Lymphatic transport in rats of interesterified oils containing conjugated linoleic acids

In this study we examined the lymphatic transport in rats of FA after administration of interesterified oils containing CLA, with emphasis on the location of CLA and octanoic acid in the TAG. The oils were produced by enzymatic interesterification. Eight oils with different structures or FA profiles were examined in this study: MCM, CMC, OCO, and COC, where M was expected to be octanoic acid and O oleic acid. In group 1, C was CLA as a mixture of the two CLA isomers c9, t11 or t10, c12, and in group 2, C was mainly the isomer t10, c12. Rats were subjected to cannulation of the mesenteric lymph duct, and the following day they were intragastrically administered one of the oils and lymph samples were collected for 24 h. The lymphatic transport of total FA from 0 to 8 h in group 1 was significantly (P < 0.05) higher for the OCO-1 and the COC-1 oils than for the CMC-1 oil. Similarly, in group 2 the transport was higher for the OCO-2 oil than for the CMC-2 oil. The recovery of both of the CLA isomers examined was similar (50-70%) and independent of the isomer, oil structure, and FA profile, whereas more octanoic acid was recovered from the CMC oils than from the MCM oils. The results indicated that the FA profiles and the position of octanoic acid had only a minor influence on the absorption of CLA.     

Size and number of lymph particles measured by a particle sizer during absorption of structured oils in rats

Chylomicrons transport absorbed fat from the intestine to the circulation. During dietary fat absorption, the chylomicrons become larger in diameter, and in some studies an increase in chylomicron number has been observed as well. In the present study, we compared particle size and number in rat lymph following administration of four different oils. We administered fish oil, medium-chain TAG (MCT), and two structured oils differing in intramolecular structure, with either medium-chain FA in the outer positions of the TAG and long-chain n−3 PUFA in the sn-2 position (MLM oil) or with the reverse structure (LML oil), to lymph-cannulated rats and collected lymph in fractions for the following 8 h. Chylomicron size was measured by a particle size analyzer immediately after collection, and from these data the number of chylomicrons present was estimated. The number of particles in lymph increased during the absorption of oils containing long-chain PUFA (MLM, LML, and fish oil), whereas it was not affected by administration of MCT. The FA from MCT were probably absorbed via the portal vein; therefore, only a small number of particles were measured in lymph. When comparing the two structured oils, we observed a tendency toward a higher number of particles after LML administration, although the difference was not statistically significant. The highest number of particles after administration of all oils was observed in the size intervals 53–80 and 80–121 nm and probably represented small chylomicrons. Thus, the FA composition influenced the number of particles in lymph during absorption, whereas TAG structure had only a minor influence.     

Absorption of triglycerides with defined or random structure by rats with biliary and pancreatic diversion

Fat absorption may be compromised by pancreatic or bile insufficiency, resulting in low uptake of essential fatty acid and energy. Using a rat model of malabsorption, we examined the absorption of defined triglycerides with medium-chain fatty acids (MCFA) in thesn-1,3 positions and essential fatty acids in thesn-2 position (MLM) compared to other fats. The thoracic duct was cannulated for collection of lymph, and the common bile and pancreatic duct was cannulated to divert both the pancreatic juice and bile. The rats were given a single bolus of triglyceride as a taurocholate emulsion. Fat absorption was measured from collected lymph samples. The triglycerides administered were a defined triglyceride, MLM [mainly (8∶0/10∶0)-(18∶2n−6)-(8∶0/10∶0)], a similar triglyceride subjected to chemical randomization, a mixture of medium-chain triglycerides and soybean oil, and soybean oil, respectively. The first three triglycerides had approximately 36 wt% linoleic acid (18∶2n−6) content. Administration of defined triglyceride was followed by significantly higher lymphatic level (wt%) of 18∶2n−6 (P<0.01) as well as a relative enhancement in mol% of 18∶2n−6 (P<0.05) compared to the other triglycerides. Lymphatic absorption of MCFA was similar in the three first groups but not as efficient as for long-chain fatty acids. Our results indicate that defined triglycerides thus may provide a means to increase absorption of essential fatty acids in fat malabsorption, such as that seen in cystic fibrosis, or for pre-term infants. Honored Student presentation, 84th AOCS Annual Meeting & Expo, Anaheim, California.     

Absorption in rats of rapeseed, soybean, and sunflower oils before and following moderate heating

Rapeseed, soybean, and sunflower oil were heated for 15 min in a 5-mm oil layer in a pan at 180°C. The fatty acid composition was almost unaffected by heating, while the polymer content rose slightly and the tocopherol content decreased, except in soybean oil. The absorption of oils before and after heating was investigated in lymph-cannulated rats. Oils were administered as emulsions through a gastrostomy tube and lymph was collected during the next 24 h. The highest accumulated lymphatic transport of total fatty acids was observed after administration of rapeseed oil, and the lowest after heated sunflower oil. The accumulated transport was similar for all unheated oils. The transport of fatty acids was significantly lower in rats receiving heated oil compared to those receiving the corresponding unheated oil. Small increases in polymers may have contributed to the decreased lymphatic transport of oil following heating, although this probably does not fully explain the effect. The absorption of sunflower oil was more affected by heating than the absorption of soybean or rapeseed oil. Furthermore, the largest decrease in total activity of tocopherols following heating was observed in sunflower oil. Overall, these results demonstrate that the absorption of vegetable oils is affected by moderate heating.     

Lymphatic fatty acid absorption profile during 24 hours after administration of triglycerides to rats

In this study we determined in rats the complete 24-h lymphatic fatty acid profile after administration of either rapeseed oil (RO) or rapeseed oil interesterified with 10∶0 (RO/C₁₀) with special emphasis on the transition from absorptive to postabsorptive phase. Rats were subjected to cannulation of the main mesenteric lymph duct and the next day oils were administered through a gastric feeding tube. Lymph was collected in 1-h fractions for the following 24 h. The time for maximum lymphatic transport of fatty acids was at 4 h with fast changes in fatty acid composition from the fatty acids of endogenous origin to those of the administered oils. Seven to eight hours after administration the transport was significantly lower than maximum, indicating the change from absorptive to postabsorptive phase. At 24 h after administration of either oil the transport of total fatty acids, palmitic acid (16∶0), and linoleic acid (18∶2n−6) together with oleic acid (18∶1n−9) after RO had not returned to the transport at baseline. In contrast, the transport of decanoic acid (10∶0) and α-linolenic acid (18∶3n−3) returned to baseline values between 12 and 15 h. This indicated that the absorption of purely exogenous fatty acids (illustrated by 10∶0 and 18∶3n−3) was complete at 15 h and that the fatty acids transported between 15 and 24 h were derived mostly from endogenous stores.     

Lymphatic transport of a physical mixture of medium-and long-chain TAG in rats

Lymphatic transport of a mixture of medium-chain TAG (MCT) and long-chain TAG (LCT) was studied in lymph-cannulated rats. Animals were administered a test emulsion containing either triolein, tricaprylin, or a 1∶1 mixture of triolein and tricaprylin, and the lymph was collected for 24 h. The lymphatic recovery rate of medium-chain FA (MCFA) was significantly higher in rats given the TAG mixture than in those given MCT alone. The lymphatic recovery rate of long-chain FA (LCFA) also was significantly higher in rats given the TAG mixture than in those given LCT alone. No TAG containing three MCFA (i.e., MCT) was detected, and 37.7% of TAG containing one or two MCFA was detected in the lymph TAG when rats were given the TAG mixture. These results indicate that lymphatic transport of MCFA and LCFA can be modified by the combination of MCT and LCT.     

Obligatory role of bile for the intestinal absorption of vitamin E

Normal, white female rats subjected to cannulation of the abdominal thoracic duct have been utilized for a study on the essentiality of biliary and pancreatic secretions for the intestinal absorption of vitamin E. In all animals the thoracic duct lymph was collected. Some rats had the enterohepatic circulation undisturbed and in others bile or pancreatic juice or both were drained to the exterior by appropriate catheters in the common bile duct. On the first postoperative day, the animals received intragastrically an emulsion containing protein, carbohydrate, monoolein, 2 mg ofd,l-α-tocopheryl acetate plus 50 μC ofd,l-α-tocopheryl-1’,2’-³H-acetate. The appearance of radioactive α-tocopherol and its derivatives was determined in lymph, hourly, after emulsion administration. The obligatory role of bile in intestinal absorption ofd,l-α-tocopheryl-1’,2’-³H-acetate has been established. Pancreatic juice seems to be necessary for the hydrolysis of the vitamin E acetate ester. The simultaneous infusion of bile and pancreatic juice promotes absorption of about 10% of the administered dose into the lymph. A chromatographic separation of the radioactive vitamin E fractions revealed that most of the vitamin E, which is actively transfered from the intestinal lumen to the lymph, is nonesterified. An oxidation product of α-tocopherol, presumably itsp-quinone, appears in small amounts in the lymph, but almost no labeled α-tocopheryl acetate could be detected under these experimental conditions.     

Role of the lymphatic system in the transport of absorbed 7,12-dimethylbenzanthracene in the rat

To determine the role of the intestinal lymphatic system in the absorption of a polycyclic aromatic hydrocarbon, 7,12-dimethylbenzanthracene, a radiolabeled preparation of the compound was given by intraduodenal infusion to rats in doses of 10 μg, 10 mg and 20 mg in olive oil solution. The hydrocarbon appeared to be absorbed from the intestine in a fractional manner, ca. 20% of the administered radioactivity being recovered totally in bile and intestinal lymph in 24 hr at all three dose levels. Biliary radiolabel accounted for 75–82% of combined recovery of radioactivity in bile and lymph with all three doses. The recovery of significant amounts of radiolabel in bile before the appearance of isotope in lymph, together with the fact that the biliary radiolabel greatly exceeded at all times the lymphatic recovery of isotope, suggests that an alternative pathway, presumably the portal venous route, is of major importance in the transport of the absorbed hydrocarbon.     

A comparative in vivo study of intestinal absorption of biliary phosphatidylcholines and micellar phosphatidylcholines in the rat

An in vivo study was performed using rats with the purpose of comparing the absorption of native biliary and purified phosphatidylcholines. The latter were purified from bile and solubilized in the form of mixed micelles of bile saltsphosphatidylcholines-cholesterol. The animals all bore bile duct diversions, and were divided into two groups: one had a normal pancreatic secretion while in the other group the pancreatic duct was ligated. Animals with normal pancreatic secretion showed comparable rates of absorption of micellar and biliary phosphatidylcholines. In the absence of normal pancreatic secretion, the rate of absorption of biliary phosphatidylcholines was unchanged, whereas that of micellar phosphatidylcholines markedly decreased. The results are consistent with the concept that some billary phosphatidylcholines are absorbed independently of pancreatic secretion in an unhydrolyzed form.     

Comparison of the lymphatic transport of radiolabeled 1,3-dioleoylglycerol and trioleoylglycerol in rats

It has been reported that, compared with TAG, DAG suppresses postprandial hypertriacylglycerolemia and reduces visceral fat levels in experimental animals and humans. To clarify the mechanism responsible for these beneficial effects, we compared the lymphatic transport of 1,3-DAG, a major isomer of DAG, and TAG in rats. Male SD rats, after insertion of a cannula into the thoracic duct, were given 1,3-di[1-¹⁴C]oleoylglycerol or tri[1-¹⁴C]oleoylglycerol via a stomach tube. The 24-h receovery of the radioactivity from 1,3-di[¹⁴C]oleoylglycerol in the lymph was slightly but significantly lower than that from tri[¹⁴C]oleoylglycerol (81.3±1.0 vs. 86.5±1.2%, respectively). However, in the first 1-h interval after administration, the recovery of radioactivity from 1,3-dioleoylglycerol was almost half of that from trioleoylglycerol (17.5±2.0 vs. 31.1±1.4%). The amount of TAG and phospholipids secreted into the lymph was significantly lower 1 h after the administration of 1,3-dioleoylglycerol compared with that after the administration of trioleoylglycerol. More than 90% of the radioactivity recovered in the lymph in the first 3 h was distributed in the TAG fraction for both 1,3-dioleoylglycerol and trioleoylglycerol. These results suggest that slower lymphatic transport of 1,3-DAG compared with TAG could be a factor in the suppression of postprandial hypertriacylglycerolemia. The possibility that the slower lymphatic transport of DAG contributes to the antiobesity action observed in the feeding of 1,3-DAG cannot be excluded.     

Dietary lysophospholipids reduce lymphatic cholesterol transport compared with dietary phospholipids in thoracic lymph-duct cannulated rats

Dietary phospholipids have been traditionally known to affect micelle formation. Egg yolk-derived lysophospholipids (LysoPL) are commercially available. We investigated the effects of dietary LysoPL on lymphatic lipid transport. We also compared sn-1 LysoPL and sn-2 LysoPL, which have different fatty acyl esterification positions. Thoracic lymph duct-cannulated rats were fed a diet supplemented with egg yolk-derived sn-1 LysoPL, sn-2 LysoPL, or phospholipids (PL). The amount of lymphatic lipid transport was also evaluated. Time courses of transport were applied to the one-compartment model as one of the pharmacokinetic analyses. The solubility of cholesterol in bile acid micelles was measured. Compared to the PL diet, the sn-1 and sn-2 LysoPL diets significantly reduced the lymphatic transport of cholesterol. There were no differences in the lymphatic PL and TAG transport. There was no difference in cholesterol transport between the sn-1 LysoPL group and the sn-2 LysoPL group; however, the transport rate constant at a decrease in lymphatic cholesterol was lower in the sn-1 LysoPL group than in the sn-2 LysoPL group. Cholesterol solubility in bile acid micelles was significantly decreased in the sn-1 LysoPL and sn-2 LysoPL groups compared to that in the PL group. Dietary LysoPL affects the behavior of intestinal cholesterol and suppresses lymphatic cholesterol transport.     

The role of gastric lipolysis on fat absorption and bile acid metabolism in the rat

In vivo studies were carried out in young Sprague-Dawley rats to examine the role of gastric lipolysis on fat absorption and bile acid metabolism. When fed by gastric perfusion 5 times (corn oil, 4 g/day) their usual dietary intake of fat, rats deprived of lingual lipase by the creation of an esophageal fistula had a significant degree of fat and bile acid malabsorption as well as a shortened bile acid halflife when compared to animals with a gastrostomy. The % fat absorption, bile acid loss and bile acid pool were normal in 2 groups of esophageal fistula rats fed the same quantity of corn oil or twice (8 g/day) that amount as a fine emulsion. In view of a negligible gastric lipase activity in animals with an esophageal fistula and of decreased hydrolysis of a triglyceride test meal, these data suggest that gastric lipolysis is of physiological importance in situations where lipolytic mechanisms are stressed by a large fat intake. Its principal role is to potentiate intestinal lipolysis by facilitating the emulsification of dietary lipids through its formed products and, therefore, the contact of pancreatic lipase with its substrates.     

Studies on tocopherol derivatives: V. Intestinal absorption of several d,1-3,4-3H2-α-tocopheryl esters in the rat

Twelve d,1-3,4-3H2-alpha-tocopheryl esters were synthesized from d,1-3,4-3H2-alpha-tocopherol. They were acetate, propionate, butyrate, isobutyrate, caprylate, palmitate, acid succinate, benzoate, nicotinate, o-hydroxybenzoate, o-acetoxybenzoate, and pivalate. The hydrolysis of these esters with bile-pancreatic juice and with 9,000 x g supernatant of small intestine and liver homogenates of rats was examined. When these esters were incubated in small intestine or liver supernatants, hydrolysis occurred at a similar rate. In the incubation experiments, alpha-tocopheryl acetate, propionate, butyrate, isobutyrate, caprylate, palmitate, and acid succinate were classified as an easily hydrolyzable group. Alpha-tocopheryl benzoate and nicotinate were in a moderately hydrolyzable group. O-hydroxybenzoate and pivalate, which resisted hydrolysis, were in a scarcely hydrolyzable group. O-acetoxybenzoate was easily hydrolyzed to the o-hydroxybenzoate. Hydrolysis on straight chain fatty acid esters of alpha-tocopherol easily occurred in bile-pancreatic juice. In in vivo experiments, the lymphatic absorption rate of 6 esters, acetate, palmitate, acid succinate, nicotinate, o-hydroxybenzoate, and pivalate, was measured on thoracic duct fistula rats. Easily hydrolyzable esters were recovered mostly in lymph as alpha-tocopherol, whereas, an ester which strongly resisted hydrolysis, such as pivalate, appeared mainly unchanged. This fact suggested that hydrolysis of alpha-tocopheryl esters was not necessarily a prerequisite for intestinal absorption. The percentage of absorption of slowly hydrolyzed esters in lymph was relatively lower than that of moderately or easily hydrolyzable esters.     

Effect of medium-chain fatty acid positional distribution in dietary triacylglycerol on lymphatic lipid transport and chylomicron composition in rats

The present study was carried out to examine if the positional distribution of medium-chain fatty acid (MCF) in dietary synthetic fat influences lymphatic transport of dietary fat and the chemical composition of chylomicrons in rats with permanent cannulation of thoracic duct. Four types of synthetic triacylglycerol were prepared: (i) sn-1(3) MCF-sn 2 linoleic acid, (ii) interesterified sn-1(3) MCF-sn 2 linoleic acid, (iii) sn-2 MCF-sn-1(3) linoleic acid, and (iv) interesterified sn-2 MCF-sn-1(3) linoleic acid. A purified diet composed of equal amounts of the synthetic fat and cocoa butter was given to rats with permanent lymph duct cannulation. The positional distribution of MCF in the dietary fat had no significant effect on the lymph flow, triacylglycerol output, phospholipid output, lipid composition of chylomicrons, or the particle size. The positional distribution of MCF in the synthetic triacylglycerol was maintained in the chylomicron triacylglycerol. These results showed that MCF in the dietary triacylglycerol is transported into lymphatics and the positional distribution is well preserved in chylomicron triacylglycerol.     

Intestinal lymph absorption of butter,corn oil,cod liver oil,menhaden oil,and eicosapentaenoic and docosahexaenoic acid ethyl esters in rats

Adult male rats were surgically given a drainage catheter in the main mesenteric lymph duct. After an overnight fast, five groups of rats received intragastrically, in one bolus, butter, corn oil (CO), cod liver oil (CLO), menhaden oil (MO), or ethyl esters of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids (K80). Intestinal lymph was collected in these conscious animals, each hour during the first 6 h and in a single sample for the next 18 h. The absorption peak appeared earlier after MO and CO than after CLO administration. The quantities of triglycerides recovered during the first 6 h were significantly lower after butter (91 mg) and K80 (54 mg) administration than for the other three oils. No difference was observed between the vegetable oil and the two marine oils (CO=173 mg, CLO=148 mg, MO=180 mg). The total triglyceride recovered in 24 h was highest after CLO (410 mg) and lowest with K80 (146 mg). An increase in the weight percentage of some characteristic fatty acids of the lipid mixtures was observed: oleic acid for butter, oleic and linoleic acids for CO, EPA and DHA for CLO, MO, and K80. Chylomicrons were the largest with CO, more numerous and smaller with CLO, and the smallest with K80. Results obtained illustrated the relation between gastrointestinal hydrolysis, enterocyte biochemical events, and lymph triglyceride absorption profiles as related to the composition and distribution of triglyceride fatty acids.     

Dietary Guar Gum Reduces Lymph Flow and Diminishes Lipid Transport in Thoracic Duct-Cannulated Rats

Guar gum has a well-recognized hypolipidemic effect. This effect is thought to be due to the physicochemical properties of guar gum, which may cause changes in adsorption of lipids or the viscosity of the intestinal contents. Guar gum is a non-specific absorption inhibitor of any type of lipid-soluble compound. Permanent lymph duct cannulation was performed on rats to investigate the effects of dietary guar gum on lymph flow and lipid transport. Rats fed a 5% guar gum diet were compared with those fed a 5% cellulose diet, and lymph was collected after feeding. The water-holding capacity (WHC), settling volume in water (SV), and viscosity of guar gum were compared with those of cellulose. Rats fed with the guar gum diet had significantly lower lymph flow and lymphatic lipid transport than did rats fed with the cellulose diet. The WHC, SV, and viscosity of guar gum were significantly higher than those of cellulose. We propose that dietary guar gum reduces lymph flow and thereby diminishes lipid transport by means of its physicochemical properties related to water behavior in the intestine.     

Absorption by rats of tocopherols present in edible vegetable oils

The absorption of tocopherols (α, γ, and σ) and fatty acids from rapeseed (RO), soybean (SOO), and sunflower (SUO) oil, both from the natural oils and from the oils following moderate heating (180°C for 15 min), was measured in lymphcannulated rats. Oils were administered as emulsions through a gastrostomy tube, and lymph samples were collected for 24 h. The composition of tocopherols in oils and lymph fractions was measured by high-performance liquid chromatography, and fatty acids were measured by gas-liquid chromatography. The highest accumulated transport of α-tocopherol was observed after SUO administration, the lowest after SOO, with RO in between, corresponding to their relative contents (41.6±8.8, 32.7±5.0, and 24.9±4.3 μg at 24 h after administration of SUO, RO, and SOO, respectively). The calculated recoveries (in %) 24 h after oil administration were 21.4±4.5, 45.7±7.0, and 78.8±13.5 for SUO, RO, and SOO, respectively, suggesting that the absorption efficiency decreased when the α-tocopherol concentration increased. The recovery of α-tocopherol was higher than the recoveries of γ-and σ-tocopherol, indicating that the different tocopherols were not absorbed to the same extent or with similar rates. No differences between unheated and heated oils were observed in the absorption of tocopherols, whereas heating led to lower absorption of fatty acids, thus showing no direct association between absorption of tocopherols and fatty acids.     

Comparison of the effects of dietary sunflower oil and virgin olive oil on rat exocrine pancreatic secretion <Emphasis Type="Italic">in vivo</Emphasis>

The aim of this study was to investigate the functional consequences in vivo of adapting the rat exocrine pancreas to different dietary fats. Weanling rats were fed diets containing 10 wt% virgin olive oil or sunflower oil for 8 wk. We then examined resting and cholecystokinin-octapeptide (CCK-8)-stimulated pancreatic secretion in the anesthetized animals. To confirm a direct influence of the type of fat upon the gland, the FA composition of pancreatic membranes as well as tissue protein and amylase content were determined in separate rats. The membrane FA profile was profoundly altered by the diets, reflecting the type of dietary fat given, although this was not paralleled by variations in the pancreatic content of protein or amylase. Nevertheless, dietary intake of oils evoked different effects on in vivo secretory activity. Resting flow rate and amylase output were significantly (P<0.05) enhanced by sunflower oil feeding. Time course changes in response to CCK-8 infusion also showed a different pattern in each group. Secretion of fluid, protein, and amylase increased markedly in all animals, reaching a maximum within 20–40 min of infusion that was followed by a dramatic decline in both groups. In the sunflower oil group, this resulted in values reaching the resting level as soon as 60 min after CCK-8 infusion was begun. However, after the initial decline, olive oil group values showed a prolonged plateau elevation above the baseline (P<0.05) that was maintained for at least the infusion time. In addition, a positive correlation between flow rate and both protein concentration and amylase activity existed in the olive oil group, but not in the sunflower oil group. The precise mechanism by which these effects are produced remains to be elucidated.     

Intestinal absorption of retinol and retinyl palmitate in the rat. Effects of tetrahydrolipstatin

The aim of the present study was to characterize the intestinal absorption of retinol and retinyl palmitate in thoracic duct and bile duct fistulated rats and to investigate the effect of a simultaneously administered lipase inhibitor, tetrahydrolipstatin (THL). Absorption was determined as lymphatic recovery over a 24-hr period, including an initial 12-hr continuous intraduodenal infusion of either [11,12-³H]retinol or [11,12-³H]retinyl palmitate given in emulsified glyceryl trioleate or in mixed micellar solution of monoolein and oleic acid. From micellar dispersion, labeled retinol and retinyl palmitate were recovered in the lymph to 50–60% and both to the same extent. Administered in emulsified form, labeled retinol from fed retinyl palmitate was recovered to 47%, but retinol from fed retinol to only 18%. THL (10⁻⁴ M) in the infusate had no significant effect on the recovery of¹⁴C-labeled oleic acid. The recovery of label from emulsified glyceryl tri[1-¹⁴C]oleate was significantly decreased at this concentration of THL (76.5% vs 19.6% recovery). When administered in emulsified form, retinol absorption was not significantly affected by THL at 10⁻⁴ M, while retinyl palmitate absorption was very significantly decreased (5.0% compared to 47.8%). In the presence of THL, retinol absorption from retinyl palmitate in micellar solution was decreased (from 58% to 17%). Most of the retinol in the lymph extracts (72.2 to 91.3) was present as retinyl ester, regardless of the chemical and physical form of administration. Furthermore, THL did not induce any change in this pattern.     

The importance of the steric configuration of lysophosphatidylcholine in the lymphatic transport of fat

The importance of the steric configuration of lysophosphatidylcholine in the lymphatic transport of fat was investigated in bile fistula rats. It was found that the feeding of 1-palmitoyl-sn-glycero-3-phosphocholine increased the lymphatic output of phosphatidyl choline and triacylglycerol, while the feeding of 3-palmitoyl-sn-glycero-1-phosphocholine had no effect. In intestinal microsomes of the bile fistula rats, it was found that the lysophosphatidylcholine acyltransferase was stereospecific in acylating the 1-acyl-sn-glycero-3-phosphocholine enantiomer. The significance of these findings is briefly discussed.