Transport of neutral, dibasic and N-methyl-substituted amino acids by rat intestine

Larsen, P. Reed; Ross, J. E.; Tapley, Donald F.

doi:10.1016/0926-6577(64)90100-7

Cited by 34 publications

(28 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The apparent Kt and V max found here for Lmethionine and glucose were similar to those reported previously in chicks (Lerner and Taylor, 1967;Shehata et al, 1981) and rats (Larsen et al, 1964). Determination of the apparent Kt in this study indicated that this parameter changed little with increasing age for both glucose and methionine.…”

Section: Discussionsupporting

confidence: 88%

Uptake Capacity In Vitro for Glucose and Methionine and In Situ for Oleic Acid in the Proximal Small Intestine of Posthatch Chicks

Noy

Sklan

1996

Poultry Science

View full text Add to dashboard Cite

The uptake capacity of the duodenum and jejunum was determined in vitro for glucose and methionine using 14C-inulin as an unabsorbed reference substance in posthatch chicks. Fatty acid uptake in situ was also determined in the duodenum. Methionine uptake capacity increased in both duodenum and jejunum between hatch and 7 d and was constant between 7 and 14 d. Calculation of apparent Michaelis constant (Kt) for both substrates indicated little change with age and thus the amount of carrier in the intestine may be increasing. Uptake capacity of the duodenum for glucose increased between hatch and 7 d of age but no changes were found between 7 and 14 d. In the jejunum, uptake capacity was constant from hatch to 14 d of age. In situ uptake of oleic acid in the duodenum did not change between hatch and 14 d of age. These results suggest that intestinal uptake capacity changes little after 7 d of age, and thus feed intake may be the major factor controlling nutrient uptake in chicks.

show abstract

Section: Discussionsupporting

confidence: 88%

Uptake Capacity In Vitro for Glucose and Methionine and In Situ for Oleic Acid in the Proximal Small Intestine of Posthatch Chicks

Noy

Sklan

1996

Poultry Science

View full text Add to dashboard Cite

show abstract

“…It is interesting that lysine and arginine are also transported by the same carrier protein (Hidalgo and Borchardt 1990;Larsen et al 1964;Pardridge 1982).…”

Section: Discussionmentioning

confidence: 98%

Double blind placebo control trial of large neutral amino acids in treatment of PKU: Effect on blood phenylalanine

Matalon

Michals‐Matalon

Bhatia

et al. 2007

J of Inher Metab Disea

View full text Add to dashboard Cite

Large neutral amino acids (LNAA) have been used on a limited number of patients with phenylketonuria (PKU) with the purpose of decreasing the influx of phenylalanine (Phe) to the brain. In an open-label study using LNAA, a surprising decline of blood Phe concentration was found in patients with PKU in metabolic treatment centres in Russia, the Ukraine, and the United States. To validate the data obtained from this trial, a short-term double-blind placebo control study was done using LNAA in patients with PKU, with the participation of three additional metabolic centres--Milan, Padua and Rio de Janeiro. The results of the short trial showed significant lowering of blood Phe concentration by an average of 39% from baseline. The data from the double-blind placebo control are encouraging, establishing proof of principle of the role of orally administered LNAA in lowering blood Phe concentrations in patients with PKU. Long-term studies will be needed to validate the acceptability, efficacy and safety of such treatment.

show abstract

“…Lysine and arginine are also transported on the same carrier protein (Hidalgo and Borchardt 1990;Larsen et al 1964;Pardridge 1982). According to the experiments of Hidalgo and Borchardt (1990), using human intestinal-epithelial cells (Caco-2-cells in monolayers with a buffer containing 10 μmol/L Phe), significant inhibition of Phe transport requires 100-fold (1 mmol/L) LNAAs, as dictated by the K m equation for affinity of LNAAs to the GI carrier protein.…”

Section: Discussionmentioning

confidence: 99%

Large neutral amino acids in the treatment of phenylketonuria (PKU)

Matalon

Michals‐Matalon

Bhatia

et al. 2006

J of Inher Metab Disea

View full text Add to dashboard Cite

Large neutral amino acids (LNAAs) have been used on a limited number of patients with phenylketonuria (PKU) with the purpose of decreasing the influx of phenylalanine (Phe) to the brain. In earlier studies on mice with PKU (ENU(2)/ENU(2)), LNAAs were given and a surprising decline in blood Phe concentrations was observed. The formula used in the mouse experiment (PreKUnil) lacked lysine. Therefore, a new formulation of LNAAs (NeoPhe) was developed, introducing changes in the concentration of some amino acids and adding lysine, so that such a mixture could be used in humans. The new formula was found to be effective in reducing blood Phe concentration in mice by about 50% of the elevated levels. Patients with PKU were given LNAAs and blood Phe concentrations were determined in an open-label study. Three centers--in Russia, the Ukraine and the USA--took part in the study. NeoPhe was given at 0.5 g/kg per day in three divided doses to eight subjects with PKU and at 1.0 g/kg per day to three patients, for one week. The NeoPhe resulted in decrease of elevated blood Phe by 50% in both groups. The preliminary data from this study are encouraging and a double blind placebo-controlled trial will be required to show long-term efficacy and tolerance of LNAAs in the treatment of PKU.

show abstract

Transport of neutral, dibasic and N-methyl-substituted amino acids by rat intestine

Cited by 34 publications

References 15 publications

Uptake Capacity In Vitro for Glucose and Methionine and In Situ for Oleic Acid in the Proximal Small Intestine of Posthatch Chicks

Uptake Capacity In Vitro for Glucose and Methionine and In Situ for Oleic Acid in the Proximal Small Intestine of Posthatch Chicks

Double blind placebo control trial of large neutral amino acids in treatment of PKU: Effect on blood phenylalanine

Large neutral amino acids in the treatment of phenylketonuria (PKU)

Contact Info

Product

Resources

About