Metabolism of γ-hydroxybutyrate in perfused rat livers

2012 ◽  
Vol 444 (2) ◽  
pp. 333-341 ◽  
Author(s):  
Guo-Fang Zhang ◽  
Sushabhan Sadhukhan ◽  
Rafael A. Ibarra ◽  
Stephanie M. Lauden ◽  
Chia-Ying Chuang ◽  
...  
Keyword(s):  
Date Rape ◽  
Succinic Semialdehyde ◽  
Acetyl Coa ◽  
Parallel Processes ◽  
Multiple Processes ◽  
Isotopomer Analysis ◽  
Pathway Discovery ◽  
Date Rape Drug ◽  
Rat Livers ◽  
Mass Isotopomer

GHB (γ-hydroxybutyrate) is both a neurotransmitter and a drug of abuse (date-rape drug). We investigated the catabolism of this compound in perfused rat livers. Using a combination of metabolomics and mass isotopomer analysis, we showed that GHB is metabolized by multiple processes, in addition to its previously reported metabolism in the citric acid cycle via oxidation to succinate. A substrate cycle operates between GHB and γ-aminobutyrate via succinic semialdehyde. Also, GHB undergoes (i) β-oxidation to glycolyl-CoA+acetyl-CoA, (ii) two parallel processes which remove C-1 or C-4 of GHB and form 3-hydroxypropionate from C-2+C-3+C-4 or from C-1+C-2+C-3 of GHB, and (iii) degradation to acetyl-CoA via 4-phosphobutyryl-CoA. The present study illustrates the potential of the combination of metabolomics and mass isotopomer analysis for pathway discovery.

Rates of Gluconeogenesis (GNG) in Rat Livers Perfused with [U- 13 C 3 ]lactate and [U- 13 C]pyruvate: Estimating Isotope Dilution by Mass Isotopomer Analysis

1994 ◽  
Vol 27 (1) ◽  
pp. 375-376
Author(s):  
C. Des Rosiers ◽  
L. Di Donato ◽  
B. Comte ◽  
A. Laplante ◽  
C. Marcoux ◽  
...  
Keyword(s):  
Isotope Dilution ◽  
Isotopomer Analysis ◽  
Rat Livers ◽  
Mass Isotopomer

scholarly journals Metabolomics and Mass Isotopomer Analysis as a Strategy for Pathway Discovery: Pyrrolyl and Cyclopentenyl Derivatives of the Pro-Drug of Abuse, Levulinate

2012 ◽  
Vol 26 (2) ◽  
pp. 213-220 ◽  
Author(s):  
Stephanie R. Harris ◽  
Guo-Fang Zhang ◽  
Sushabhan Sadhukhan ◽  
Hua Wang ◽  
Chuan Shi ◽  
...  
Keyword(s):  
Drug Of Abuse ◽  
Isotopomer Analysis ◽  
Pathway Discovery ◽  
Derivatives Of ◽  
Mass Isotopomer

Azo Dye-based Optical Probe for the Detection toward Mimic Molecule of Date Rape Drug

2021 ◽  
pp. 106237
Author(s):  
Jiwon Ryu ◽  
Ramalingam Manivannan ◽  
Young-A Son
Keyword(s):  
Azo Dye ◽  
Date Rape ◽  
Optical Probe ◽  
Date Rape Drug

Comparison of N-methyl-2-pyrrolidone (NMP) and the “date rape” drug GHB: behavioral toxicology in the mouse model

2021 ◽  
Author(s):  
Raffaella Arfè ◽  
Sabrine Bilel ◽  
Micaela Tirri ◽  
Paolo Frisoni ◽  
Giovanni Serpelloni ◽  
...  
Keyword(s):  
Mouse Model ◽  
Date Rape ◽  
Behavioral Toxicology ◽  
Date Rape Drug

Mass isotopomer study of the nonoxidative pathways of the pentose cycle with [1,2-13C2]glucose

1998 ◽  
Vol 274 (5) ◽  
pp. E843-E851 ◽  
Author(s):  
Wai-Nang Paul Lee ◽  
Laszlo G. Boros ◽  
Joaquim Puigjaner ◽  
Sara Bassilian ◽  
Shu Lim ◽  
...  
Keyword(s):  
Pentose Phosphate ◽  
Gas Chromatography Mass Spectrometry ◽  
Hep G2 ◽  
Tracer Method ◽  
Human Hepatoma Cells ◽  
Glucose Flux ◽  
Isotopomer Analysis ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Mass Isotopomer

We present a single-tracer method for the study of the pentose phosphate pathway (PPP) using [1,2-13C2]glucose and mass isotopomer analysis. The metabolism of [1,2-13C2]glucose by the glucose-6-phosphate dehydrogenase, transketolase (TK), and transaldolase (TA) reactions results in unique pentose and lactate isotopomers with either one or two13C substitutions. The distribution of these isotopomers was used to estimate parameters of the PPP using the model of Katz and Rognstad (J. Katz and R. Rognstad. Biochemistry 6: 2227–2247, 1967). Mass and position isotopomers of ribose, and lactate and palmitate (products from triose phosphate) from human hepatoma cells (Hep G2) incubated with 30% enriched [1,2-13C2]glucose were determined using gas chromatography-mass spectrometry. After 24–72 h incubation, 1.9% of lactate molecules in the medium contained one 13C substitution ( m 1) and 10% contained two 13C substitutions ( m 2). A similar m 1-to- m 2ratio was found in palmitate as expected. Pentose cycle (PC) activity determined from incubation with [1,2-13C2]glucose was 5.73 ± 0.52% of the glucose flux, which was identical to the value of PC (5.55 ± 0.73%) determined by separate incubations with [1-13C] and [6-13C]glucose.13C was found to be distributed in four ribose isotopomers ([1-13C]-, [5-13C]-, [1,2-13C2]-, and [4,5-13C2]ribose). The observed ribose isotopomer distribution was best matched with that provided from simulation by substituting 0.032 for TK and 0.85 for TA activity relative to glucose uptake into the model of Katz and Rognstad. The use of [1,2-13C2]glucose not only permits the determination of PC but also allows estimation of relative rates through the TK and TA reactions.

13C isotopomer model for estimation of anaplerotic substrate oxidation via acetyl-CoA

1996 ◽  
Vol 271 (4) ◽  
pp. E788-E799 ◽  
Author(s):  
F. M. Jeffrey ◽  
C. J. Storey ◽  
A. D. Sherry ◽  
C. R. Malloy
Keyword(s):  
Biochemical Analysis ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acetyl Coa ◽  
Acid Cycle ◽  
Propionate Metabolism ◽  
13C Nuclear Magnetic Resonance ◽  
Isotopomer Analysis ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Anaplerotic Pathway

A previous model using 13C nuclear magnetic resonance isotopomer analysis provided for direct measurement of the oxidation of 13C-enriched substrates in the tricarboxylic acid cycle and/or their entry via anaplerotic pathways. This model did not allow for recycling of labeled metabolites from tricarboxylic acid cycle intermediates into the acetyl-CoA pool. An extension of this model is now presented that incorporates carbon flow from oxaloacetate or malate to acetyl-CoA. This model was examined using propionate metabolism in the heart, in which previous observations indicated that all of the propionate consumed was oxidized to CO2 and water. Application of the new isotopomer model shows that 2 mM [3-13C]propionate entered the tricarboxylic acid cycle as succinyl-CoA (an anaplerotic pathway) at a rate equal to 52% of tricarboxylic acid cycle turnover and that all of this carbon entered the acetyl-CoA pool and was oxidized. This was verified using standard biochemical analysis; from the rate (mumol.min-1.g dry wt-1) of propionate uptake (4.0 +/- 0.7), the estimated oxygen consumption (24.8 +/- 5) matched that experimentally determined (24.4 +/- 3).

Use of mass isotopomer distributions in secreted lipids to sample lipogenic acetyl-CoA pool in vivo in humans

1991 ◽  
Vol 261 (4) ◽  
pp. E479-E486 ◽  
Author(s):  
M. K. Hellerstein ◽  
C. Kletke ◽  
S. Kaempfer ◽  
K. Wu ◽  
C. H. Shackleton
Keyword(s):  
Mass Spectrometry ◽  
De Novo ◽  
Density Lipoprotein ◽  
Gas Chromatography Mass Spectrometry ◽  
Invasive Technique ◽  
Acetyl Coa ◽  
Precursor Pool ◽  
Chromatography Mass Spectrometry ◽  
Mass Isotopomer

Measurement of hepatic fatty acid (FA) and cholesterol synthesis has been limited by lack of access to the precursor pool, cytosolic acetyl-CoA. We present a method for inferring the enrichment of the true hepatic lipogenic precursor pool in humans using the frequency distribution of mass isotopomers within enriched circulating polymers of acetyl-CoA [very low-density lipoprotein (VLDL)-palmitate, VLDL-stearate]. Human subjects were infused intravenously (n = 16) with [1-13C]- or [2-13C]acetate. Oral sulfamethoxazole (SMX) was administered concurrently, and the acetylated conjugate (SMX acetate) was used to estimate independently the hepatic cytosolic acetyl-CoA enrichment. Isotopomer frequencies in VLDL-FA were determined by gas chromatography-mass spectrometry, whereas high-performance liquid chromatography-mass spectrometry was used to measure enrichments in SMX acetate. Based on the excess M2/excess M1 ratio in VLDL-FA, calculated acetyl-CoA enrichments were 5.59 +/- 0.33 molar percent excess (MPE), whereas SMX acetate enrichments were 5.38 +/- 0.31 MPE (the 2 methods were not significantly different). Mass isotopomer-calculated and SMX acetate-measured estimates of acetyl-CoA enrichments correlated very closely in individual subjects (r2 = 0.93; P less than 0.0001). De novo hepatic lipogenesis can be measured using isotopomer-calculated precursor enrichments compared with measured incorporation in specific isotopomers of VLDL-FA. In summary, excess isotopomer frequencies in secreted lipids provide a non-invasive technique for estimating hepatic cytosolic acetyl-CoA enrichments in humans in vivo and correlate closely with enrichments observed using the xenobiotic probe technique. Isotopomeric distributions represent a new strategy for accurate measurement of macromolecule synthesis that may be applicable to other classes of molecules besides lipids.

Pattern of substrate utilization in vascular smooth muscle using 13C isotopomer analysis of glutamate

1998 ◽  
Vol 275 (6) ◽  
pp. H2227-H2235 ◽  
Author(s):  
Tara M. Allen ◽  
Christopher D. Hardin
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Acetyl Coa ◽  
Contractile State ◽  
The Tca Cycle ◽  
Direct Measurements ◽  
Isotopomer Analysis ◽  
13C Isotopomer Analysis

Although vascular smooth muscle (VSM) derives the majority of its energy from oxidative phosphorylation, controversy exists concerning which substrates are utilized by the tricarboxylic acid (TCA) cycle. We used 13C isotopomer analysis of glutamate to directly measure the entry of exogenous [13C]glucose and acetate and unlabeled endogenous sources into the TCA cycle via acetyl-CoA. Hog carotid artery segments denuded of endothelium were superfused with 5 mM [1-13C]glucose and 0–5 mM [1,2-13C]acetate at 37°C for 3–12 h. We found that both resting and contracting VSM preferentially utilize [1,2-13C]acetate compared with [1-13C]glucose and unlabeled substrates. The entry of glucose into the TCA cycle (30–60% of total entry via acetyl-CoA) exhibited little change despite alterations in contractile state or acetate concentrations ranging from 0 to 5 mM. We conclude that glucose and nonglucose substrates are important oxidative substrates for resting and contracting VSM. These are the first direct measurements of relative substrate entry into the TCA cycle of VSM during activation and may provide a useful method to measure alterations in VSM metabolism under physiological and pathophysiological conditions.

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