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Unitat de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, 08028 Barcelona, Spain
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ABSTRACT |
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Top
Abstract
Introduction
Methods
Results
Discussion
References
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The influx of L-lysine into apical vesicles from the chicken jejunum occurs through two systems, one with low Michaelis constant (Km) and features of system b0,+ and the other with relatively high Km for L-lysine and with properties of system y+. In the present study the effect of a lysine-enriched diet (Lys, containing 68 g L-lysine/kg dietary protein, control animals 48 g/kg) on L-lysine uptake through both transport systems was investigated. Results show that 1) lysine enrichment had no effect on either body weight or the efficiency of food utilization. 2) In Lys-fed animals, the mediated L-lysine influx was best fitted to the two-system model with y+ and b0,+ activity. 3) In the presence of an Na+ gradient, total L-lysine uptake is significantly higher in Lys-fed animals than in control birds (about 40% increase). 4) Lys diet increases Kmb0,+ 6-fold (KSCN gradient) and 12-fold (NaSCN gradient) and maximum velocity (Vmax) by 6- and 20-fold, respectively. The effects of Lys enrichment on the y+-like system are only observed on the Vmax and in the presence of a Na+ gradient (30% increase). 5) Na+ is involved in the activation of the transport process in the Lys-fed chickens, but there is no correlation between external Na+ concentration and L-lysine influx. In conclusion, both b0,+- and y+-like transport systems are upregulated by dietary lysine but with different kinetic profiles; the high-capacity y+-like carrier shows a Vmax increase without changes in Km, whereas the low-capacity b0,+-like system shows an increase in Vmax as well as in the Km.
system b0,+; system y+; adaptive regulation
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INTRODUCTION |
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Top
Abstract
Introduction
Methods
Results
Discussion
References
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AN ESSENTIAL AMINO ACID with high significance in chicken development and performance is L-lysine (8, 15, 16, 19). This amino acid is taken up by the small intestine of the chicken by mechanisms that have been recently described; in the apical membrane there are two carrier systems differing in their kinetic properties and in the way they interact with neutral amino acids and which have been identified as systems b0,+ and y+ (26). Similar transport systems have been characterized in human intestinal epithelial Caco-2 cells (25).
Some reports point out that L-lysine also has a role in the improvement of weight gain and food efficiency in birds when its content in the diet is increased (20). We wanted to test this hypothesis by feeding chickens with a lysine-enriched diet to see whether we could relate the L-lysine content of the diet to nutritional parameters and to the absorptive function of the small intestine and whether the eventual changes in the intestinal transport of L-lysine induced by the diet agree with Diamond's adaptive regulation hypothesis. Ferraris and Diamond (10) claim that dietary constituents regulate their own transport, albeit the patterns of regulation may differ according to the role of the transported substrate in metabolism, i.e., energetic, essential, or both. Transport regulation by dietary content is attributed to an increase in the number of specific carriers (7, 9, 30) and not to unspecific factors, such as membrane permeability, epithelial surface area, or ionic gradient. We wanted to see to what extent the pattern of intestinal L-lysine transport by the chicken intestine bears out the postulates of the hypothesis in fully adapted birds.
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METHODS |
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Top
Abstract
Introduction
Methods
Results
Discussion
References
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Animals and diets. One-day-old male Label chickens were housed in cages in controlled temperature and humidity conditions, with a 18:6-h light-dark schedule. Animals were fed ad libitum for 1 wk with a standard diet and then randomly divided into two groups and fed for 5 additional wk with either the same diet (control diet) containing 48 g L-lysine/kg dietary protein or a diet enriched with L-lysine (Lys diet) containing added L-lysine to reach a value of 68 g/kg dietary protein. Food consumption and body weight were measured twice weekly throughout the experiment. Diets were isoenergetic (13 MJ/kg food) and formulated to contain 20% protein, 5.52% lipid, and 38.5% carbohydrate. The composition in essential amino acids was (g/kg diet) 5 DL-methionine, 9.8 L-isoleucine, 23 L-leucine, 8 L-threonine, 13.2 L-arginine, 2.1 L-tryptophan, 9.1 L-methionine-L-cysteine, and either 9.6 g/kg (control) or 13.6 g/kg (Lys diet) of L-lysine.
Preparation of brush-border membrane vesicles.
Membranes were prepared from the jejunum of 6-wk-old chickens fed
either control diet or Lys diet. Animals were killed in the morning by
neck fracture, without previous starvation. The jejunum (from the end
of the duodenal loop to the Meckel diverticulum) was removed,
immediately flushed with ice-cold saline, opened lengthwise, frozen in
liquid N2, and stored at
80°C.
Protein and enzyme assays. Sucrase, a brush-border marker enzyme, and Na+-K+-adenosinetriphosphatase (ATPase), a basolateral marker enzyme, were routinely assayed, according to Dahlqvist (3) and Del Castillo and Robinson (4), respectively, in both dietary treatments. Protein was determined using the Bio-Rad protein assay, with bovine serum albumin as standard.
Transport studies. L-Lysine uptake was assayed for time periods ranging from 1 s to 1 h at 37°C using the rapid- filtration technique previously described (26). The vesicles were incubated under isotonic conditions (320 mosmol/l) in an incubation medium containing 100 mmol/l mannitol, 0.2 mmol/l MgSO4 · 7H2O, 0.02% LiN3, and 20 mmol/l HEPES-Tris, pH 7.4, 100 mmol/l of a salt (NaSCN or KSCN), and the appropriate concentration of labeled L-lysine (5-10 µmol/l) or D-glucose (100 µmol/l) as substrates. In experiments requiring salt equilibration across the membrane, vesicles were preequilibrated for 30 min in 100 mmol/l of the salt before being added to the incubation medium. Experiments were performed in triplicate using vesicles from different batches.
Some of the results obtained with the standard (control) diet, designed to discover the properties of L-lysine uptake in the chicken, were the subject of a previous publication (26). These results have been included in the tables and figures when necessary to facilitate comparison with the results of the present article.NEM treatment. The effect of N-ethylmaleimide (NEM) on 5 and 100 µmol/l L-lysine uptake was studied as previously described (26). Brush-border membrane vesicles (BBMV) were preincubated with 0.5 mmol/l NEM for 30 min at 25°C. To wash off the inhibitor, vesicles (either treated or not with NEM) were sedimented by high-speed centrifugation (12,000 g), and the pellets were resuspended in isolation medium. The resulting suspension was used for transport experiments. Nontreated vesicles ran parallel to NEM-treated vesicles in both diets.
Chemicals. L-[U-14C]lysine and D-[U-14C]glucose were obtained from New England Nuclear Research Products (Dreieich, Germany). Unlabeled reagents, including the lysine used for diet enrichment, were from Sigma Chemical (St. Louis, MO). Reagents used to determine enzyme activities were from Boehringer (Mannheim, Germany).
Transport equations. The kinetic parameters of L-[14C]lysine transport were determined by nonlinear regression analysis (Enzfitter, Biosoft, Cambridge, UK), according to the strategy described by Devés et al. (6). The approach is based on the use of the relative transport rate v/vo, defined as L-[14C]lysine uptake in the presence and absence of inhibitor. When two transport systems are present and the substrate concentration is low, the relative transport rate is given by
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(1) |
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(2) |
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(3) |
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Data analysis. The data were reported as means ± SE. All data were compared using analysis of variance except for kinetic studies, where Student's t-test was used. In both cases P < 0.05 was considered statistically significant.
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RESULTS |
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Top
Abstract
Introduction
Methods
Results
Discussion
References
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Effect of diets on body weight. One-week-old chicks had a mean weight of 80.2 ± 2.0 g. After 5 wk the weight of the birds receiving the control diet was 1.14 ± 0.02 kg (n = 41) and that of the lysine-enriched diet (Lys diet) was 1.17 ± 0.02 kg (n = 44). These values indicate that there is no effect of a lysine-enriched diet on body weight. The efficiency of food utilization, expressed as gram weight gain divided by gram food intake, was also the same during the 5-wk period (0.32 ± 0.02 in control diet and 0.34 ± 0.01 in Lys diet).
Properties of BBMV. Vesicles prepared from the jejunum of both control and Lys diet-fed chickens showed similar sucrase and Na+-K+-ATPase enrichment factors (Table 1), indicating low basolateral membrane contamination. To check the functional properties of BBMV and to detect any dietary effect on monosaccharide transport, D-glucose (100 µmol/l) uptake was examined under zero-trans 100 mmol/l NaSCN or KSCN (intravesicular salt concentration equals 0 mmol/l and extravesicular salt concentration equals 100 mmol/l). Table 1 shows that vesicles behave as expected and that no differences were observed between the control diet and the Lys diet-fed animals. The values at equilibrium show no dietary effects on either vesicular volume (around 0.6 µl/mg protein) or D-glucose membrane binding.
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Time course of L-[14C]lysine. Figure 1 shows time-dependent uptake of L-lysine (100 µmol/l), expressed as a percentage of the 60-min uptake value, in the presence of an inwardly directed Na+ gradient (100 mmol/l NaSCN). The overshoot appears after 20 s of incubation and is higher in vesicles from Lys diet than from control birds. Experiments performed in the absence of Na+ (KSCN gradient) showed no differences between diets (data not shown). Values obtained at equilibrium (about 80 pmol/mg protein) indicate no dietary effects on vesicular volume nor on L-lysine fixation to the membrane, either in the presence of Na+ or K+.
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Kinetics of L-lysine transport. Kinetic parameters were calculated from 10 µmol/l L-[14C]lysine influx, under zero-trans NaSCN or KSCN gradients (100 mmol/l), in the presence of increasing unlabeled L-lysine or L-methionine concentrations (0-20 mmol/l) (Fig. 2). The kinetic analysis was performed from 3-s incubation data. In preliminary experiments, it was shown that L-lysine influx is linear for at least 5 s and that binding to the membrane is not modified by the thiocyanate salt, in either dietary treatment (data not shown).
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1 · 3 s1 and Lys 29.3 ± 2.2).
However, when the experiments were carried out in the presence of
Na+, total uptake in Lys animals
(40.8 ± 3.1) was higher than in control birds (30.1 ± 4.2).
NEM treatment.
To validate the kinetic effects reported, experiments were performed in
NEM-pretreated vesicles to inhibit the
y+ activity (5). In these
conditions
Vmaxb0,+
was calculated from
Kmb0,+
values and from 5 µmol/l
L-[14C]lysine
influx in the absence of unlabeled amino acid. The
Vmax (expressed
in pmol · mg
protein1 · 3 s1) was still higher in
Lys-fed animals than in control animals, and an
Na+ effect was also observed in
the Lys diet (Lys diet, KSCN 30.0 ± 2.15 and NaSCN 70.8 ± 14.2;
control diet, KSCN 5.5 ± 0.67 and NaSCN 4.7 ± 0.6). Moreover,
experiments performed in the presence of NEM, with
L-lysine at a much higher
concentration (100 µmol/l), also show an effect of external
Na+ (KSCN 30.9 ± 1.1 and NaSCN
60.1 ± 3.4 pmol · mg
protein1 · 3 s1), which supports the
kinetic predictions for the
b0,+-like system in Lys-fed
animals.
Effect of Na+ gradient. As shown before, Na+ is relevant in the uptake process of L-lysine by the brush border. To investigate the possible existence of an Na+-dependent component in Lys-fed animals, initial rates of L-lysine transport were determined in the presence of increasing zero-trans NaSCN gradients, ranging from 0 to 100 mmol/l. Figure 3 shows that Na+ has a stimulating effect, which is maximal at already low Na+ concentrations (0.25 mmol/l). Therefore, there is no correlation between the external Na+ concentration and the rates of L-lysine transport in the Lys diet-fed chickens. These results indicate that L-lysine is not cotransported with Na+, neither in control nor in Lys-fed animals, but they strongly suggest an activation effect of Na+ on L-lysine influx related to dietary lysine.
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Experiments in preequilibrated vesicles.
In NaSCN preequilibrated vesicles (intravesicular NaSCN concentration
equals extravesicular NaSCN concentration equals 100 mmol/l)
L-lysine uptake (10 µmol/l)
was significantly higher in Lys animals (9.3 ± 0.2 pmol · mg
protein1 · 3 s1,
n = 4) than in control chickens (7.0 ± 0.4 pmol · mg
protein1 · 3 s1,
n = 3). This effect was
not observed in vesicles equilibrated with KSCN (Lys 6.72 ± 0.5, control 6.0 ± 0.7 pmol · mg
protein1 · 3 s1,
n = 3), indicating that
Na+ "facilitates"
L-lysine movement across the
membrane. In both conditions no overshoot is observed and the
equilibrium values (60 min) are not modified by diet or ionic
composition.
BCH inhibition. Because our results clearly show that cis Na+ has a stimulatory effect on L-lysine uptake, we wanted to prove the existence of Na+-dependent transport for cationic and neutral amino acids (B0,+-type system). B0,+ activity differs from b0,+ activity in its sensitivity to bicyclic amino acids, such as 3-amino-endo-bicyclo[3.2.1]octane-3-carboxylic acid or 2-amino-endo-bicyclo[2.2.1]heptane-2-carboxylic acid (BCH) (28). Figure 4 shows the cis effects of 1 mmol/l BCH on 5, 100, and 200 µmol/l L-lysine influx, in the presence or in the absence of Na+. Results show that there is no specific effect of BCH on the Na+-stimulated L-lysine influx, indicating the lack of B0,+ activity in Lys animals.
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DISCUSSION |
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Top
Abstract
Introduction
Methods
Results
Discussion
References
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Dietary treatment. Following the recommendations of the National Research Council (22) for broilers, a control diet containing 20% protein and 0.96% L-lysine was formulated to assure that the amount of L-lysine would not be limiting for animal growth and performance. Because Morris et al. (20) found an improvement in body weight gain and in the efficiency of food utilization by increasing L-lysine content from 0.94 to 1.27%, a lysine-enriched diet was designed containing 1.36% L-lysine, i.e., a 42% increase relative to the control diet. In these conditions, the dietary effects observed should be attributed to either diet supplementation of this specific amino acid or to an effect resulting from the different L-lysine/protein ratio between controls (0.048) and the Lys group (0.068).
Our results show, however, that the protocol employed in the present study had no influence on either chicken growth or on food utilization. This was not totally unexpected because other laboratories have reported controversial results in lysine-supplemented animals; for example, Leclerq et al. (15) have shown that chickens selected for rapid growth are less sensitive to L-lysine levels in the food than lean-line birds. Although L-lysine enrichment was not reflected in conventional nutritional parameters, the higher luminal L-lysine concentration was found to exert a significant effect on specific transport systems that participate in lysine absorption.Properties of L-lysine transport. The y+- and b0,+-like systems are involved in L-lysine transport in the chicken jejunum. System b0,+ shows low Km and low capacity for L-lysine transport, whereas y+ has higher Km and a relatively high transport capacity (26). In addition, both transport systems are able to interact with L-methionine albeit with different inhibition constants (Kiy+ is much higher than Kib0,+, Table 2). Recent experiments carried out in these membranes, using L-methionine as substrate (23), strongly indicate the presence of only two pathways sensitive to L-lysine inhibition and with kinetic properties closely similar to those described for L-lysine (Km of L-methionine similar to its Ki against L-lysine and vice versa).
In the chicken, the contribution of both systems to mediated transport in control conditions (calculated for a 10 µmol/l L-lysine concentration) is 12% for b0,+ and 88% for y+. This profile differs from that found in human epithelial Caco-2 cells, where b0,+ and y+ contribute 64 and 36%, respectively (25). L-Lysine transport was found to be sensitive to membrane potential, although the effects are mainly seen in relatively long-term (20-s) incubations, probably indicating a slow movement of L-lysine across the membrane (26). Such a slow rate of influx is enhanced by external Na+ as indicated by the significant increase in Vmaxy+. This effect can be attributed to a rise in the inside negative potential due to the different membrane permeability to Na+ and K+. The effect of Na+ is further potentiated by the lysine-enriched diet. A lysine-enriched diet increases the intestinal L-lysine influx in the presence of Na+ because the Lys diet enhances system y+-like sensitivity to Na+ and induces Na+ sensitivity in the b0,+ transport activity. Because system b0,+ does not seem to be greatly affected by the membrane potential, the role of Na+ can be better interpreted as an effect on the efficiency of the transport process. The possibility of a change in the membrane permeability to Na+ in Lys-fed animals was rejected because Na+-dependent, D-glucose uptake, a process that is highly sensitive to membrane potential (21), was not affected by lysine enrichment. In the absence of Na+ time-dependent L-lysine transport is not modified by the dietary treatment, and the kinetic constants of the y+-like system are not affected by lysine enrichment either. The b0,+-like system shows a six- to sevenfold increase in Vmax and Km; these changes may explain why dietary lysine has little effect on total L-lysine influx when K+ substitutes Na+. Under a Na+ gradient, Lys diet adaptation has a much greater effect on the kinetic constants of the b0,+- than of the y+-like system. In these conditions, the change in the relative contribution of each system to L-lysine uptake (manifested by the significant increase in F), confirms the increase in the contribution of the b0,+-like system. This dietary effect, in addition to the dietary increase in the Vmaxy+, results in a higher total L-lysine influx. It is worth noting that the effects of Lys diet are also observed in preequilibrated vesicles, in the absence of ionic or membrane potential gradients. The effects of the Lys diet on L-lysine transport are fully manifested with Na+ present in the incubation medium, suggesting that dietary lysine stimulates a regulated Na+-dependent transport system with high selectivity for cationic amino acids, similar to what was reported by Wolffram et al. (29) in rats fed a high- protein diet. This would be another example of paired transport system for cationic amino acids that have similar substrate selectivity but differ only in their Na+ dependence. The possible existence of a B0,+-like transport activity was studied using BCH as specific inhibitor (28). The results show that this analog inhibits lysine uptake to a similar extent (about 30%) both in the presence and in the absence of Na+, thus weakening the existence of a B0,+ carrier. The inhibition observed with BCH is consistent with the results of Bertran et al. (2) showing an interaction of high BCH concentrations with the b0,+ activity in Xenopus oocytes. Na+ is not required for the activation of L-lysine transport across b0,+- or y+-like systems, but influx in the presence of Na+ is greater than in its absence. This stimulatory effect of Na+ is already seen at low Na+ concentrations and there is no correlation between Na+ concentration and L-lysine influx (i.e., L-lysine influx is "Na+ independent"). Therefore, Na+ may have an activating role, resulting in an effect on Vmax, a "velocity effect" (14, 17, 24), but need not necessarily be transported into the vesicles together with the amino acid. Similar observations were made by Mircheff et al. (18) in rabbit renal brush-border vesicles: an inwardly directed Na+ gradient accelerates L-lysine uptake compared with a K+ gradient by a process that is described to be Na+ independent. In the experiments using NaSCN preequilibrated vesicles, L-lysine influx was higher in Lys animals than in control chickens (there was no effect in vesicles preequilibrated with KSCN). Because in these conditions no ionic diffusion potentials are expected and the only gradient is the chemical gradient, the results indicate that Na+ exerts some facilitation on the transport process that is membrane potential independent. It is thus concluded that the effects of L-lysine supplementation can be explained by changes in the already described transport systems rather than the appearance of new transporters. It is also concluded that transport of L-lysine does not appear to absolutely depend on Na+ and that lysine supplementation stimulates the role of Na+ in the activation of the transport process.Adaptive regulation. The intestinal absorption of nutrients is regulated, among other factors, by dietary substrate levels. According to the adaptive regulation hypothesis (9-11) a nutrient carrier is repressed when its biosynthetic costs exceed the benefit it provides and vice versa. For example, the transport of D-glucose and D-fructose, which are nonessential nontoxic nutrients that can be used as a source of energy, is upregulated by luminal sugars. However, essential amino acids such as L-lysine may induce a different pattern, depending on their degree of toxicity and whether their transport is shared with other amino acids.
Karasov et al. (12) fed mice with a diet supplemented with 6% L-lysine, and they observed that dietary lysine induces a 19% stimulation of normalized L-lysine uptake; because experiments were done using high substrate external concentrations, the increase was ascribed to an effect on the number of carriers. Growth rates and body weight were, however, lower than animals fed nonessential amino acids. No significant effects of L-lysine were observed by Karasov et al. (12) on intestinal morphometric parameters. This is consistent with preliminary results of Amat et al. (1) showing no changes in nominal surface area in the small intestine of Lys-fed chickens. From calculations based on the kinetic constants of Table 3 it has been estimated that chickens fed the Lys diet show about a 50% increase in total influx with Na+ present in the lumen. At high luminal lysine concentrations (e.g., 10 mmol/l) increased transport is due to the 20-fold increase in b0,+ activity and to the 36% increase across y+-like system; however, because the y+ system is a high-capacity transport mechanism, its contribution to the increased amount of L-lysine taken up is much higher (64%) than that of b0,+-like system (contributes 36%). At low substrate concentrations (1-10 µmol/l), however, the contribution of system b0,+ to increased uptake is higher (88%) than the contribution of system y+ (only 12%). The high-capacity y+-like system behaves as predicted by the adaptive regulation hypothesis; it shows no variations in Km and a significant increase in Vmax. It is a typical induction in the activity of carriers in response to the increased luminal lysine concentration. The low-capacity system identified as b0,+ shows increased Vmax and Km for the substrate, although the L-lysine transport rates are increased at both low (2-3 fold) and high (30-fold) substrate concentrations. The change in Km would not support the hypothesis, but it must be considered that the Km values of the b0,+ system may be overestimated in our experimental conditions (26). In conclusion, dietary lysine supplementation results in an increased L-lysine transport capacity by the chicken intestine as a result of both upregulation of existing carriers and an increased Na+-sensitivity in the activation process.Perspectives
The transport of cationic amino acids across biological membranes can be mediated by a number of carriers, namely y+, y+L, b0,+, and B0,+. In the present paper and in a previous one (26) we have confirmed the presence in the intestine of a b0,+ (but not B0,+) activity, and our results strongly indicate that an activity resembling y+ is functionally present in the luminal brush-border membrane of the chicken.It is interesting to note that the intestinal systems involved in L-lysine uptake interact with neutral amino acids and also that Na+ has an activating role in transport apparently without being cotransported with the substrate, and both features need further investigation. It will also be interesting to see whether dietary supplementation of the chickens with L-methionine, an essential amino acid with some degree of toxicity, can downregulate L-methionine uptake by the intestine of this animal species, as predicted by the adaptive regulation hypothesis.
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ACKNOWLEDGEMENTS |
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We thank Drs. Rosa Devés and Manuel Palacín for their comments and valuable discussions. We also thank Irta-Mas Bové (Generalitat de Catalunya, Reus, Tarragona) for the formulation, preparation, and chemical analyses of diets used.
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FOOTNOTES |
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This work was supported by Grant ALI96-910 from the Dirección General de Investigación Científica y Técnica, Spain. J.F. Soriano-García was a recipient of a Formació d'Investigadors Grant from Generalitat de Catalunya. M. Torras-Llort was a research fellow of the Recerca i Docència program, Universitat de Barcelona.
Part of this work was presented at the 14th Meeting of the European Intestinal Transport Group and was published in abstract form (27).
Address for reprint requests: Prof. M. Moretó, Unitat de Fisiologia, Facultat de Farmàcia, Av. Joan XXIII s/n, E-08028 Barcelona, Spain.
Received 12 February 1997; accepted in final form 11 September 1997.
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REFERENCES |
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Top
Abstract
Introduction
Methods
Results
Discussion
References
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1.
Amat, C., H. Claramunt, and M. Moretó.
Adaptation of
L-lysine uptake by the chicken
jejunum to dietary
L-lysine. Int. Joint
Meet. Physiol.: Soc. Española de Ciencias Fisiológicas and
Am. Physiol. Soc. Málaga, 1997.
2.
Bertran, J.,
A. Werner,
G. Stange,
D. Markovich,
J. Biber,
X. Testar,
A. Zorzano,
M. Palacín,
and
H. Murer.
Expression of Na+-independent amino acid transport in Xenopus laevis oocytes by injection of rabbit kidney cortex mRNA.
Biochem. J.
281:
717-723,
1992.
3.
Dahlqvist, A.
Assay of intestinal disaccharidases.
Scand. J. Clin. Lab. Invest.
44:
169-172,
1984[Medline].
4.
Del Castillo, J. R.,
and
J. W. L. Robinson.
The simultaneous preparation of basolateral and brush-border membrane vesicles from guinea-pig intestinal epithelium and the determination of the orientation of the basolateral vesicles.
Biochim. Biophys. Acta
688:
45-56,
1982[Medline].
5.
Devés, R.,
S. Angelo,
and
P. Chávez.
N-ethylmaleimide discriminates between two L-lysine transport systems in human erythrocytes.
J. Physiol. (Lond.)
468:
753-766,
1993
6.
Devés, R.,
P. Chávez,
and
C. A. R. Boyd.
Identification of a new transport system (y+L) in human erythrocytes that recognizes lysine and leucine with high affinity.
J. Physiol. (Lond.)
454:
491-501,
1992
7.
Diamond, J. M.,
and
W. H. Karasov.
Effect of dietary carbohydrate on monosaccharide uptake by mouse small intestine in vitro.
J. Physiol. (Lond.)
349:
419-440,
1984
8.
D'Mello, J. P. F.
Responses of growing poultry to amino acids.
In: Amino Acids in Farm Animal Nutrition, edited by J. P. F. D'Mello. Wallingford, UK: Cab International, 1994, p. 205-243.
9.
Ferraris, R. P.
Regulation of intestinal nutrient transport.
In: Physiology of the Gastrointestinal Tract, edited by L. R. Johnson. New York: Raven, 1994, p. 1821-1843.
10.
Ferraris, R. P.,
and
J. M. Diamond.
Specific regulation of intestinal nutrient transporters by their dietary substrates.
Annu. Rev. Physiol.
51:
125-141,
1989[Medline].
11.
Karasov, W. H.
Test of the adaptive modulation hypothesis for dietary control of intestinal nutrient transport.
Am. J. Physiol.
263 (Regulatory Integrative Comp. Physiol. 32):
R496-R502,
1992
12.
Karasov, W. H.,
D. H. Solberg,
and
J. M. Diamond.
Dependence of intestinal amino acid uptake on dietary protein or amino acid levels.
Am. J. Physiol.
252 (Gastrointest. Liver Physiol. 15):
G614-G625,
1987
13.
Kessler, M.,
O. Acuto,
C. Storelli,
M. Murer,
M. Müller,
and
G. Semenza.
A modified procedure for the rapid preparation of efficiently transporting vesicles from small intestinal brush border membranes. Their use in investigating some properties of D-glucose and choline transport systems.
Biochim. Biophys. Acta
506:
136-154,
1978[Medline].
14.
Kimmich, G. A.
Intestinal absorption of sugar.
In: Physiology of the Gastrointestinal Tract, edited by L. R. Johnson. New York: Raven, 1981, p. 1035-1061.
15.
Leclerq, B.,
A. H. Chagneau,
T. Couchard,
and
J. Khoury.
Comparative responses of genetically lean and fat chickens to lysine, arginine and non-essential amino acid supply. I. Growth and body composition.
Br. Poult. Sci.
35:
687-696,
1994[Medline].
16.
Lipstein, B. S.,
S. Bornstein,
and
I. Bartov.
The replacement of some soybean meal by the first-limiting amino acids in partial broiler diets. 3. Effects of protein concentrations and amino acid supplementation in broiler finisher diets on fat deposition in the carcass.
Br. Poult. Sci.
16:
627-635,
1975.
17.
Maenz, D. D.,
and
J. F. Patience.
L-Threonine transport in pig jejunal brush border membrane vesicles.
J. Biol. Chem.
267:
22079-22086,
1992
18.
Mircheff, A. K.,
I. Kippen,
B. Hirayama,
and
E. M. Wright.
Delineation of sodium-stimulated amino acid transport pathways in rabbit kidney brush border vesicles.
J. Membr. Biol.
64:
113-122,
1982[Medline].
19.
Morris, T. R.,
and
S. Abebe.
Effects of arginine on chicks' responses to dietary lysine.
Br. Poult. Sci.
31:
261-266,
1990[Medline].
20.
Morris, T. R.,
K. Al-Azzawai,
R. M. Gous,
and
G. L. Simpson.
Effects of protein concentration on responses to dietary lysine by chicks.
Br. Poult. Sci.
28:
185-195,
1987[Medline].
21.
Murer, H.,
J. Biber,
P. Gmaj,
and
B. Stieger.
Cellular mechanisms in epithelial transport: advantages and disadvantages of studies with vesicles.
Mol. Physiol.
6:
55-82,
1984.
22.
National Research Council.
Nutrient Requirements of Poultry (9th ed.). Washington, DC: National Academy Press, 1994.
23.
Soriano-García, J. F.,
M. Torras-Llort,
J. M. Planas,
R. Ferrer,
and
M. Moretó.
Na+-independent transport of L-methionine in brush-border membrane vesicles of chicken jejunum (Abstract).
Physiol. Res.
45:
12,
1996.
24.
Stein, W. D.
Coupling of flows of substrates: antiporters and symporters.
In: Channels, Carriers and Pumps. An Introduction to Membrane Transport. San Diego, CA: Academic, 1990, p. 173-219.
25.
Thwaites, D. T.,
D. Markovich,
H. Murer,
and
N. L. Simmons.
Na+-independent lysine transport in human intestinal Caco-2 cells.
J. Membr. Biol.
151:
215-224,
1996[Medline].
26.
Torras-Llort, M.,
R. Ferrer,
J. F. Soriano-García,
and
M. Moretó.
L-Lysine transport in chicken jejunal brush border membrane vesicles.
J. Membr. Biol.
152:
183-193,
1996[Medline].
27.
Torras-Llort, M.,
J. F. Soriano-García,
J. M. Planas,
R. Ferrer,
and
M. Moretó.
Adaptation of L-lysine transport via system b0,+ to an L-lysine-enriched diet (Abstract).
Physiol. Res.
45:
13,
1996.
28.
Van Winkle, L. J.,
H. N. Christensen,
and
A. L. Campione.
Na+-dependent transport of basic, zwitterionic and bicyclic amino acids by a broad-scope system in mouse blastocysts.
J. Biol. Chem.
260:
12118-12123,
1985
29.
Wolffram, S.,
H. Giering,
and
E. Scharrer.
Na+-gradient dependence of basic amino acid transport into rat intestinal brush border membrane vesicles.
Comp. Biochem. Physiol. A Physiol.
78:
475-480,
1984.
30.
Wolffram, S.,
and
E. Scharrer.
Effect of feeding a high protein diet on amino acid uptake into rat intestinal brush border membrane vesicles.
Pflügers Arch.
400:
34-39,
1984[Medline].
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, control diet; 
, Lys
diet). Membranes were prepared in 300 mmol/l mannitol and 20 mmol/l
HEPES-Tris, pH 7.4. Incubation medium contained 100 mmol/l salt, 100 mmol/l mannitol, 20 mmol/l HEPES-Tris, pH 7.4, and 100 µmol/l
L-lysine (6.6 µmol/l
L-[14C]lysine).
Each value represents mean ± SE of 3-5 membrane preparations.
Only SE that exceed size of symbol are shown.
