Relationship between blood, liver and brain pyridoxal phosphate and pyridoxamine phosphate concentrations in mice (original) (raw)
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The Journal of nutrition, 1989
A decrease in plasma pyridoxal-5'-phosphate (PLP) occurs during pregnancy in humans and experimental animals for reasons that are not known. To determine if mice also develop decreased plasma PLP concentrations during pregnancy, and if plasma PLP levels in pregnancy reflect tissue levels of PLP and pyridoxamine-5'-phosphate (PMP), we measured PLP concentrations in plasma, erythrocytes and whole blood, and liver and brain PLP and PMP in control and pregnant mice. Mice were fed a nonpurified diet containing 8.13 mg pyridoxine-HCl/kg. The PLP analyses were performed in our newly developed apotryptophanase method in which the substrate S-benzyl-L-cysteine is hydrolyzed to benzyl mercaptan, reacted with Ellman's reagent and measured spectrophotometrically. During pregnancy, plasma PLP levels decreased 50% below control levels, but erythrocyte and whole blood PLP levels increased 2.9- and 1.6-fold, respectively. Liver PLP and PMP decreased 25%, in parallel with plasma PLP, but...
Background: Low chronic vitamin B-6 status can occur in a subset of women who use oral contraceptives (OCs) with uncertain metabolic consequences. An insufficiency of cellular pyridoxal 5#-phosphate (PLP), which is the coenzyme form of vitamin B-6, may impair many metabolic processes including one-carbon and tryptophan metabolism. Objective: We investigated the effects of vitamin B-6 supplementation on the in vivo kinetics of one-carbon metabolism and the concentration of one-carbon and tryptophan metabolites in vitamin B-6–deficient OC users. Design: A primed, constant infusion of [ 13 C 5 ]methionine, [3-13 C]serine, and [ 2 H 3 ]leucine was performed on 10 OC users (20–40 y old; plasma PLP concentrations ,30 nmol/L) before and after 28 d of supplementation with 10 mg pyridoxine hydrochloric acid/d. In vivo fluxes of total homocysteine remethylation, the remethylation of homocysteine from serine, and rates of homocysteine and cystathionine production were assessed. Targeted metabolite profiling was performed, and data were analyzed by using orthogonal partial least-squares– discriminant analysis and paired t tests adjusted for multiple testing. Results: Pyridoxine supplementation increased the mean 6 SD plasma PLP concentration from 25.8 6 3.6 to 143 6 58 nmol/L (P , 0.001) and decreased the leucine concentration from 103 6 17 to 90 6 20 nmol/L (P = 0.007) and glycine concentration from 317 6 63 to 267 6 58 nmol/L (P = 0.03). Supplementation did not affect in vivo rates of homocysteine remethylation or the appearance of homocysteine and cystathionine. A multivariate analysis showed a clear overall effect on metabolite profiles resulting from supplemen-tation. Leucine, glycine, choline, cysteine, glutathione, trimethylamine N-oxide, and the ratios glycine:serine, 3-hydroxykynurenine:kynure-nine, 3-hydroxykynurenine:3-hydroxyanthranilic acid, and 3-hydroxy-kynurenine:anthranilic acid were significant discriminating variables. Conclusions: Consistent with previous vitamin B-6–restriction studies , fluxes of one-carbon metabolic processes exhibited little or no change after supplementation in low–vitamin B-6 subjects. In contrast, changes in the metabolic profiles after supplementation indicated perturbations in metabolism, suggesting functional vitamin B-6 deficiency.
The American journal of clinical nutrition, 2008
No large-scale, population-based study has considered the descriptive epidemiology of vitamin B-6 status with use of plasma pyridoxal 5'-phosphate (PLP), the indicator of vitamin B-6 adequacy used to set the current Recommended Dietary Allowance, which is < or = 2 mg/d for all subgroups. We sought to examine the epidemiology of vitamin B-6 status in the US population. In > 6000 participants aged > or = 1 y in the National Health and Nutrition Examination Survey (2003-2004), we considered relations between plasma PLP and various subject characteristics and examined trends in plasma PLP and homocysteine with vitamin B-6 intake, both overall and in selected subgroups. In males, plasma PLP decreased with age after adolescence only in nonusers of supplemental vitamin B-6. Regardless of supplement use, plasma PLP concentrations of women of childbearing age were significantly lower than those of comparably aged men, and most oral contraceptive users had plasma PLP < 20 nmol...
Clinica Chimica Acta, 1999
We describe a procedure for the measurement of pyridoxal 59-phosphate and of 4-pyridoxic acid in human plasma samples. It is based on the conversion of pyridoxal 59-phosphate to 4-pyridoxic acid 59-phosphate by cyanide in alkaline medium, followed by a high pressure liquid chromatographic separation, with fluorescence detection at acid pH. The assay is robust, sensitive, linear over a wide range, reproducible, and simple to perform. Samples stored at 2 808C are stable. Satisfactory agreement was obtained with results from the tyrosine decarboxylase-based assay for pyridoxal 59-phosphate, in two other laboratories. Plasma samples from a National Survey of older British people were analyzed, and reference intervals for plasma pyridoxal 59-phosphate intervals were derived. From the lower 2.5 percentile of the reference group, taken as the lower cut-off of the normal range, ca. 20% of elderly men and 11% of elderly women in the UK showed evidence of biochemical deficiency.
2019
In many studies, vitamin B6 is given as the sum of the pyridoxal (PL), pyridoxine (PN) and pyridoxamine (PM) forms. In a limited number of studies, PL, PN and PM forms of vitamin B6 in animal origin foods were reported. Since the bioavailability of PL, PN and PM forms of vitamin B6 are different; knowing the amounts of these forms in foods is important in terms of healthy nutrition. In this study, the PL, PN and PM forms in a total of 38 animal-based foods were determined by high performance liquid chromatography (HPLC). PL and PM were found predominantly in fish, meats and chicken samples. Within these, the highest amount of vitamin B6 were found in golden grey mullet by 616.3 μg/100g, in veal fillet at 376.1 μg/100g and in chicken breast by 329.5 μg /100g, respectively. The PL form in total vitamin B6 ranged in fish between 32.5 and 53.1%, in meats between 15.6 and 48.9%, and in chicken samples between 59.9 and 69.8%. It was also found that milk and milk products contain low amoun...
Journal of Nutritional Science and Vitaminology, 2010
A method for determining all of the six natural vitamin B 6 compounds and pyridoxine--glucoside in urine from humans consuming their usual diet was developed. These compounds were specifically converted with 5 enzymes into a high fluorescent 4-pyridoxolactone which was supersensitively determined by an isocratic HPLC. All of the compounds in urine from humans consuming their usual diets were for the first time determined together. The preparation procedure for urine samples was easy without HClhydrolysis, and the enzyme reactions took only 2 or 3 h. It required only 5 L of the urine sample for analysis of one of the compounds. Urine samples from five young Japanese males consuming their usual diet contained pyridoxal, pyridoxamine, and pyridoxine--glucoside but not pyridoxine or phosphoester forms. The contents of 4-pyridoxic acid and pyridoxal correlate well with a correlation coefficient of 0.98. On the other hand, the content of pyridoxamine did not correlate with that of 4-pyridoxic acid.
Journal of Pharmaceutical Sciences, 1993
0 An HPLC method for determining total pyridoxal from plasma was developed for a relative bioavailability comparison of two oral vitamin 6 , (pyridoxine HCI) preparations. After cleavage of the pyridoxal-5-phosphate with the acid phosphatase enzyme, the total pyridoxal was determined by HPLC. Pyridoxal was separated on a reversed-phase column, post-column derivatized to pyridoxalsemicarbazide, and then detected by fluorescence and quantitated. The limit of detection was 2 ng/mL and interday variation (3 days) over the whole concentration range (13-215 ng/mL spiked) was <4.1%. In the relative bioavailability study, 16 human subjects were put on a low vitamin 6 , diet for a period of 3 days. On the 2nd and 3rd days, 14 blood samples were taken per subject at the same times each day. The drug was administered on the 3rd day. Total endogenous pyridoxal detected on the 2nd day varied in plasma between 13 and 17 ng/mL. Pharmacokinetic parameters corrected for background are reported for two vitamin 6 , (40 mg) preparations. Briefly, the pharmacokinetic results for the Ratiopharm preparation compared with the Hoffmann-La Roche preparation are, respectively: AUC, , , 369.2 and 352.6 ng h/mL; AUC, , , 1638.2 and 1662.3 ng. h/mL; net C,,, 193.0 and 197.1 ng/mL; k, , 1.25 and 1.44 h; and relative bioavailability, 97.9% (Westlake, 8&112%).
Transport and metabolism of pyridoxal and pyridoxal phosphate in the small intestine of the rat
Journal of Nutrition
The vascularly perfused small intestine of the rat was utilized to study the absorption and metabolism of pyridoxamine (PM) and pyridoxamine-5'-phosphate (PMP), independent of other tissues in cluding erythrocytes. [:'H]PM or [3H]PMP was administered intralumenally with or without the addition of unlabeled PM, or PMP or inorganic phosphate. The percentage absorption of PM was 17.1 to 19.7% in 10 minutes and was unaffected by dosages from 0.02 to 200 /¿mole. The isotope from [3H]PMP at a physiological level (0.02 /¿mole)was absorbed at the same rate as that from [3H]PM, and the distribution of the 3H remaining in the lumen and in the intestinal tissue and perfusate indicated that hydrolytic removal of the phosphate was occurring extensively in the gut. The spectrum of labeled compounds isolated from the lumen, the perfusate and the mucosa clearly indicated that PMP, unhydrolyzed, can be absorbed slowly and converted to a number of vitamin B-6 forms in the intestinal mucosa. However, the results support the view that under normal physi ological conditions the majority of dietary PMP is hydrolyzed to PM which seems to be absorbed by passive diffusion and transported to other organs and tissues via the blood stream.
The Journal of Nutrition, 1973
Male Wistar rats were fed diets containing 10% corn oil and supple mented with or deficient in pyridoxine. One pyridoxine-supplemented group was pairfed with the deficient group. After 12 weeks, each group was divided into two subgroups which were fed diets containing 10% hydrogenated coconut oil and supple mented or deficient in pyridoxine for 20 weeks. Blood samples were taken from the tail vein at 4-week intervals and erythrocyte fatty acids analyzed. Lack of pyridoxine for the entire experiment resulted in the most rapid loss of erythrocyte arachidonate and incorporation of oleic and eicosatrienoic acids. At the end of the experiment, there was less arachidonic acid and more oleic and eicosatrienoic acids in erythrocyte lipids from this group of rats than from any other group. Animals receiving vitamin B« throughout the experiment exhibited the smallest changes in tissue fatty acid composition. The effects of changing the B6 status of the diet in the second phase of the experiment were less well defined. Loss of arachidonic acid from the erythrocyte after imposition of the EFA-deficient diet was more rapid if pyridoxine deficiency accompanied the EFA de ficiency rather than preceding it. However, the final concentrations of arachidonic acid did not differ in these two groups.
Alcohol, 1990
Pyridoxal Y-phosphate andpyridoxamine Y-phosphate concentrations in blood and tissues of mice fed ethanol-containing liquid diets. ALCOHOL 7(1) 61-68, 1990.-The effects of chronic ethanol administration on vitamin B-6 metabolism were studied in female Long-Sleep (LS) and Short-Sleep (SS) mice. Animals were fed an ethanol containing liquid diet (AIN-76) for four weeks. Concentration of ethanol in the diet increased from 10 to 25% ethanol-derived calories (EDC) during weeks 1-3 and was maintained at 30% EDC for 1 additional week. We measured concentrations of pyridoxal 5'-phosphate (PLP) in plasma, erythrocytes and whole blood, and liver and brain PLP and pyridoxamine 5'-phosphate (PMP) in ethanol-fed and pair-fed control mice. Chronic ethanol administration significantly increased PMP and total (PLP + PMP) levels in the liver of SS mice. In LS mice ethanol feeding significantly decreased PMP and total (PLP + PMP) levels in the brain, but these values were still within normal limits. These results suggest that both control and ethanol-containing liquid diets are nutritionally adequate with respect to vitamin B-6, and that chronic ethanol administration does not adversely affect vitamin B-6 metabolism in adult mice.