Emptying Of Fat Research Articles

Orlistat accentuates the fat-induced fall in blood pressure in older adults

Postprandial hypotension may be influenced by the digestion of fat. The aim of the present study was to evaluate the hypothesis that products of fat digestion mediate the hypotensive response to fat. In part A of the study, nine healthy older subjects were studied on three separate occasions in randomised order. Blood pressure, heart rate (HR), plasma TAG and gastric emptying were measured following the ingestion of equivolaemic drinks: (1) 300ml of high-fat drink (88% fat); (2) fat drink mixed with 120mg orlistat (lipase inhibitor); (3) water (control). In part B of the study, ten healthy older subjects were studied on two separate occasions. Blood pressure, HR, plasma TAG and superior mesenteric artery flow were measured during 90min intraduodenal infusions of 10% intralipid (2·7ml/min), with and without 120mg orlistat. Oral fat ingestion was associated with decreases in systolic and diastolic blood pressures (both P=0·0001) that were greater when orlistat was co-administered (both P<0·05), and an increase in HR (P=0·0001) that was inhibited by orlistat co-administration (P<0·03). Gastric emptying was slowed by oral fat digestion, and orlistat administration inhibited this slowing (P<0·04). Intraduodenal fat infusion was not associated with changes in blood pressure but increased HR (P<0·0001), an effect attenuated by orlistat (P<0·05). In conclusion, orlistat potentiates the hypotensive response to oral fat in older adults, possibly as a result of faster gastric emptying of fat. The results do not support a role for fat digestion in lowering blood pressure.

Free Fatty Acids Have More Potent Effects on Gastric Emptying, Gut Hormones, and Appetite Than Triacylglycerides

The effects of fat on gastric emptying (GE), gut hormones, and energy intake are dependent on digestion to free fatty acids (FFAs). In animals, small intestinal oleic acid inhibits energy intake more potently than the triacylglyceride (TG) triolein, but there is limited information about the comparative effects of FFA and TG in human beings. We compared the effects of FFA and TG on GE, gut hormone secretion, appetite, and energy intake in healthy males. Nine men (age, 23 +/- 2 y; body mass index, 22 +/- 1 kg/m(2)) were studied on 3 occasions to evaluate the effects of (1) 40 g oleic acid (FFA, 1830 kJ), (2) 40 g macadamia oil (TG, 1856 kJ; both 600-mL oil-in-water emulsions stabilized with 4% milk protein and labeled with 15 MBq (123)I), or (3) 600 mL 4% milk protein (control, 352 kJ), administered intragastrically, on GE, plasma cholecystokinin (CCK) and peptide-YY (PYY) levels, appetite perceptions, and subsequent energy intake. GE of FFA was much slower than that of TG (P < .05), with greater retention of FFA, than TG, in the proximal stomach (P < .001). Hunger was less (P < .05), and fullness was greater (P < .05), after FFA when compared with control and TG. Increases in plasma CCK and PYY levels were greater after FFA than TG or control (P < .05). Energy intake tended to be less after FFA compared with TG (control, 4754 +/- 610 kJ; TG, 5463 +/- 662 kJ; FFA, 4199 +/- 410 kJ). FFAs empty from the stomach more slowly, but stimulate CCK and PYY and suppress appetite more potently than TG in healthy human beings.

Intragastric Oil‐in‐Water Emulsion Fat Fraction Measured Using Inversion Recovery Echo‐Planar Magnetic Resonance Imaging

ABSTRACT: The fat fraction of an oil‐in‐water emulsion was measured in vitro and in vivo in the gastric lumen using inversion recovery echo‐planar magnetic resonance imaging and a non‐exchanging, 2‐compartment longitudinal relaxation model. This predicted the oil emulsion fat fraction in vitro well (Pearson's R= 0.97). Intragastric measurements in vivo correlated well with nasogastric aspirates taken from the stomachs of 7 healthy human subjects (R= 0.72). This method has potentially important applications in studying the properties of oil‐in‐water emulsions and also in assessing the intragastric distribution of fat emulsions in vivo and in correlating physiologic gastric emptying of fat and lipid blood absorption profiles.

Gastric Emptying in Rats following Administration of a Range of Different Fats Measured as Acetaminophen Concentration in Plasma

Aim: To investigate the gastric emptying upon administration of ten different fats in order to determine whether major differences in fatty acid profiles resulted in differences in gastric emptying. Methods: Gastric emptying was measured as the appearance of acetaminophen in plasma which represents an indirect measure of gastric emptying. Emulsified fats with added acetaminophen were fed by gavage to rats, and the plasma concentration of acetaminophen was followed for 3 h by repeated blood sampling from the carotid artery. The fats administered included rapeseed, corn, and fish oils, lard, and cocoa butter as well as different structured lipids containing decanoic acid (10:0) and long-chain n-3 polyunsaturated fatty acids of marine origin. Overall, these fats had wide variations in fatty acid compositions and triacylglycerol structures. Results: No statistically significant differences were observed in gastric emptying between the groups fed the different fats, except for the emptying of tridecanoin (tri-10:0) that was statistically significantly slower than that of randomized oil, cocoa butter, and rapeseed oil (p < 0.05). The slower emptying of tri-10:0 could be caused by a lower caloric intake of this fat as compared with the other fats, because similar weights of fat were administered. Conclusion: The gastric emptying of fat was not influenced by fatty acid composition and triacylglycerol structure of the fats administered.

Role of lipase in the regulation of postprandial gastric acid secretion and emptying of fat in humans: a study with orlistat, a highly specific lipase inhibitor

BACKGROUND AND AIMSTo investigate the importance of lipase on gastric functions, we studied the effects of orlistat, a potent and specific inhibitor of lipase, on postprandial gastric acidity and gastric...

Gastric emptying of ingested fat emulsion in rats: implications for studies of fat-induced satiety.

Evidence that ingested fat acts in the intestine to produce satiety stems from studies showing that intraintestinal infusion of fat emulsion inhibits eating behavior of rats. In this study, we determined the appropriateness of infusion parameters used in these behavioral studies by measuring gastric emptying rates of both the aqueous and lipid components of Intralipid ingested normally by rats. Stomach contents were collected at different times 0-40 min after rats ingested Intralipid containing [14C]polyethylene glycol (PEG) and phenol red (PR) and were assayed for PEG, PR, and fat. The proportion of ingested fat remaining in the stomach was significantly greater than the proportion of ingested PEG or PR at all time points examined. Despite initial gastric emptying of fat during ingestion, consumption of Intralipid (0.5 or 1.1 kcal/ml) did not suppress subsequent solid food intake. The results indicate that 1) ingested fat emulsion rapidly partitions in the rat stomach into an aqueous phase, which empties rapidly, and a lipid phase, which empties slowly, and 2) normal ingestion of Intralipid is not immediately satiating. These observations raise questions about the physiological significance of the rapid and marked suppression of feeding behavior produced by intraintestinal infusion of Intralipid.

Digestibility, blood levels of nutrients and skin responses of calves fed soyabean and lupin proteins

Three milk substitute diets in which the protein was provided either by skim milk only (control diet) or mainly (71%) by a commercial soyabean or lupin concentrate (soyabean or lupin diet, respectively) were given to intact or ileo-caecal-cannulated preruminant calves. In vitro tests showed that both concentrates were partially proteolysed and had low antigenic and antitryptic activities. The low antigenicity was confirmed in vivo since none of the calves produced specific plasma antibodies against dietary proteins, and skin reactions following the injection of these proteins were minor. Postprandial plasma level of triglycerides was higher with the 2 legume diets, suggesting faster abomasal emptying of fat and probably protein. Apparent faecal nitrogen digestibility was lower (P < or = 0.05) with the soyabean and lupin diets than with the control diet (0.86, 0.88 and 0.95, respectively). At the ileal level, the differences were smaller and non-significant (0.90, 0.88 and 0.92) for nitrogen, but remained significant for valine and tyrosine with the soyabean diet, and for proline, valine, methionine, leucine and lysine with the lupin diet. However, the differences were small enough to conclude that proper denaturation of soyabean and lupin proteins by processes including partial hydrolysis can suppress their antigenicity and render them very digestible.

Factors that affect the performance of lipase on fat digestion and absorption in a canine model of pancreatic insufficiency.

In a previous experiment, absorption of [14C]triolein was poor under low lipase in the first postcibal hour during which luminal conditions change markedly. We wondered how low lipase might be affected by changing concentrations of fat, bile salts, titratable acid, pepsin, and food particles. Therefore, in dogs with duodenal and midintestinal fistulas, endogenous bile and pancreatic juice were excluded from the intestinal lumen and replaced with varied amounts of exogenous bile and pancreatic enzymes during steady perfusions. Oil emulsions contained [14C]triolein and [3H]glycerotriether. A double isotope ratio method and a double isotope, double extraction method were used to determine, respectively, the amount of [14C]triolein absorbed and hydrolyzed by the midgut. Lipolysis increased with both substrate and enzyme inflows, whether inflows were varied by changing concentrations or rates of volume flow. But at increasing rates of fat entry, the percent of fat hydrolyzed by the midgut declined. Neither pH 4 nor 5 citrate affected fat hydrolysis or absorption when titratable acid was infused at rates < or = 16 mEq/h; but pepsin reduced both. Whereas meat particles bound lipase, their presence augmented lipolysis. We speculate that rapid gastric emptying of fat and peptic deactivation of duodenal lipase were the main factors responsible for the previously poor performance of low lipase in the first postcibal hour.

Control of canine gastric emptying of fat by lipolytic products.

Dietary fat is ingested in three forms: 1) in solid food, 2) as aqueous emulsions, and 3) as unemulsified, liquid oil. On the basis of a scant previous literature, we postulated that liquid fat (emulsions or oils) would empty from the stomach at speeds that varied with the amounts ingested but that this dynamic would be modulated by feedback inhibition from lipolytic products. To test these ideas, we used a gamma camera to track gastric emptying of 123I-labeled fat in dogs with chronic pancreatic fistulas by which lipase was excluded from or replenished in the duodenum in varied amounts after dogs were fed 15-, 30-, and 60-g loads of liquid fat given with solid foods or as emulsions. We also tracked concurrent gastric emptying of 113mIn, which marked the solid food phase or the water phase of emulsions. In some studies, we used a potent and specific inhibitor (orlistat) of pancreatic and gastric lipases to assess how lipolytic products modulated emptying of liquid fat. In the absence of pancreatic enzymes, both oils and emulsions emptied initially at high speeds that varied with fat loads, but emptying slowed 20 min after ingestion of emulsions and 60 min after ingestion of unemulsified oil. Studies with orlistat indicated that these changes in rates resulted from liberation of gastric lipolytic products. Emptying of oil emulsions was not altered by duodenal replenishment with pancreatic enzymes, but emptying of unemulsified oil was inhibited in a dose-related fashion, such that maximal inhibition was achieved when pancreatic enzymes were replenished at > or = 40% of normal amounts. Studies with orlistat confirmed that this dose-dependent slowing was due specifically to lipase. Emptying of solid food was much more sensitive to replenishment with enzymes, so that a 10% replenishment maximally inhibited solid emptying.

The effect of posture on gastric emptying and intragastric distribution of oil and aqueous meal components and appetite

Background: It is uncertain whether gastric emptying of fat is determined mainly by its physical characteristics or chemical composition. In particular, the intragastric distribution of extracellular fat and the importance of that distribution to gastric emptying of fat is controversial. The effects of posture on gastric emptying, intragastric distribution, and appetite after ingestion of a meal containing oil and aqueous phases was evaluated. Methods: Eleven volunteers consumed 60 ml 99mTc-(V)-thiocyanate-labeled olive oil and 290 mL 113mIn-labeled soup while sitting and while lying in the left lateral decubitus position. Hunger before and after the meal was recorded. Results: In the sitting position, oil emptied from the stomach more slowly (P < 0.01) whereas in the decubitus position oil emptied faster (P < 0.01) than the aqueous phase. Oil was preferentially retained in the proximal stomach when sitting (P < 0.01), and more oil was retained in the distal stomach in the decubitus position (P < 0.05). The amount of oil that emptied in the first 180 minutes was not different between the two postures. The aqueous phase emptied much more slowly (P < 0.01) in the decubitus position. At 120 minutes and 180 minutes, subjects were less hungry (P < 0.05) in the decubitus position. In the decubitus position, hunger at 120 minutes and 180 minutes was related to the retention of oil (r ≥ 0.79; P < 0.01) in the stomach. Conclusions: These results indicate that (1) gravity has a major effect on the intragastric distribution and relatively little effect on total stomach emptying of oil, and (2) postprandial hunger is affected by posture and, in the decubitus position, is inversely related to the amount of oil that has entered the small intestine.

GIP and insulin release in relation to gastric emptying of a mixed meal in man

To clarify the role of GIP (gastric inhibitory polypeptide) as an incretin, we related temporally the gastric emptying of fat, protein and glucose to plasma levels of glucose, GIP and insulin in man. Five healthy volunteers with a multiple lumen duodenal tube ingested a mixed meal with phase-specific markers for the the aqueous phase, liquid fat and the solid protein phase. Duodenal passage was determined by intraduodenal infusion of a second set of phase-specific non-absorbable markers. Plasma insulin rose rapidly from a basal value of 59 pM to 300 pM at 60 min, and then declined to reach basal levels after 180 min. By contrast, plasma GIP rose more slowly than insulin, from a basal value of 9.4 pM, and remained elevated, in the range of 14–18 pM, throughout the 240 min observation period. The time course of plasma insulin concentration paralleled gastric emptying of the aqueous phase, containing most of the meal's glucose ( r = 0.952, P < 0.001). The time course of plasma GIP concentrations paralleled the gastric emptying of fat and protein ( r = 0.763−0.834; P < 0.01−0.05). Plasma insulin concentrations showed no correlation to the rate of emptying of fat and protein ( r = 0.142−0.420; n.s.) and to plasma levels of GIP ( r = 0.365; n.s.). The threshold for plasma glucose at which GIP would exert an incretin effect was only reached at one time point, 30 min after ingestion of the meal. Our findings of simultaneously tracked gastric emptying of meal nutrients, hormone release and plasma glucose levels do not support an important physiological role for GIP as an insulinotropic hormone after ingestion of mixed meals in man.

Digestion des protéines de pois et de soja chez le veau préruminant. I. Taux circulants de nutriments, formation d'anticorps et perméabilité intestinale aux macromolécules

Three milk-substitutes (control, pea and soya-bean)were given to 6 preruminant calves. In the control diet protein was almost entirely provided by skim milk powder. In the pea diet a pregelatinized dehulled pea flour provided 33.5% of the protein, the remainder being supplied by skim milk powder. In the soya-bean diet, 73.2% of the protein were provided by a soya-bean isolate and the remainder by whey powder. The concentrations of plasma triglycerides and the free alpha-amino nitrogen in the peripheral blood were lower with the pea and soya-bean diets than with the control diet before the morning meal, but became higher after feeding. That suggested a faster abomasal emptying of fat and protein with the pea and especially the soya-bean diet. Systemic antibody responses were induced against pea protein but not against soya-bean protein. No effect of the diet on the plasma concentration of immunoreactive beta-lactoglobulin was apparent after 6 days, suggesting there was no important change in gut permeability at least at that time.

Temporal relationships of cholecystokinin release, pancreatobiliary secretion, and gastric emptying of a mixed meal

The influence of gastric emptying of nutrients on plasma cholecystokinin and pancreatobiliary functions is poorly understood. We therefore temporally related the emptying of fat, protein, and glucose of a mixed meal to release of the gut hormones cholecystokinin, pancreatic polypeptide, and peptide YY and outputs of trypsin, lipase, bilirubin, and bile salts. Five healthy volunteers with a multilumen duodenal tube ingested a mixed meal with phasespecific markers for the aqueous phase, liquid fat, solid fat, and solid protein phases. Duodenal passage was determined by intraduodenal infusion of a second set of phase-specific nonabsorbable markers. Plasma cholecystokinin levels and pancreatobiliary secretions rose to a maximum at 30–60 min and then gradually declined (p < 0.01) despite continued entry of protein and fat into the duodenum throughout the whole 4-h experimental period. High levels of both pancreatic polypeptide and peptide YY were observed in the last 2 h of the experiment. Release of factors capable of inhibiting cholecystokinin release and subsequently pancreatobiliary secretion may be responsible for the observed time-course.

Influence of enkephalinase inhibitors on gastric emptying in mice depends on the nature of the meal

The effects of two enkephalinase inhibitors (thiorphan and acétorphan) and DALAMIDE on gastric emptying of fat or non-fat meals were evaluated in mice. When administered intraperitonally at low doses (0.1 and 0.2 mg/kg) 30 min prior to a fatty (milk) meal, both thiorphan and acetorphan increased significantly (P < 0.01) gastric emptying; these effects were maximal for 0.2 and 0.1 mg/kg respectively and decreased progressively to be not significant for doses higher than 5 mg/kg for thiorphan and 0.5 mg/kg for acetorphan. Similarly DALAMIDE given IP increased significantly (P < 0.05) gastric emptying at doses of 0.5 and 1 mg/kg while a slowing of gastric emptying was obtained for 10 times higher doses. The effects of thiorphan (0.2 mg/kg) and DALAMIDE (0.5 mg/kg) were blocked by previous administration of naloxone (0.3 mg/kg) and methyl-naloxone (0.5 mg/kg) while only naloxone (0.3 mg/kg) blocked the slowing effect of high dose of DALAMIDE. Administered prior to a non-fat meal, thiorphan (1 mg/kg) stimulated gastric emptying and inhibited it at higher dosage (10 mg/kg). Neither acetorphan nor DALAMIDE at similar dosages affected the gastric emptying of a non-fat meal and the effects of thiorphan (1 and 0.1 mg/kg) were not blocked by naloxone (0.3 mg/kg). It is concluded that enkephalinase inhibitors (thiorphan and acetorphan) administered systematically stimulate the gastric emptying of a fat meal by increasing enkephalin levels in peripheral tissues, while thiorphan exhibits non-opiate effects on gastric emptying of a non-fat meal.

Gastric processing and emptying of fat

This study was undertaken to determine whether fat leaves the stomach within or bound to the surface of particles of solid food. We studied gastric emptying of fat in 6 human subjects and in 6 dogs with Roux-en-Y duodenojejunostomies so that chyme leaving the stomach could be collected free of bile and pancreatic enzymes. Humans were studied with a duodenal multilumen tube so that phase-specific, nonabsorbed markers in the meal could be tracked with corresponding, phase-specific markers perfused into the duodenum. In this way, we observed the separate time-courses of gastric emptying of the aqueous and solid phases, as well as the extracellular fat (ECF) and intracellular fat (ICF) phases of the meal. In the dogs, all chyme leaving the stomach was collected from a Roux-en-Y fistula and was analyzed directly for aqueous, solid, ECF, and ICF markers in the meal. In both the humans and the dogs, the aqueous phase emptied promptly, whereas the solid, ECF, and ICF phases emptied together, in parallel, after an initial lag. In humans, 22% of the ECF versus 51% of the ICF (p < 0.02) emptied on or in the solid food particles. In dogs, 81% of the ECF emptied as an oil, 13% emptied on the solid particles, and only 6% emptied as a stable, aqueous emulsion. Sixty-six percent of the ICF emptied in the solid food particles, 20% as a stable, aqueous emulsion, and 14% as an oil. We conclude that most of the ICF empties within the solid food phase, whereas most of the ECF empties as an oil phase.

Gastric emptying and intragastric distribution of lipids in man. A new scintigraphic method of study.

We measured gastric emptying of fat and water from a solid-liquid meal in healthy volunteers using a tubeless scintigraphic method. Selenium-75 glycerol triether, incorporated in butter, was the lipid-phase marker, and technetium-99m, ingested with 250 ml water, the non-lipid phase marker. In seven of these subjects we also measured the gastric emptying of solids and liquids with technetium-99m bound to cooked egg whites as the solid-phase marker and indium-111 ingested with 250 ml water as the marker of the solid and aqueous phases. Emptying and intragastric repartition of each marker were measured by detection of radioactivity changes over the abdominal area using a gamma-camera. The stability and the specificity of the labeling was checked for each marker. Mean gastric emptying rate (expressed as percentage ingested marker emptied per hr) of lipids (17.4 +/- 2.4) was much lower than that of the rest of the meal (34.2 +/- 1.8) and slightly, but significantly, lower than that of solids (22.8 +/- 1.8). An intragastric layering of fat above nonlipids was observed only after the first postprandial hour and remained moderate. Thus, lipids are emptied more slowly than any other component of an ordinary meal, and this is not due only to layering of fat above water.

Gastric Emptying of Glucose and Nutrient Energy in Meal-Fed Rats

Male rats (designated “meal-feeders”) were trained for at least 21 days to eat voraciously for 2 hours a day a high-glucose, nutritionally adequate diet, while “nibblers” were fed the same diet ad libitum. In experiment 1, a second control group received the same amount of diet as eaten by meal-feeders but in four meals per day. Final test meals comprised either 10 g per (kilogram body weight)¾ or all that the animal would eat in a 2-hour period. With both sizes of test meal, gastric emptying of fat and/or glucose was greater in meal-feeders than in either control group. In experiment 2, gastric emptying of glucose and fat was measured in meal-feeders and nibblers during three intervals of the dark period and during the 12-hour light period. An unusually rapid gastric emptying of glucose and of metabolic energy was observed in meal-feeders but was confined to the early period after the start of the daily meal. Glucose was emptied preferentially to fat under all test conditions. This tendency was prominent, however, only when a small meal was fed or after stomach contents had declined.gastric emptying meal-feeding nibbling pattern diurnal rhythms

Parallel Gastric Emptying of Nonhydrolyzable Fat and Water After a Solid-Liquid Meal in Humans

Our aim was to examine the control of gastric emptying of the oil phase of a mixed solid and liquid meal. Previous studies had shown that liquid dietary fats normally leave the stomach at a slower rate than does water. We wished to determine whether the slower emptying of fats was due to the physical characteristics of food (lower density and greater viscosity than water), to retardation by duodenal feedback mechanisms, or whether both factors contributed. Thus, we quantified the emptying rates of water and sucrose polyester (a nonabsorbable analog of dietary fat) ingested by healthy volunteers as a mixed solid and liquid meal. Gastric emptying was quantified by an intubation-perfusion method incorporating an occlusive jejunal balloon to facilitate recovery. Four phase-specific, nonabsorbable markers were used. [14C[Sucrose octaoleate and polyethylene glycol were incorporated in the meal and traced the lipid and water phases, respectively; [3H]glycerol triether and phenolsulfonphthalein were used as duodenal recovery markers. Sucrose polyester (substituting for dietary fat) was emptied very rapidly, and at about the same rate as was water, in contrast to natural fat, which empties very slowly. Emptying of water was rapid and comparable to that observed after mixed meals containing natural fat. These results imply that gastric emptying of the oil phase is controlled by receptors sensitive to the hydrolytic products of fat digestion and that the slow emptying of dietary fat is not simply due to its lower density.

Gastric emptying of lipids after ingestion of a solid-liquid meal in humans

We measured gastric emptying of fat and water from a mixed meal in 6 healthy volunteers using a technique of duodenal perfusion that included phase-specific, nonabsorbable markers. Pairs of water-soluble markers (polyethylene glycol 4000 and phenolsulfonphthalein) and (equivalent) lipid-soluble ([14C]sucrose octaoleate and [3H]glycerol triether) markers were used. For each pair, one marker was used to label the corresponding component of the meal (water or fat), and the other was perfused into the duodenum as a recovery marker. The perfusion method was validated by comparing the amount of marker emptied, as estimated by marker dilution, with the amount obtained by complete aspiration of intestinal contents proximal to an occlusive balloon. Throughout the postprandial period, ratios of lipid marker to total fatty acids in the stomach remained constant, indicating a stable relationship of meal marker to total lipids. Water always emptied faster than did lipids, substantial amounts of which were still in the stomach after 6 h. There was close agreement between recovery of fat proximal to the balloon and calculations of lipid emptying from duodenal perfusion, supporting the validity of the marker dilution technique for the gastric emptying of lipids. This study demonstrates that when ingested as part of an ordinary mixed meal, water and fat have different patterns of emptying, water leaving the stomach first.

Gastric emptying following Finney pyloroplasty and vagotomy.

Gastric emptying was evaluated in a series of unanesthetized dogs in the intact state, following Finney pyloroplasty, and with the addition of vagotomy. Sodium chromate labeled test meals of glucose, trisodium citrate, and trisodium citrate-fat were used. Finney pyloroplasty resulted in a trend for delayed emptying of fat from the stomach. The trisodium citrate test meal increased the levels of gastric secretion after pyloroplasty.