Intestinal transport of l-tryptophan in vitro: inhibition by high concentrations

1960 ◽  
Vol 199 (6) ◽  
pp. 1033-1036 ◽  
Author(s):  
Richard P. Spencer ◽  
A. H. Samiy
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Aromatic Amino Acids ◽  
Intestinal Transport ◽  
Serosal Side ◽  
Mutual Inhibition ◽  
High Concentrations ◽  
Two Sides ◽  
Bathing Fluid

At a concentration of 5 x 10–3 m, everted hamster intestinal sacs showed net transport of l-tryptophan from the mucosal to the serosal side, when the concentration was initially equal on the two sides. Thus, l-tryptophan is not an exception to the generalization that such intestinal preparations transport monoamino-monocarboxylic amino acids against a concentration gradient. High concentrations of l-tryptophan inhibit such transport. This may account for previous failure by others to observe l-tryptophan transport against a gradient at an initial concentration of 20 x 10–3 m. Transport of l-tryptophan was greater by sacs from the middle of the small intestine than by those from the ends (this has been previously reported for l-phenylalanine and l-tyrosine). On the basis of this observation and those of mutual inhibition of transport, it is likely that the four aromatic amino acids share at least one common step in their intestinal absorption. Segments of hamster small intestine have been shown to accumulate l-tryptophan, developing a concentration greater than that of the bathing fluid.

Chloride-dependent intestinal transport of imino and beta-amino acids in the guinea pig and rat

1994 ◽  
Vol 266 (3) ◽  
pp. R997-R1007 ◽  
Author(s):  
L. K. Munck ◽  
B. G. Munck
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Guinea Pig ◽  
Intestinal Transport ◽  
Isobutyric Acid ◽  
Acid Activation ◽  
Beta Alanine ◽  
Imino Acid ◽  
Proximal Small Intestine

The present study extends the observations of chloride-dependent intestinal amino acid carriers to the guinea pig and the rat using the technique of in vitro influx across the brush-border membrane of intact epithelium. Transport rates of D-glucose and L-amino acids are lowest in guinea pig proximal small intestine and are constant from midjejunum through distal ileum, except for leucine. The guinea pig possesses a sodium- and chloride-dependent, high-affinity, very low-capacity carrier of beta-amino acids for which taurine and beta-alanine compete and for which the Na(+)-taurine activation stoichiometry is 2.1 +/- 0.3:1. The imino acid carrier of the guinea pig is also chloride dependent with a Na(+)-Cl(-)-2-methylamino-isobutyric acid activation stoichiometry of 1.8 +/- 0.1:0.7 +/- 0.3:1. In contrast, the rat imino acid carrier is chloride independent and transport rates vary insignificantly along the small intestine. The rat taurine carrier has its maximal transport rate in midjejunum. It is chloride dependent but does not transport beta-alanine.

Active transport of C14-d-glucose by turtle small intestine

1961 ◽  
Vol 201 (2) ◽  
pp. 295-297 ◽  
Author(s):  
Sister Alice Marie Fox
Keyword(s):  
Small Intestine ◽  
Active Transport ◽  
Intestinal Transport ◽  
Intestinal Wall ◽  
Chrysemys Picta ◽  
Tissue Analysis ◽  
Serosal Side ◽  
Concentration Difference ◽  
Apparent Concentration

An in vitro preparation was used to demonstrate that C14-d-glucose is taken up at the mucosal surface of turtle small intestine at 30 C. Movement of the sugar across the intestinal tissues and its release into the serosal fluid against an apparent concentration difference was shown. The source of the sugar entering the medium on the serosal side appeared to be, in part, the glucose taken up from the mucosal fluid, and, in part, some stored carbohydrate. Tissue analysis indicated the presence of a glycogenlike polysaccharide in the intestinal wall of both active and cold-torpid turtles. It was concluded that, during intestinal transport in Chrysemys picta, some of the glucose absorbed is converted to endogenous carbohydrate, or metabolized, and some is translocated.

Intestinal transport of amino acids studied in vitro with l-[131I]monoiodotyrosine

1960 ◽  
Vol 41 (2) ◽  
pp. 271-282 ◽  
Author(s):  
Daniel Nathans ◽  
Donald F. Tapley ◽  
Joan E. Ross
Keyword(s):  
Amino Acids ◽  
Intestinal Transport

In vivo and in vitro Absorption of Amino Acids and Dipeptides in the Small Intestine of Uremic Rats

Nephron ◽  
1982 ◽  
Vol 31 (3) ◽  
pp. 273-276 ◽  
Author(s):  
G. Sterner ◽  
T. Lindberg ◽  
T. Denneberg
Keyword(s):  
Amino Acids ◽  
Small Intestine

scholarly journals Amino acids and carbohydrates absorption by Na+-dependent transporters in the pyloric ceca of Hoplias malabaricus (Erythrinidae)

2001 ◽  
Vol 31 (5) ◽  
pp. 793-797 ◽  
Author(s):  
Vania Lucia Pimentel Vieira ◽  
Bernardo Baldisserotto
Keyword(s):  
Amino Acids ◽  
Optimal Growth ◽  
Serosal Side ◽  
Carbohydrate Absorption ◽  
Hoplias Malabaricus ◽  
Main Site ◽  
Adequate Diet ◽  
Mucosal Side ◽  
Pyloric Ceca

Information about amino acids and carbohydrate absorption in fish is important to formulate an adequate diet to obtain optimal growth. Therefore, the objective of this study was to investigate if Na+-dependent transporters are involved on the absorption of glycine, L-glutamine, L-leucine, L-lysine, L-proline, L-alanine, and the carbohydrates fructose and glucose in the pyloric ceca of Hoplias malabaricus. The pyloric ceca were mounted in a system of continuous perfusion "in vitro". Amino acids and carbohydrates were placed on the mucosal side at concentrations of 10, 20, and 40mM. The serosal side of the pyloric ceca was positive in relation to the mucosal side. The addition of glycine, L-glutamine, L-leucine, L-lysine, L-proline (all tested concentrations), and glucose (at concentrations of 20 and 40mM) increased the positivity of the serosal side, indicating the presence of Na+-dependent transporters in the absorption of these substances. L-alanine and fructose did not change the positivity of the serosal side. The pyloric ceca seem to be the main site of nutrient absorption in the digestive tract of H. malabaricus.

In Vitro Absorption of Amino Acids by the Small Intestine of Sheep

1976 ◽  
Vol 42 (1) ◽  
pp. 201-207 ◽  
Author(s):  
W. A. Phillips ◽  
K. E. Webb ◽  
J. P. Fontenot
Keyword(s):  
Amino Acids ◽  
Small Intestine

In Vitro adsorption Spectrum of Plasma Amino Acids by Coated Charcoal Hemoperfusion

1983 ◽  
Vol 6 (5) ◽  
pp. 267-270 ◽  
Author(s):  
Z.Q. Shi ◽  
T.M.S. Chang
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Hepatic Coma ◽  
Aromatic Amino Acids ◽  
Molar Ratio ◽  
Adsorption Experiment ◽  
Preferential Adsorption ◽  
Branched Chain ◽  
Charcoal Hemoperfusion

In order to clarify wether coated charcoal hemoperfusion is capable of normalizing amino acid disturbances in hepatic coma, in vitro adsorption and in vitro hemoperfusion studies were carried out. We have found that collodion-coated activated charcoal beads preferentially removed much more aromatic acids (AAA) than branched chain amino acids (BCAA). In the in vitro adsorption experiment with 50 μM amino acid standards aqueous solution, 99% of AAAs were removed by charcoal while only 50 to 81% of BCAAs were removed. As the concentration of amino acids in solution was doubled from μM to 100 μM, BCAA removal was halved while about 90% of AAA was still being removed. In vitro hemoperfusion with heparinized blood from hepatic failure rats, the clearance and the removal of AAAs were significantly greater than those of BCAAs. Consequently, the molar ratio of BCAA over AAA was markedly improved from the initial 1.09 to 3.87 after 60 min of hemoperfusion. Thus, we have demonstrated the preferential adsorption of aromatic amino acids by collodion-coated charcoal beads. The correction of BCAA/AAA molar ratio is also demonstrated.

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