Improved high-performance liquid chromatographic determination of thiamine and its phosphate esters in animal tissues

Synthesis, physico-chemical properties and effect of adenosine thiamine triphosphate on vitamin B1 metabolism in the liver of alloxan diabetic rats

BACKGROUND

Adenosine thiamine triphosphate (AThTP) is a nucleotide discovered in bacteria and some other living organisms more than a decade ago. No biochemical function for AThTP has been established yet, however, experimental data available indicate its possible involvement in metabolic regulation or cell signaling. Metabolism of AThTP in mammals, as well as the feasibility of its pharmacological application, is essentially unstudied.

METHODS

Preparative low-pressure chromatography was employed to purify chemically synthesized AThTP with its further analysis by mass spectrometry, HPLC, UV and fluorescence spectroscopy. Enzyme activity assays along with HPLC were used to examine the effects of AThTP and thiamine on vitamin B₁ metabolism in the liver of alloxan-induced diabetic rats.

RESULTS

An improved procedure for AThTP synthesis and purification is elaborated. Solution stability, optical spectral properties and the molar absorption coefficient for AThTP were determined. The levels of thiamine compounds were found to be increased in the liver of diabetic rats. Neither AThTP nor thiamine treatment affected hepatic vitamin B₁ metabolism. Fasting blood glucose concentration was also unchangeable after AThTP or thiamine administration.

GENERAL SIGNIFICANCE

Contrast to the widespread view about thiamine deficiency in diabetes, our results clearly shows an adaptive increase in the level of B₁ vitamers in the liver of alloxan diabetic rats with no further rising after AThTP or thiamine treatment at a moderate dose. Neither AThTP nor thiamine is effective in glycaemic control. These findings are to be considered in future studies dealing with thiamine or its analogues application to correct metabolic disturbances in diabetes.

Nutritional Factors That Affect the Formation of 5-Aminolevulinic Acid, a Key Intermediate of Heme Biosynthesis

5-Aminolevulinic acid (ALA) is a key intermediate of heme biosynthesis, which is an essential component of the respiratory chain. Therefore, nutrients that affect ALA biosynthesis eventually affect ATP production, which is the basis of mitochondrial function. Although the effects of various non-nutrient components that affect ALA after biosynthesis have been reported, there are few reports on the effects of dietary amino acids/protein on ALA formation and the effects of dietary vitamins that are involved in amino acid metabolism. In mitochondria, ALA is synthesized from succinyl-CoA and glycine by the pyridoxal phosphate-dependent enzyme ALA synthase [EC 2.3.1.37]. In this study, the effects of dietary amino acids/protein and vitamins on the amount of ALA synthesized were investigated using mice, rats, and cultured cells. Amounts of ALA in plasma and urine, and porphyrins in plasma increased with increasing protein intake. Vitamin B₁ insufficiency did not affect ALA synthesis. Vitamin B₆ insufficiency increased the amount of ALA synthesized, while niacin deficiency markedly reduced ALA synthesis. Thus, for heme synthesis, an essential biological substance for life, the amounts of amino acids, as well as the pathways metabolizing amino acids to glycine and succinyl-CoA are very important. Specifically, it is important that niacin is associated with the formation of glycine and succinyl-CoA from amino acids.

Effects of B-Group Vitamin Administration on Daily Change in Urine 2-Oxo Acids in Young Japanese Women

B-group vitamins are required in amino acid catabolism, and recent findings suggest that urine 2-oxo acids, catabolites of amino acid, could be functional biomarkers indicating the nutritional status of B-group vitamins. To clarify the relationship between B-group vitamins and urine 2-oxo acids, we investigated the effects of B-group vitamin administration on daily changes in urinary amounts of 2-oxo acids in humans. Twenty-nine young Japanese women collected 24-h urine samples for 8 d, and took B-group vitamins for 7 d beginning on the second day of urine collection. The participants were divided into three groups on the basis of the amounts of total branched-chain 2-oxo acids, 2-oxoglutaric acid, 2-oxoadipic acid, and pyruvic acid excreted in urine. In the upper tertile, but not the middle and lower tertiles, each urine 2-oxo acid decreased from the first day of vitamin administration, and completely decreased to a normal level on the second day of administration. These results indicate that administration of B-group vitamins immediately affects 2-oxo acid metabolism in some young Japanese women. Thus, urinary 2-oxo acids could be useful and functional biomarkers for B-group vitamin status.

A Suitable Diet for Recovery from Starvation Is a High-Fat Diet, but Not a High-Protein Diet, in Rats

The present study aims to determine the most suitable dietary balance of energy-producing nutrients for recovery from starvation. Rats were fed their standard high- carbohydrate diet (HCD, carbohydrate energy : protein energy : fat energy=71 : 18 : 11) for 7 d and then deprived of food for 3 d (short-term starvation) or 8 d (long-term starvation). The starved rats were then fed the HCD, a high-protein diet (HPD, 31 : 57 : 12), or a high-fat diet (HFD, 34 : 14 : 52) for 8 d. Rats had ad libitum access to drinking water throughout the experimental period, including the starvation period. The reference group was allowed free access to the HCD throughout the experimental period. Characteristically, increased drinking, increased urea nitrogen in the plasma and urine, and hypertrophy of the kidneys, were observed in the HPD group. Furthermore, the recovery of plasma glucose level was insufficient in this group. Therefore, administration of a HPD was contraindicated in recovery from starvation. The recovery of body weight after starvation was excellent in the HFD group. No effect on the metabolism of B-group vitamins involved in energy metabolism was found with the administration of any diet. The effects of HCD and HFD administration on recovery from starvation were investigated in further detail. No adverse effects were observed on the tissue to body weight mass ratios or biochemical parameters in blood in the HFD group. From the above findings, it is hypothesized that a HFD is most suitable for quickly reversing the influence of starvation.

High-dose thiamine prevents brain lesions and prolongs survival of Slc19a3-deficient mice

SLC19A3 deficiency, also called thiamine metabolism dysfunction syndrome-2 (THMD2; OMIM 607483), is an autosomal recessive neurodegenerative disorder caused by mutations in SLC19A3, the gene encoding thiamine transporter 2. To investigate the molecular mechanisms of neurodegeneration in SLC19A3 deficiency and whether administration of high-dose thiamine prevents neurodegeneration, we generated homozygous Slc19a3 E314Q knock-in (KI) mice harboring the mutation corresponding to the human SLC19A3 E320Q, which is associated with the severe form of THMD2. Homozygous KI mice and previously reported homozygous Slc19a3 knock-out (KO) mice fed a thiamine-restricted diet (thiamine: 0.60 mg/100 g food) died within 30 and 12 days, respectively, with dramatically decreased thiamine concentration in the blood and brain, acute neurodegeneration, and astrogliosis in the submedial nucleus of the thalamus and ventral anterior-lateral complex of the thalamus. These findings may bear some features of thiamine-deficient mice generated by pyrithiamine injection and a thiamine-deficient diet, suggesting that the primary cause of THMD2 could be thiamine pyrophosphate (TPP) deficiency. Next, we analyzed the therapeutic effects of high-dose thiamine treatment. When the diet was reverted to a conventional diet (thiamine: 1.71 mg/100 g food) after thiamine restriction, all homozygous KO mice died. In contrast, when the diet was changed to a high-thiamine diet (thiamine: 8.50 mg/100 g food) after thiamine restriction, more than half of homozygous KO mice survived, without progression of brain lesions. Unexpectedly, when the high-thiamine diet of recovered mice was reverted to a conventional diet, some homozygous KO mice died. These results showed that acute neurodegeneration caused by thiamine deficiency is preventable in most parts, and prompt high-dose thiamine administration is critical for the treatment of THMD2. However, reduction of thiamine should be performed carefully to prevent recurrence after recovery of the disease.

Effects of Mild and Severe Vitamin B1 Deficiencies on the Meiotic Maturation of Mice Oocytes

We investigated the effects of vitamin B₁ deficiency on the meiosis maturation of oocytes. Female Crl:CD1 (ICR) mice were fed a 20% casein diet (control group) or a vitamin B₁–free diet (test group). The vitamin B₁ concentration in ovary was approximately 30% lower in the test group than in the control group. Oocyte meiosis was not affected by vitamin B₁ deficiency when the deficiency was not accompanied by body weight loss. On the contrary, frequency of abnormal oocyte was increased by vitamin B₁ deficiency when deficiency was accompanied by body weight loss (referred to as severe vitamin B₁ deficiency; frequency of abnormal oocyte, 13.8% vs 43.7%, P = .0071). The frequency of abnormal oocytes was decreased by refeeding of a vitamin B₁–containing diet (13.9% vs 22.9%, P = .503). These results suggest that severe vitamin B₁ deficiency inhibited meiotic maturation of oocytes but did not damage immature oocytes.

Urinary excretion ratio of xanthurenic acid/kynurenic acid as a functional biomarker of niacin nutritional status

The present study was conducted to survey functional biomarkers for evaluation of niacin nutritional status. Over 500 enzymes require niacin as a coenzyme. Of these, we chose the tryptophan degradation pathway. To create niacin-deficient animals, quinolinic acid phosphoribosyltransferase-knock out mice were used in the present study because wild type mice can synthesize nicotinamide from tryptophan. When the mice were made niacin-deficient, the urinary excretion of xanthurenic acid (XA) was extremely low compared with control mice; however, it increased according to the recovery of niacin nutritional status. The urinary excretion of kynurenic acid (KA) was the reverse of XA. Kynurenine 3-monooxygenase, which needs NADPH, was thought to be suppressed by niacin deficiency. Thus, we calculated the urinary excretion ratio of XA:KA as a functional biomarker of niacin nutrition. The ratio increased according to recovering niacin nutritional status. Low values equate with low niacin nutritional status.

Urinary Branched-Chain 2-Oxo Acids as a Biomarker for Function of B-Group Vitamins in Humans

To find a functional biomarker of B-group vitamins, we collected 24-h urine samples from young Japanese women who lived in the community (n=29) to measure branched-chain 2-oxo acids such as 2-oxo-3-methylbutanoic acid, 2-oxo-3-methylpentanoic acid, and 2-oxo-4-methylpentanoic acid because B-group vitamins are involved in the catabolism of branched-chain amino acids. The relationships between each pair of the three urinary 2-oxo acids were very high (2-oxo-3-methylbutanoic acid and 2-oxo-3-methylpentanoic acid, p<0.001; 2-oxo-3-methylbutanoic acid and 2-oxo-4-methylpentanoic acid, p<0.001; 2-oxo-3-methylpentanoic acid and 2-oxo-4-methylpentanoic acid, p<0.001). The participants were divided into three groups using the upper (n=10), middle (n=9), and lower tertiles (n=10) based on the urinary excretion amounts of the sum of the three branched-chain 2-oxo acids. The administration of capsules containing the daily necessary amounts of B-group vitamins led to a decrease in the urinary excretion of the sum of the three types of branched-chain 2-oxo acids in participants belonging to the upper tertile. A similar phenomenon was observed in the middle tertile, but not in the lower tertile. Intakes of B-group vitamins and the urinary excretion amounts of B-group vitamins were not observed to be significantly different among the upper, middle, and lower tertiles. These results indicate that some young Japanese women need much higher levels of B-group vitamins than the Dietary Reference Intakes for Japanese. Thus, urinary branched-chain 2-oxo acids are useful functional biomarkers for B-group vitamins in humans.

High-performance liquid chromatographic method for profiling 2-oxo acids in urine and its application in evaluating vitamin status in rats

B-group vitamins are involved in the catabolism of 2-oxo acids. To identify the functional biomarkers of B-group vitamins, we developed a high-performance liquid chromatographic method for profiling 2-oxo acids in urine and applied this method to urine samples from rats deficient in vitamins B1 and B6 and pantothenic acid. 2-Oxo acids were reacted with 1,2-diamino-4,5-methylenebenzene to produce fluorescent derivatives, which were then separated using a TSKgel ODS-80Ts column with 30 mmol/L of KH2PO4 (pH 3.0):acetonitrile (7:3) at a flow rate of 1.0 mL/min. Vitamin B1 deficiency increased urinary levels of all 2-oxo acids, while vitamin B6 deficiency only increased levels of sum of 2-oxaloacetic acid and pyruvic acid, and pantothenic acid deficiency only increased levels of 2-oxoisovaleric acid. Profiles of 2-oxo acids in urine samples might be a non-invasive way of clarifying the functional biomarker of B-group vitamins.

Tissue vitamin concentrations are maintained constant by changing the urinary excretion rate of vitamins in rats' restricted food intake

We previously reported that mild food restriction induces a reduction in tryptophan-nicotinamide conversion, which helps to explain why death secondary to pellagra is pandemic during the hungry season. In this study, we investigated the levels of B-group vitamins in the liver, kidney, blood, and urine in rats that underwent gradual restriction of food intake (80, 60, 40, and 20% restriction vs. ad libitum food intake). No significant differences in the B-group vitamin concentrations (mol/g tissue) in the liver and kidney were observed at any level of food restriction. However, the urine excretion rates exhibited some characteristic phenomena that differed by vitamin. These results show that the tissue concentrations of B-group vitamins were kept constant by changing the urinary elimination rates of vitamins under various levels of food restriction. Only vitamin B12 was the only (exception).

Relationship Between Urinary Concentrations of Nine Water-soluble Vitamins and their Vitamin Intakes in Japanese Adult Males

Excess water-soluble vitamins are thought to be eliminated in the urine. We have reported a strong relationship between water-soluble vitamin intake and urinary excretion in females. The relationship, however, is not well understood in males. In the present experiment, 10 Japanese male subjects were given a standard Japanese diet for the first week. The subjects remained on the same diet, and a synthesized water-soluble vitamin mixture containing one time the Dietary Reference Intakes (DRIs) for Japanese was given for the second week, three times the DRIs for the third week, and six times the DRIs for the fourth week. Twenty-four-hour urine samples were collected each week. Urinary excretion levels for seven of the nine water-soluble vitamin levels, excluding vitamin B₁₂ and folate, increased linearly and sharply in a dose-dependent manner. These results suggest that measuring urinary water-soluble vitamins can be good nutritional markers for assessing vitamin intakes in humans.

Thiamine triphosphate synthesis in rat brain occurs in mitochondria and is coupled to the respiratory chain

In animals, thiamine deficiency leads to specific brain lesions, generally attributed to decreased levels of thiamine diphosphate, an essential cofactor in brain energy metabolism. However, another far less abundant derivative, thiamine triphosphate (ThTP), may also have a neuronal function. Here, we show that in the rat brain, ThTP is essentially present and synthesized in mitochondria. In mitochondrial preparations from brain (but not liver), ThTP can be produced from thiamine diphosphate and P(i). This endergonic process is coupled to the oxidation of succinate or NADH through the respiratory chain but cannot be energized by ATP hydrolysis. ThTP synthesis is strongly inhibited by respiratory chain inhibitors, such as myxothiazol and inhibitors of the H(+) channel of F(0)F(1)-ATPase. It is also impaired by disruption of the mitochondria or by depolarization of the inner membrane (by protonophores or valinomycin), indicating that a proton-motive force (Deltap) is required. Collapsing Deltap after ThTP synthesis causes its rapid disappearance, suggesting that both synthesis and hydrolysis are catalyzed by a reversible H(+)-translocating ThTP synthase. The synthesized ThTP can be released from mitochondria in the presence of external P(i). However, ThTP probably does not accumulate in the cytoplasm in vivo, because it is not detected in the cytosolic fraction obtained from a brain homogenate. Our results show for the first time that a high energy triphosphate compound other than ATP can be produced by a chemiosmotic type of mechanism. This might shed a new light on our understanding of the mechanisms of thiamine deficiency-induced brain lesions.

Products of the colonic microbiota mediate the effects of diet on colon cancer risk

It is estimated that most colon cancers can be attributed to dietary causes. We have hypothesized that diet influences the health of the colonic mucosa through interaction with the microbiota and that it is the milieu interior that regulates mucosal proliferation and therefore cancer risk. To validate this further, we compared colonic contents from healthy 50- to 65-y-old people from populations with high and low risk, specifically low risk Native Africans (cancer incidence <1:100,000; n = 17), high risk African Americans (risk 65:100,000; n = 17), and Caucasian Americans (risk 50:100,000; n = 18). Americans typically consume a high-animal protein and -fat diet, whereas Africans consume a staple diet of maize meal, rich in resistant starch and low in animal products. Following overnight fasting, rapid colonic evacuation was performed with 2 L polyethylene glycol. Total colonic evacuants were analyzed for SCFA, vitamins, nitrogen, and minerals. Total SCFA and butyrate were significantly higher in Native Africans than in both American groups. Colonic folate and biotin content, measured by Lactobacillus rhamnoses and Lactobacillus plantarum ATCC 8014 bioassay, respectively, exceeded normal daily dietary intakes. Compared with Africans, calcium and iron contents were significantly higher in Caucasian Americans and zinc content was significantly higher in African Americans, but nitrogen content did not differ among the 3 groups. In conclusion, the results support our hypothesis that the microbiota mediates the effect diet has on colon cancer risk by their generation of butyrate, folate, and biotin, molecules known to play a key role in the regulation of epithelial proliferation.

Thiaminylated adenine nucleotides. Chemical synthesis, structural characterization and natural occurrence

Thiamine and its three phosphorylated derivatives (mono-, di- and triphosphate) occur naturally in most cells. Recently, we reported the presence of a fourth thiamine derivative, adenosine thiamine triphosphate, produced in Escherichia coli in response to carbon starvation. Here, we show that the chemical synthesis of adenosine thiamine triphosphate leads to another new compound, adenosine thiamine diphosphate, as a side product. The structure of both compounds was confirmed by MS analysis and 1H-, 13C- and 31P-NMR, and some of their chemical properties were determined. Our results show an upfield shifting of the C-2 proton of the thiazolium ring in adenosine thiamine derivatives compared with conventional thiamine phosphate derivatives. This modification of the electronic environment of the C-2 proton might be explained by a through-space interaction with the adenosine moiety, suggesting U-shaped folding of adenosine thiamine derivatives. Such a structure in which the C-2 proton is embedded in a closed conformation can be located using molecular modeling as an energy minimum. In E. coli, adenosine thiamine triphosphate may account for 15% of the total thiamine under energy stress. It is less abundant in eukaryotic organisms, but is consistently found in mammalian tissues and some cell lines. Using HPLC, we show for the first time that adenosine thiamine diphosphate may also occur in small amounts in E. coli and in vertebrate liver. The discovery of two natural thiamine adenine compounds further highlights the complexity and diversity of thiamine biochemistry, which is not restricted to the cofactor role of thiamine diphosphate.

Thiamine-like fibers in the monkey brain: an immunocytochemical study

The distribution of thiamine-immunoreactive structures was studied in the brain of the monkey using an indirect immunoperoxidase technique. Fibers containing thiamine, but no thiamine-immunoreactive cell bodies, were found. The highest density of fibers containing thiamine was observed in the pulvinar nucleus and in the region extending from the pulvinar nucleus to the caudate nucleus. In the mesencephalon, immunoreactive fibers containing thiamine were only found at rostral level close to the medial lemniscus (at the mesencephalic-diencephalic junction). In the thalamus, the distribution of thiamine-immunoreactive structures was more widespread. Thus, immunoreactive fibers were found in nuclei close to the midline (centrum medianum/parafascicular complex), in the ventrolateral thalamus (medial geniculate nucleus, inferior pulvinar nucleus), and in the dorsolateral thalamus (lateral posterior nucleus, pulvinar nucleus). Finally, in the anterior commissure and in the cerebral cortex a low density immunoreactive fibers was visualized. Thus, in the brainstem, no immunoreactive structures were visualized in the medulla oblongata, pons, or in the medial-caudal mesencephalon, and no immunoreactive fibers were observed in the cerebellum, hypothalamus and in the basal ganglia. The present report describes the first visualization and the morphological characteristics (thick, smooth and short, medium or long in length) of the thiamine-immunoreactive fibers in the primate central nervous system using an antiserum directed against this vitamin. The distribution of thiamine-immunoreactive structures in the monkey brain suggests that this vitamin could be involved in several physiological mechanisms.

Determination of thiamine and its phosphate esters in rat tissues analyzed as thiochromes on a RP-amide C16 column

A new reversed-phase chromatographic method is described for the separation and quantification of thiamine (T), thiamine monophosphate (TMP) and diphosphate (TDP) in rat tissues. Sample extraction with perchloric acid (HClO(4)) was found more suitable than extraction with trichloroacetic acid (TCA), as regards convenience and background fluorescence. Derivatization of thiamine vitamers to thiochromes was optimized and complete separation of TDP and TMP thiochromes was obtained on a RP-amide C16 column in isocratic elution, with T thiochrome eluting in less than 10 min. The precision and the accuracy of the HPLC procedure were assessed: ranging from 0.5 to 7.7% for intra-day and from 2.0 to 9.4% for inter-day precision, a recovery average of 101% was determined (range 90-111%). Mean values of recovery for TDP, TMP or T were 91, 96 and 90% for liver extracts, respectively. Analysis of vitamers in tissues of rat submitted to 8 days thiamin deficiency, followed by a 14 days repletion, showed a significant reduction of TPP after 8 days of depletion in liver (-67%), brains (-50%), kidneys (-60%), followed by a complete recovery upon repletion.

Determination of thiamine by high-performance liquid chromatography

High-performance liquid chromatographic methods for the determination of thiamine (vitamin B1) in foodstuffs or biological tissues and fluids are outlined and discussed. The methods are often similar and interchangeable, sample extraction and clean up procedures being the major difference. Most of the methods use either ultraviolet or fluorescence detection. Fluorescence detection requires either precolumn or postcolumn oxidation of thiamine to thiochrome. A number of methods are recommended and problems with standardization are emphasized.

Determination of thiamin and its phosphate esters in cultured neurons and astrocytes using an ion-pair reversed-phase high-performance liquid chromatographic method

A sensitive method, based on fluorescence detection, for the determination of thiamin derivatives after precolumn derivatization is described. The separation is achieved on a PRP-1 column using ion-pair reversed-phase HPLC. This method is especially well adapted to the detection of thiamin triphosphate in complex mixtures such as tissue extracts. The detection limit for TTP is 50 fmol. The contents of thiamin derivatives were determined in primary cultures of rat cerebellar granule neurons and cerebral astrocytes. The amount of TTP is about five times higher in neurons than in astrocytes. Thus in rat brain TTP seems to be essentially associated with neurons and the intracellular concentration is estimated to be about 0.2 microM. Our results suggest the existence, in nerve cells, of specific regulatory mechanisms not related to the blood-brain barrier and responsible for the maintenance of thiamin homeostasis in brain.

Application of high-performance liquid chromatography to the study of thiamine metabolism and in particular thiamine triphosphatase

Thiamine triphosphate can be found in most tissues at very low levels, but its role is unknown. Organs and muscles that generate electrical impulses are particularly rich in this compound. This paper describes a thiamine triphosphatase from the electrical organ of Electrophorus electricus. The activity of this enzyme, as measured by a high-performance liquid chromatographic method, is closely anion-regulated. Furthermore, thiamine triphosphate increases chloride uptake in membrane vesicles prepared from rat brain. Our results suggest that this compound could play an important role in the regulation of chloride permeability.

Concomitant determination of thiamin and its phosphate esters in human blood and serum by high-performance liquid chromatography

A high-performance liquid chromatographic method for the simultaneous determination of thiamin and thiamin phosphate esters in human blood or serum has been developed. The eluent consists of acetonitrile and phosphate buffer, in the ratios 90:10 (v/v) for the elution of thiamine and 60:40 (v/v) for the phosphate esters. The four compounds are eluted within 15 min. The detection limit is 13-16 fmol. Between-assay variation is 5-11%. Samples of whole blood and serum from 30 healthy adults were analysed. The following reference values were obtained for 15 females 15 males (nM, mean +/- S.D.). In serum: thiamin, 10.9 +/- 2.9/16.9 +/- 3.3; thiamin monophosphate, 8.3 +/- 1.5/3.7 +/- 1.5. In whole blood: thiamin, 29.6 +/- 10.0/33.4 +/- 10.4; thiamin monophosphate, 9.7 +/- 2.3/10.9 +/- 5.1; thiamin diphosphate, 121 +/- 29.6/165 +/- 40.4.

Postnatal development of thiamine metabolism in rat skeletal muscle

1. The activities of 2-oxoglutarate dehydrogenase, transketolase, thiamine pyrophosphokinase and thiamine triphosphatase and the concentrations of thiamine phosphates were almost the same between rat extensor digitorum longus and soleus muscles at 2 weeks of age. 2. These enzyme activities changed after 3 weeks of age in a different way depending on the muscle phenotype. 3. Thiamine diphosphate level and the activity of 2-oxoglutarate dehydrogenase increased only in soleus muscle and thiamine triphosphate level increased only in extensor digitorum longus during development.

Membrane-associated thiamine triphosphatase in rat skeletal muscle

1. Thiamine triphosphatase activity in particulate fraction, but not in soluble, of rat skeletal muscle was stimulated by several anions. 2. The stimulative effect of anions was dependent on pH of reaction medium and was reversible. 3. The activities of ATPase in rat muscle particulate preparation and thiamine triphosphatase in the brain were inhibited by the anions.

Postnatal development of thiamine metabolism in rat brain

The activities of thiamine diphosphatase (TDPase), thiamine triphosphatase (TTPase), and thiamine pyrophosphokinase and the contents of thiamine and its phosphate esters were determined in rat brain cortex, cerebellum, and liver from birth to adulthood. Microsomal TTPase activity in the cerebral cortex and cerebellum increased from birth to 3 weeks, whereas that in the liver did not change during postnatal development. Microsomal TDPase activity in the cerebral cortex showed a transient increase at 1-2 weeks, but that in the cerebellum did not change during development. In contrast to the activity of the brain enzyme, that of liver microsomal TDPase increased stepwise after birth. Thiamine pyrophosphokinase activity in the cerebellum increased from birth to 3 weeks and then decreased, whereas that in the cerebral cortex and liver showed less change during development. TDP and thiamine monophosphate (TMP) levels increased after birth and plateaued at 3 weeks whereas TTP and thiamine levels showed little change during development in the cerebral cortex and cerebellum. The contents of thiamine and its phosphate esters in the liver showed more complicated changes during development. It is concluded that thiamine metabolism in the brain changes during postnatal development in a different way from that in the liver and that the development of thiamine metabolism differs among brain regions.

Difference in thiamine metabolism between extensor digitorum longus and soleus muscles

1. Thiamine diphosphate level was higher in soleus muscle than in extensor digitorum longus muscle in various animals, whereas thiamine triphosphate level was less in the former muscle than in the latter except for mouse. 2. 2-Oxoglutarate dehydrogenase, transketolase and thiamine pyrophosphokinase activities were higher in soleus muscle than in extensor digitorum longus in rat and guinea pig. 3. The differences between rat two muscle phenotypes in thiamine diphosphate, but not thiamine triphosphate, level and the thiamine-related enzyme activities disappeared after denervation. 4. Tenotomy had little effect on thiamine phosphate levels and the thiamine-related enzyme activities in rat skeletal muscles.

Tissue difference in cellular localization of thiamine phosphate esters

1. Thiamine phosphate levels were determined in the soluble and particulate fractions of various rat tissues. 2. There was marked tissue difference in the cellular localization of thiamine phosphates. 3. Brain thiamine triphosphate was localized only in the particulate fraction, whereas skeletal muscle thiamine triphosphate was in the soluble fraction as a protein-unbound form.