Absorption Of Lysine Research Articles

Small intestinal absorption of amino acids and a dipeptide in pancreatic insufficiency.

In this study a perfusion technique has been used to investigate in vivo jejunal absorption and transmural potential difference evoked by the neutral amino acids phenylalanine (56 or 20 mmol/l) and glycine (20 mmol/l), the dibasic amino acid lysine (56 or 5 mmol/l), and a dipeptide glycyl-l-phenylalanine (20 mmol/l) in 11 children with pancreatic insufficiency due to cystic fibrosis and in three children with other causes of exocrine pancreatic insufficiency. Net absorption and potential difference evoked by phenylalanine in both cystic fibrosis and pancreatic insufficiency, and net absorption of glycine in cystic fibrosis were significantly reduced; but the absorption of lysine and glycyl-l-phenylalanine was normal. Absorption of the constituent amino acids from the dipeptide was normal or increased in cystic fibrosis. Thus, these studies show a defect in active absorption of neutral amino acids in cystic fibrosis with pancreatic insufficiency and exocrine pancreatic insufficiency. We speculate that pancreatic factors participate in neutral amino acid absorption.

Chemical and Functional Properties of Peanut and Rice Bran Flour Blends

Abstract Plant proteins are being added to foods and beverages to improve nutritive value or change functional properties. No one protein can supply all the desirable characteristics. Blends of peanut and rice bran flours in 1:3, 1:1, and 3:1 ratios had different protein solubility than the original materials. Methionine, lysine, available lysine, hydration capacity, and fat absorption increased as the amount of rice bran increased. Emulsifying capacity and emulsion stability were highest in all blends.

Sustained Pectin Ingestion Delays Gastric Emptying

The effects of sustained fiber ingestion on gastric emptying glucose tolerance, hormone responses, and jejunal absorption of glucose and lysine were studied in healthy volunteers. Subjects were placed on a low-fiber (3 g) diet for 2 wk, followed by 4 wk of an isocaloric diet supplemented with 20 g/day of either apple pectin (7 subjects) or alpha-cellulose (6 subjects). At the conclusion of each dietary period subjects ingested a low-fiber breakfast surface-labeled with 99mtechnetium sulfur-colloid. Gastric emptying half-time, plasma glucose, calcium, phosphorus, insulin, glucagon, gastrin, human pancreatic polypeptide, and motilin were determined. Gastric emptying half-time was prolonged approximately twofold after pectin supplementation (p less than 0.005) and returned to normal 3 wk after discontinuing pectin supplementation. Cellulose supplementation did not alter the gastric emptying rate. Plasma glucose, calcium, phosphorus, and hormonal responses to the meal were unchanged after either pectin or cellulose supplementation. Pectin ingestion did not impair intestinal absorption of glucose or lysine. In contrast to sustained cellulose ingestion, sustained pectin ingestion slows the gastric emptying rate; the mechanism underlying this adaptive effect is unknown.

The rate of absorption of synthetic lysine and dietary protein in the upper half of the small intestine of pigs.

The aim of the present work was to estimate the rate of lysine absorption in the upper part of the small intestine as related to the absorption of total nitrogen and other amino acids in pigs given feed (barley + sesame meal) supplemented with lysine and fed once or 4 times daily. The experiments were carried out on 6 pigs fitted with reentrant cannulas sited in 3 of them about 4 m and in an other 3 about 9 m distal to the pylorus (mean intestine length was about 18 m). The frequency of feeding influenced the rate of flow of total nitrogen and lysine through the intestine. The content of lysine in the digesta (g/16 g N) during the first 5 hours after morning feeding, and particularly between 8.00-10.00 h, was much higher with once daily than with four times daily feeding while during the subsequent 15 hours the reverse was true. The absorption of lysine occurred at a faster rate than that of the other amino acids and was closest to that of arginine and methionine. On the whole, the net absorption rate of essential amino acids in the upper part of the intestine of pigs was as follows: Lys, Met greater than His, Phe, Leu greater than Trp, Ile, Val greater than Thr (Cys). It seems that the more uniform passage through and absorption from the alimentary tract of synethetic lysine and dietary protein, observed at frequent feeding could contribute to their better utilization for protein synthesis in the organism.

In vitro stability, in vivo hydrolysis, and absorption of lysine and methionine from polymerized amino acid preparations.

In vitro stability, in vivo hydrolysis, and absorption of lysine and methionine from polymerized amino acid preparations.

Different pathways for lysine transport across neonatal pig intestine.

1. Undirectional fluxes of lysine, presented free and in the form of a dipeptide, have been measured in vitro using the small intestines of pigs taken during the first 2 weeks of post-natal life. 2. The concentration dependence of free lysine transfer to the serosal surface of new-born pig intestine (Jms) can be described as the sum of a saturable (Km 0.2 mM; Jm 3 n- mole cm-2 in-1) and a non-saturable (1.0 n-mole cm-2 min-1 mM-1) component. 3. The dipeptide isoleucyl-lysine was hydrolysed completely during transfer to the serosal surface of intestines taken at all stages of development. The concentration dependence of peptide-derived lysine transfer can be described as if it took place through a single saturable process (Km 5 mM; Jm 27 n-mole cm-2 min-1). 4. The mucosa to serosa transfer of free lysine fell to a half and that of peptide-derived lysine fell to a quarter, during the first 8 days of post-natal life. The decline in peptide-derived lysine transport correlated with changes in peptide hydrolase activity, measured in homogenates of intestinal mucosa using isoleucyl-lysine as substrate. 5. The new-born pig intestine transported lysine derived from isoleucyl-lysine twice as quickly as from lysyl-isoleucine. Lysine and isoleucine did not inhibit the transfer of isoleucine and lysine derived from isoleucyl-lysine. The transport of lysine, but not isoleucine, from isoleucyl-lysine took place more quickly than from equimolar solutions of the free amino acids. 6. It is suggested from these results that lysine and isoleucyl-lysine use different pathways when crossing the intestinal mucosa. Attempts are made to assess the probable contributions made by these pathways to the total absorption of lysine taking place during neonatal development.

Lysine fluxes across the jejunal epithelium in lysinuric protein intolerance.

Lysinuric protein intolerance (LPI) is one of a group of genetic diseases in which intestinal absorption of the diamino acids lysine, arginine, and ornithine is impaired. In LPI, the clinical symptoms are more severe than in the kindred disorders. The mechanism of lysine absorption was, therefore, investigated in vitro on peroral jejunal biopsy specimens in seven patients with LPI and 27 controls. The lysine concentration ratio between cell compartment and medium was significantly higher in the LPI group (mean+/-SEM, 7.17+/-0.60) than in the controls (5.44+/-0.51). This was also true for the intracellular Na concentration (LPI, 73.6+/-10.8 mM; controls 42.3+/-3.7 mM). The rate of unidirectional influx of lysine across the luminal membrane was Na dependent and was the same in the two groups. In the absence of an electrochemical gradient, net transepithelial lysine secretion was observed in LPI. This was entirely the result of a 60% reduction of the unidirectional flux from mucosa to serosa. Calculation of unidirectional fluxes revealed the most striking difference at the basolateral membrane, where the flux from cells to serosa was reduced by 62% and the corresponding permeability coefficient reduced by 71%. A progressive reduction in short-circuit current appeared in the epithelia of all four patients with LPI tested after addition of 3 mM lysine. Thus, LPI appears to be the first disease in which a genetically determined transport defect has been demonstrated at the basolateral membrane.

The protein digestibility and amino acid absorption in various segments of the digestive tract of pigs. 6. Results of the application of 15N-lysine

From two fattening pigs (average live weight 63 kg) with re-entrance cannulae both in the duodenum and the ileocecal region, the intake, the excretion and the flow rates of nitrogen, 15N, lysine and 15N-lysine are measured after the oral application of 15N-lysine as supplement of a wheat-wheat gluten diet. A scheme of the lysine metabolism of pigs is drawn on the basis of the measured values. The absorption of synthetic and native lysine as well as the endogenous and exogenous lysine contents of the duodenal and ileum chyme are estimated.

Untersuchungen über die Proteinverdaulichkeit und Aminosäurenresorption in verschiedenen Abschnitten des Verdauungstraktes beim Schwein

The intake, excretion and the rate of flow of protein, methionine and 35S were measured at four pigs (live weight 63 kg) with re-entrant cannulae in the duodenum and the ileocecal region after the oral application of 35S-methionine and the feeding with a wheat + wheat gluten + lysine resp. a protein-free diet over a period of 7 days. From the measured values one pattern each for the N- and the methionine metabolism was laid down with the help of the compartment model, and the endogenous and exogenous levels of protein resp. methionine in the duodenum, the ileum and in feces were estimated.

Formaldehyde treatment of concentrate diets for sheep. III.* Absorption of amino acids from the small intestine

The effects of formaldehyde treatment of barley/soybean meal diets on the flow of amino acids to the small intestine, their release and absorption there, and their levels in jugular plasma were studied at four protein levels in fistulated crossbred sheep. There were substantial losses of amino acids during passage through the stomach at the highest protein level which were prevented by formaldehyde treatment; the net gains of amino acids observed with the lower protein diets were enhanced by treatment. There were no statistically significant effects of treatment on the proportions of the individual amino acids apparently absorbed in the small intestine, but a tendency for the values to decrease for the highest protein diet suggested that this diet was overtreated. This was confirmed by calculation of the true digestibilities in the small intestine: the true digestibility of true protein in the small intestine was 0.74 for the treated high protein diet and 0.81 for all the other diets. Of the individual amino acids, only lysine was adversely affected by treatment; however, despite reduced intakes, the net absorption of lysine was equal to or greater than that achieved with the untreated diets at all but the lowest protein level. Formaldehyde treatment was associated with substantial increases in the concentration of ε-N-methyl-lysine in plasma. As the amount of protein absorbed from the small intestine increased to about 110 g/day, the concentrations in plasma of the amino acids normally present in protein declined to a minimum or remained steady; thereafter, except for lysine, the concentrations increased. ____________________ *Part II, Aust. J. Agric. Res. 28: 1069 (1977).

Hyperdibasicaminoaciduria in a Turkish infant without evident protein intolerance

The first patient of Turkish descent with hyperdibasicaminoaciduria is described. Recurrent diarrhea was observed only during the first three months of life. The infant exhibited low plasma levels of ornithine and arginine. Intestinal absorption of lysine was decreased. Hyperammonemia was noticed only after an i.v. alanine load. It was prevented by addition of arginine.

Kinetics of the absorption of amino acids by the rat intestine in vivo

The kinetics of l-phenylalanine and l-lysine absorption by the rat small intestine in vivo have been studied by perfusing intestinal segments and monitoring simultaneously the uptake of the substrate into the intestinal tissue and its disappearance from the perfusate. The rate of phenylalanine disappearance is a linear function of the substrate concentration. Its uptake into the tissue is rapid and obeys saturation kinetics, but is not concentrative. Both tissue uptake and disappearance rate can be inhibited by leucine or methionine, but are not influenced by hydrophilic neutral or dibasic amino acids. Lysine disappearance from the perfusate and its uptake into the tissue both display saturation kinetics. Lysine transport is quantitatively smaller than that of phenylalanine. Both uptake and disappearance are inhibited by arginine and leucine, but are unaffected by other neutral amino acids or sugars. To analyse the kinetic results, integrated equations were developed to express the final concentration in the perfusate in terms of the original concentration. The disappearance rate was considered as a mixed process (saturable and non-saturable in parallel) in a one-compartment system, and the uptake by the tissue was treated as a two-compartment system in which the amino acid entered the cells by a mixed process but left them by a pure non-saturable mechanism. The results concerning disappearance from the lumen are compatible with the one-compartment model. Phenylalanine absorption can be described by a major non-saturable component and a minor saturable one, while lysine absorption occurs almost entirely by a saturable process. The two-compartment model does not adequately describe the tissue uptake results.

The effect of pregnancy and lactation on the absorption of zinc and lysine by the rat duodenum in situ.

1. The absorption of zinc by the duodenum of the rat was greatly enhanced at late stages of pregnancy and during lactation. 2. During pregnancy no increase in lysine uptake could be demonstrated, but during lactation, when further increases in Zn absorption occurred, uptake of lysine was increased. 3. The increased absorption of Zn at different stages of pregnancy and lactation appeared to be related to the demand made by the developing foetuses and post-natal offspring.

The effect of sodium sulphate and methionine on the utilisation of non‐protein nitrogen by laying hens

1. The response of layers to adding diammonium citrate (DAC), sodium sulphate or methionine to a basal diet containing 136–3 g protein/kg was determined. 2. Supplementing the diet with DAC equivalent to 25 g protein/kg did not improve egg production, the efficiency of food utilisation, egg weight, nitrogen retention or the apparent absorption of lysine and methionine; increases in food intake and in the concentration of methionine in the serum and liver were observed. 3. Adding sodium sulphate, alone or with DAC, did not affect the variables noted above. 4. Supplementation of the basal diet with methionine increased egg production, egg weight, food intake and the concentrations of lysine in the serum and liver. 5. It is concluded that the supplemental NPN was used only in serum protein synthesis.

Effect of authentic and natural vitamin C and carotene on amino acid absorption

The effect of vitamin C or carotene either from authentic or natural sources on absorption of lysine, glycine and methionine was evaluated. Results revealed that maximum absorption of these amino acids was reached at different intervals from the orally given dose. Addition of ascorbic acid enhanced amino acid absorption and this effect was maximum in case of methionine. Carotene brought about variable effect to the three amino acids tested. Pepper, parsley, or orange juices did not affect the extent of intestinal lysine absorption. Pepper juice enhanced absorption of methionine in contrast to orange and parsley. Glycine absorption was markedly enhanced by addition of orange juice. Ascorbic acid suppelementation to dietary constituents is recommended for better utilization of proteins.

Experimental lead poisoning and intestinal transport of glucose, amino acids, and sodium.

Juvenile rats fed a diet containing 1% lead acetate for 7 weeks, in addition to an impaired growth rate and renal function derangements, suffered malabsorption of glucose and certain amino acids, as assessed by an in vivo perfusion technique. The reduction in glucose absorption ranged between 10% and 31% when the carbohydrate was pumped in concentrations of 2-80 mM. This alteration was compatible with a noncompetitive type of transport inhibition. The intestinal absorption of glycine, lysine, and phenylalanine were, respectively, decreased 22, 18, and 15% when these amino acids were present at 1 mM levels. Sodium transport was severely reduced (57.6 +/- 17.9 (SEM) vs. 124.2 +/- 17.4 muEq/min-cm) and intestinal mucosa (Na+-K+)-ATPase was concomitantly lower in the lead-intoxicated rats (186.4 +/- 19.0 vs 268.4 +/- 29.8 nmol P/min-mg protein). However, this enzyme was not altered in liver and kidney. Furthermore, intestinal mucosa fructose-1,6-diphosphatase, succinic dehydrogenase, pyruvate kinase, and tryptophan hydroxylase were not different in experimental and control animals. These studies substantiate the presence of functional and biochemical abnormalities in the intestinal mucosa of young rats when fed substantial amounts of a soluble lead salt. It is, therefore, reasonable to accept the possibility that physiologic damage occurs in tissues directly subjected to high and persistent levels of a toxic agents, as it occurs in other organs, underscoring the parallelism between transport mechanisms at the renal and intestinal levels.

Absorption of different amino acids by an intestinal preparation from normal rats and from rats exposed to supralethal X-irradiation.

Absorption of different amino acids [lysine, alpha-amino isobutyrate (AIB), methionine, alanine, glycine] was studied in an intestinal in vivo preparation from normal and X-irradiated rats (1 and 3 days after 2000 R). Absorption of amino acids under loading and in presence of other amino acids was also followed. Lysine and AIB absorption follow a saturation kinetics with a maximal velocity of 35 and 85.6 micronmoles/min and a Kt of 10 and 67 micronmoles for lysine and AIB respectively. Interference in absorption exists not only between amino acids of the same class, but also by lysine on neutral amino acids. One day after irradiation, absorption is normal or even enhanced, although active transport appears impaired as indicated by the increase in Kt. Three days after exposure absorption, particularly the active one, is severely depressed. This is indicated by the low Vm and high Kt as well as by the fact that loading has little influence on absorption.

Nutritional evaluation of wheat. 5. Disappearance of components in digesta of pigs prepared with two re-entrant cannulae

SUMMARY1. Three pigs prepared with re-entrant cannulae in the proximal duodenum and terminal ileum were used to study flow rate of nitrogen, and digestion and absorption of dry matter, nitrogen, gross energy and starch. The pigs were given a semi-purified diet, a hard wheat diet and a soft wheat diet. These were approximately isonitrogenous.2. Nitrogen content of insoluble dry matter of duodenal digesta was much higher on the semi-purified diet than on the wheat-based diets.3. Apparent digestibilities of dry matter, energy and nitrogen in the small intestine were in the order semi-purified diet > hard wheat > soft wheat although differences were not statistically significant. Similar results were obtained for total digestibility of these components.4. Absorption of most amino acids from the small intestine was higher for casein in the semi-purified diet than for wheat protein. Significantly more lysine, arginine, isoleucine and tyrosine were absorbed from hard than from soft wheat.5. With all diets there was almost complete digestion of starch in the small intestine.6. There was little digestion of nutrients in the large intestine, and thus digestibilities calculated from faecal analyses showed similar trends to those calculated from analyses of digesta from the terminal ileum. Most values compared favourably with those reported elsewhere for digestibilities of amino acids in wheat.7. It was concluded that casein was superior to the wheat proteins but that protein of hard wheat was of better quality than that of soft wheat when evaluated by ileal recovery of animo acids, due largely to a greater absorption of lysine.

Lysine Malabsorption Syndrome: A New Type of Transport Defect

A 21-month-old girl with physical and mental retardation is described. She excreted an increased amount of lysine in urine but no excessive quantities of arginine, ornithine, or cystine. Serum level of lysine was found to be low but the levels of the other amino acids were within normal limits. The endogenous renal clearance rates of amino acids showed a marked high value of lysine and normal values of the other dibasic amino acids. Oral loading test of amino acids revealed an imparied absorption of lysine and normal absorption of arginine, ornithine, and cystine in the intestine. These results indicate a specific defect in transport of lysine in the intestine as well as in the renal tubule.

INFUSION OF LYSINE PER ABOMASUM IN STEERS: DIETARY, ABOMASAL AND PLASMA LEVELS OF AMINO ACIDS OF STEERS FED CONTINUOUSLY OR TWICE A DAY

Eight Holstein steers fitted with abomasal cannulae were used in two 4 × 4 latin square designs. A corn-based, corn gluten-meal-supplemented diet was fed to four steers continuously (part A), and to four steers twice a day (0700 h and 1900 h) (part B). Within each latin square, lysine hydrochloride was infused per abomasum to provide the equivalent of 0.0, 3.0, 6.0 and 9.0 g lysine per day. Nitrogen (N) balance decreased, urinary N (percent of N intake), and abomasal N (percent of N intake) increased as lysine infusion was increased from zero to 9 g per day (part A). In part B, N digestibility was reduced and the concentrations of arginine, leucine, isoleucine, methionine, cystine (cysteine), phenylalanine and tyrosine increased significantly (P < 0.05) at 6 g lysine per day. Lysine infused per abomasum of steers was of no benefit to the animal with respect to several of the N parameters. The presence of a relatively high leucine concentration available for absorption in the small intestine may have influenced lysine absorption. The use of continuous feeding as an experimental tool reduced the interactions encountered between lysine infusion and the concentration of amino acid (AA) in the plasma. The continuous feeding method proved useful in defining the effects of dietary N on rumen microbial metabolism and subsequently on AA metabolism in the ruminant.