Kinetic evidence for separate systems in transport of D- and L-methionine by rat small intestine
The kinetics of D- and L-methionine uptake by rings of everted intestine in vitro are consistent with a saturable Michaelis-Menten component plus a linear, diffusional one. All the data could be fit with a diffusion constant, which was essentially the same, independent of whether it was estimated by iteration or by using the extracellular marker, (/sup 3/H), inulin. Similar results were obtained from in vivo perfusion experiments, except that the diffusional term was negligible. D-(3,4-/sup 14/C)Methionine was found to inhibit L-methionine uptake by intestinal rings according to fully noncompetitive kinetics. Another set of experiments with jejunal brush-border membrane vesicles showed that D-methionine uptake is dependent on a Na/sup +/ gradient and is significantly inhibited by L-(/sup 35/S) methionine and L-prolie, but not by ..beta..-alanine and ..cap alpha..-methylaminoisobutyric acid. The results indicate that, in rat jejunum, D-methionine is taken up through a Na/sup +/-dependent pathway distinct from the neutral amino acid (L-methionine) carrier and from the amino acid (L-proline,..cap alpha..-methylaminoisobutyric acid, ..beta..-alanine) carrier.
- Research Organization:
- Centre National de la Recherche Scientifique, Marseille, France
- OSTI ID:
- 5356329
- Journal Information:
- Am. J. Physiol.; (United States), Vol. 252:3
- Country of Publication:
- United States
- Language:
- English
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LABELLED COMPOUNDS
MEMBRANE TRANSPORT
METHIONINE
BIOCHEMICAL REACTION KINETICS
DOSE-RESPONSE RELATIONSHIPS
IN VITRO
INHIBITION
RATS
SMALL INTESTINE
SULFUR 35
TIME DEPENDENCE
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARBOXYLIC ACIDS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DRUGS
EVEN-ODD NUCLEI
GASTROINTESTINAL TRACT
INTESTINES
ISOTOPES
KINETICS
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
RADIOISOTOPES
REACTION KINETICS
RODENTS
SULFUR ISOTOPES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques