for 5 hours post prandial while high fat meal caused early hyperglycemia reached the peak at 2 hours then declined towards 5 hours.Comparison of the three different breakfast meals revealed statistically significant difference regarding the postprandial glycemia at 30, 60, 90,120, 180, 210, 240, 270, 300 min.ConclusionMeals high in protein caused sustained increase in postprandial glucose levels over a period of 5 h. However, high fat meals caused early postprandial hyperglycemia. Protein and fat content of meals affect the timing and values of the peak blood glucose as well as the duration of postprandial hyperglycemia. Therefore, fat/protein unit should be taken in consideration while calculating the bolus insulin dose and anticipating the postprandial glucose response.     

Effects of cisapride on gastric emptying of oil and aqueous meal components, hunger, and fullness.

To evaluate the effects of cisapride on gastric emptying of extracellular fat and hunger and fullness 10 volunteers consumed a meal consisting of 60 ml technectium-99m (99mTc)-V-thiocyanate labelled olive oil and 290 ml indium-113m (113mIn) labelled soup after taking cisapride (10 mg four times daily orally) and placebo, each for four days, in randomised, double blind fashion. Gastric emptying was quantified scintigraphically. Hunger and fullness before and after the meal were evaluated using visual analogue scales. Cisapride accelerated gastric emptying of oil and aqueous components by reducing the lag phase mean (SEM) (20.3 (7.0) min v 40.7 (4.1) min (p < 0.05) for oil and 4.1 (2.5) min v 10.0 (3.1) min (p < 0.05) for aqueous). Cisapride had no effect on the post-lag emptying rate of oil. Treatment with cisapride was associated with reduced retention of oil in the proximal stomach (p < 0.05). Subjects were more hungry before ingestion of the meal while receiving cisapride (6.7 (0.9) v 3.9 (0.7), p < 0.001). The scores for hunger at 120 and 180 minutes were inversely related to gastric emptying of oil on both cisapride (r > -0.62, p < 0.05) and placebo (r > -0.86, p < 0.001). Fullness increased after the meal while receiving placebo (p < 0.01), but not cisapride and postprandial fullness was less with cisapride at (30 min; 0.4 (0.3) v 3.3 (1.0), p < 0.05). With placebo, but not cisapride, the score for fullness at 15 minutes was inversely related to emptying of the aqueous phase (r = 0.68, p < 0.05). These results show that in normal volunteers after ingestion of an oil/aqueous meal: (a) postprandial hunger is inversely related to gastric emptying of oil, while fullness is inversely related to gastric emptying of the aqueous phase, (b) cisapride affects the intragastric distribution and accelerates gastric emptying of both oil and aqueous meal components, and (c) cisapride increases preprandial hunger and reduces postprandial fullness.     

Role of cholecystokinin in relaxation of the proximal stomach

Ingestion of a meal causes proximal gastric relaxation (accommodation). The magnitude of accommodation is related to the fat content of the meal. A role for cholecystokinin (CCK) has been suggested. However, under fasting conditions intravenous CCK to postprandial levels does not induce a similar accommodation. This study further explores the role of CCK in accommodation. A gastric barostat was used in eight healthy persons to study accommodation in response to a carbohydrate meal with intravenous CCK (CH-CCK), carbohydrate meal with intravenous placebo (CH-placebo) and a fat rich meal with intravenous placebo (FAT). VAS scores for satiety and plasma CCK levels were obtained. In the first postprandial hour the FAT meal induced a relaxation of 112 +/- 29 ml, the CH-CCK meal 49 +/- 36 ml and the CH-placebo meal 12 +/- 32 ml (FAT versus CH-placebo P = 0.03; FAT versus CH-CCK P = 0.09). In the second postprandial hour, intragastric bag volume returned to baseline with all meals. The FAT meal had the most pronounced effect with respect to satiety, CH-placebo the least. In the first postprandial hour, plasma CCK levels increased with the CH-CCK and FAT meals but not with the CH-placebo meal; in the second postprandial hour, levels remained elevated with the CH-CCK meal. It is concluded that a carbohydrate meal with exogenous CCK does not induce fundic relaxation, whereas a fat-rich meal (endogenous CCK) does, despite similar plasma CCK levels.