Portal and Vena Caval Plasma Methionine Concentrations in Young Pigs Administered L-Methionine, N-Acetyl-L-Methionine and N-Acetyl-D-Methionine

Daabees, Tahia T.; Andersen, Dean W.; Zike, Wilbur L.; Filer, L. J.; Stegink, Lewis D.

doi:10.1093/jn/114.9.1541

Cited by 17 publications

(10 citation statements)

References 17 publications

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“…Increases in NAM were not detected at 30 min in either sex, suggesting that NAM was rapidly excreted or further metabolized. Daabees et al (1984) reported similar Met levels in pigs dosed with Met or NAM, consistent with efficient conversion of NAM to Met.…”

Section: Resultssupporting

confidence: 54%

In Vivo Metabolism of l-Methionine in Mice: Evidence for Stereoselective Formation of Methionine-d-Sulfoxide and Quantitation of Other Major Metabolites

Dever¹,

Elfarra²

2006

Drug Metab Dispos

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Flavin-containing monooxygenases (FMOs) are microsomal enzymes that catalyze the NADPH-and O 2 -dependent oxidation of heteroatoms (nitrogen, sulfur, phosphorus) present in the chemical structure of a variety of drugs and xenobiotics. Five functional forms (FMO1-5) have been characterized to date (Ziegler, 2002). In humans, FMO1 is the primary isoform expressed in neonate liver, but a switch occurs shortly after birth to FMO3, the primary isoform expressed in adult human liver (Koukouritaki et al., 2002). In mice, females, but not males, also express FMO3 in the liver (Falls et al., 1995;Ripp et al., 1999b). This sex-specific expression of FMO3 in mice makes them an attractive model for studying the role of FMO3 in human drug metabolism and disease.Our laboratory first identified Met as a substrate for cDNA-expressed rabbit FMO1-3 with K m values of 48.0, 29.9, and 6.5 mM, respectively (Duescher et al., 1994). The V/K values (0.9, 1.7, and 6.1 for FMO1-3, respectively) also suggested that FMO3 was the most efficient Met S-oxidizer of these three FMO isoforms. FMO3 Soxidation of Met was highly stereoselective, forming 8.4 times more methionine-d-sulfoxide (Met-d-O) than methionine-l-sulfoxide (Metl-O), whereas the d:l diastereomeric ratios for FMO1 and FMO2 were 1.5:1 and 0.7:1, respectively; FMO5 S-oxidation of Met was not detected. Recombinant human FMO3 exhibited a K m value of 3.7 mM with a V/K value of 4.6 and resulted in stereoselective formation of (Ripp et al., 1999b). Recombinant human FMO4 S-oxidation of Met exhibited a K m value greater than 10 mM with only 30% of the total sulfoxide formed being Met-d-O (Ripp et al., 1999a). The V/K value for FMO4 was not determined. These data indicated that FMO3 S-oxidation of Met proceeds with the highest affinity and greatest diastereomeric selectivity among FMO1-5.Stereoselective formation of Met-d-O was also detected in rabbit and rat liver microsomes incubated with Met, and exhibited K m and V/K values similar to those of cDNA-expressed FMO3 (Duescher et al., 1994;Krause et al., 1996). The latter results provided evidence for FMO3 being the primary isoform involved in Met S-oxidation in rabbit and rat liver. Additional experiments also provided evidence that FMOs, but not cytochrome P450s, peroxidases, or reactive oxygen species, mediated the Met S-oxidase activity (Krause et al., 1996).

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Section: Resultssupporting

confidence: 54%

In Vivo Metabolism of l-Methionine in Mice: Evidence for Stereoselective Formation of Methionine-d-Sulfoxide and Quantitation of Other Major Metabolites

Dever¹,

Elfarra²

2006

Drug Metab Dispos

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“…NALM fed to adult humans appears to be equivalent to dietary L-methionine (25). Similar findings are reported in adult pigs (27), rats (28), and human infants; the metabolic requirements of the latter for L-methionine and NALM appear to be greater than those of adults (29). In mice, greater body weight gains are achieved with NALM, as well as some other methionine derivatives, than with L-methionine (30).…”

Section: Discussionsupporting

confidence: 69%

Growth inhibition of subcutaneously transplanted hepatomas without cachexia by alteration of the dietary arginine‐methionine balance

Millis

Diya

Reynolds

et al. 1998

Nutrition and Cancer

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Previous studies have shown that alteration of the dietary arginine-methionine balance by use of synthetic L-amino acids inhibits tumor growth of a subcutaneously transplanted Morris hepatoma at the expense of maintaining body weight. However, L-methionine is susceptible to degradation and, therefore, may contribute to a deficiency state. The present studies were performed to determine whether growth of subcutaneous hepatoma transplants is inhibited, and body growth maintained, when rats are fed diets containing L-methionine in replacement of N-acetyl-L-methionine (NALM) for 28 days. Tumor-free and tumor-bearing rats fed a control diet, with amino acids replacing protein, had gains in body weight: 31.3 +/- 1.0 and 19.1 +/- 0.5 g (12% and 7%), respectively. Rats fed six experimental diets, with varying L-arginine-NALM balances, had body weight gains ranging from 18.4 +/- 0.3 to 26.7 +/- 0.9 g (7-10%). Tumor weight of control rats was 10.65 +/- 0.24% of body weight. Diets supplemented with L-arginine in combination with normal and deficient NALM decreased tumor weights by 35% and 38%, respectively, It is concluded that dietary replacement of L-methionine with NALM and supplementation with L-arginine inhibits growth of a subcutaneously transplanted Morris hepatoma in the absence of cachexia.

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“…The amino acid content in hepatic portal venous plasma increases shortly after intrajejunal administration [3], however, such a rapid increase of the l-arginine plasma level may be unusual after oral administration. The functional significance of the effect of l-arginine therefore remains to be elucidated in future studies.…”

Section: Discussionmentioning

confidence: 96%

Effects of l-arginine on spontaneous contraction of the rat portal vein

Shimamura

Zhou

Toba

et al. 2003

Pflugers Arch - Eur J Physiol

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The effects of L-arginine on spontaneous contraction of endothelium-denuded longitudinal preparations of the rat portal vein were studied. L-arginine increased the frequency of spontaneous contraction concentration-dependently between 10 microM and 1 mM. Changes in contraction amplitude and duration were not remarkable. D-arginine had a negligible effect on spontaneous contraction. N(omega)-nitro-L-arginine (1 mM) did not affect spontaneous contraction or the response to L-arginine. Addition of N(G)-monomethyl-L-arginine (1 mM), l-lysine (1 mM) or N-ethymaleimide (0.1 mM) increased the frequency of spontaneous contractions and inhibited the effect of L-arginine. Glibenclamide (10 microM) did not affect spontaneous contraction or the response to L-arginine. Spontaneous increase in concentration of intracellular Ca2+, estimated as the ratio of Fura-PE3 fluorescence occurred synchronously with spontaneous contraction. Spontaneous increase in concentration of intracellular Ca2+ occurred more frequently in the presence of L-arginine (1 mM). L-arginine (1 mM) also increased the number of action potential bursts/min in the longitudinal smooth muscle layer. L-arginine (1 mM) also depolarized cell membranes. This study indicates that L-arginine increases the frequency of spontaneous contraction of longitudinal muscle in the rat portal vein by membrane depolarization through mechanisms that do not involve nitric oxide or the inhibition of ATP-sensitive K+ channels.

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Portal and Vena Caval Plasma Methionine Concentrations in Young Pigs Administered L-Methionine, N-Acetyl-L-Methionine and N-Acetyl-D-Methionine

Cited by 17 publications

References 17 publications

In Vivo Metabolism of l-Methionine in Mice: Evidence for Stereoselective Formation of Methionine-d-Sulfoxide and Quantitation of Other Major Metabolites

In Vivo Metabolism of l-Methionine in Mice: Evidence for Stereoselective Formation of Methionine-d-Sulfoxide and Quantitation of Other Major Metabolites

Growth inhibition of subcutaneously transplanted hepatomas without cachexia by alteration of the dietary arginine‐methionine balance

Effects of l-arginine on spontaneous contraction of the rat portal vein

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