Natural‐abundance <sup>13</sup>C NMR of brain

Bárány, Michael; Arús, Carlos; Chang, Ya‐Hui

doi:10.1002/mrm.1910020312

Cited by 72 publications

(4 citation statements)

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“…Inverse gating with a delay time of 3 s was used to minimize nuclear Overhauser effects . Assignments were made on the basis of previous reports (Bárány et al ., 1985 ;London, 1988) . The total level of acetate in serum extracts was quantified by 'H NMR spectroscopy ; 500-MHz 'H NMR spectra were accumulated using a 40°pulse angle, 15-s relaxation delay, and a sweep width of 5 kHz .…”

Section: Methodsmentioning

confidence: 99%

Glial Formation of Pyruvate and Lactate from TCA Cycle Intermediates: Implications for the Inactivation of Transmitter Amino Acids?

Hassel

Sonnewald

1995

Journal of Neurochemistry

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Cerebral formation of lactate via the tricarboxylic acid (TCA) cycle was investigated through the labeling of lactate from [2‐13C]acetate and [1‐13C]glucose as shown by 13C NMR spectroscopy. In fasted mice that had received [2‐13C]acetate intravenously, brain lactate C‐2 and C‐3 were labeled at 5, 15, and 30 min, reflecting formation of pyruvate and hence lactate from TCA cycle intermediates. In contrast, [1‐13C]glucose strongly labeled lactate C‐3, reflecting glycolysis, whereas lactate C‐2 was weakly labeled only at 15 min. These data show that formation of pyruvate, and hence lactate, from TCA cycle intermediates took place predominantly in the acetate‐metabolizing compartment, i.e., glia. The enrichment of total brain lactate from [2‐13C]acetate reached ∼1% in both the C‐2 and the C‐3 position in fasted mice. It was calculated that this could account for 20% of the lactate formed in the glial compartment. In fasted mice, there was no significant difference between the labeling of lactate C‐2 and C‐3 from [2‐13C]acetate, whereas in fed mice, lactate C‐3 was more highly labeled than the C‐2, reflecting adaptive metabolic changes in glia in response to the nutritional state of the animal. It is hypothesized that conversion of TCA cycle intermediates into pyruvate and lactate may be operative in the glial metabolism of extracellular glutamate and GABA in vivo. Given the vasodilating effect of lactate on cerebral vessels, which are ensheathed by astrocytic processes, conversion of glutamate and GABA into lactate could be one mechanism mediating increases in cerebral blood flow during nervous activity.

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Section: Methodsmentioning

confidence: 99%

Glial Formation of Pyruvate and Lactate from TCA Cycle Intermediates: Implications for the Inactivation of Transmitter Amino Acids?

Hassel

Sonnewald

1995

Journal of Neurochemistry

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“…A major increase is seen in the height of the resonance of the polyunsaturated carbons at 128.79 ppm. On the other hand, no significant changes are noted in the following peak heights: methyl and alcoholic carbons of lactic acid at 20.98 and 69.35 ppm, respectively; total carbons from the methyl group of creatine and the C2 carbons of TV-acetylaspartate, glutamate, and glutamine at 54.70 ppm; inositol carbons at 72.04, 73.31, and 75.25 ppm; and carbonyl carbons at 174.61-175.34 ppm (Bárány et al, 1985a). Free halothane is visible in the upper spectrum of Figure 1; it produces the peak at 50.68 ppm (-CHBrCl) and a quartet with center peaks at 120.23 and 123.29 ppm (CF3-).…”

Section: Resultsmentioning

confidence: 87%

“…The difference spectrum between anesthetized and control rats shows an increase for the peaks characteristic for the membranes, such as 15, 30.5, and 129 ppm, and decreases for peaks corresponding to metabolites such as 34, 55, 63, 72-73, and 182 ppm. These latter peaks may be tentatively assigned (Bárány et al, 1985a) to glutamate C4 (34.30 ppm), to the methyl groups of creatine, choline, and choline derivatives " T¡ Values for vesicles and vesicles + halothane are the result of a single experiment; all other T¡ values are the average of duplicates in different samples, with ± the largest standard deviation. 6 30 µ of halothane/g of brain.…”

Section: Resultsmentioning

confidence: 99%

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Effect of halothane on the natural-abundance carbon-13 NMR spectra of excised rat brain

Bárány¹,

Chang²,

Arús³

1985

Biochemistry

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Halothane increases the intensity of the 30.5- and 129-ppm resonances in 13C nuclear magnetic resonance spectra of excised rat brain, of phospholipid vesicles prepared from chloroform-methanol extract of rat brain, and of brain excised from rats anesthetized with halothane. The 13C spin-lattice relaxation times of the 30.5- and 129-ppm resonances are increased in excised brain, or phospholipid vesicles, upon addition of halothane, and they are also increased in brain excised from rats anesthetized with halothane. Excised brain and its membrane-rich subcellular fractions interact with [14C]halothane reversibly. The interaction is virtually abolished when the phospholipids are extracted from the brain. The [14C]halothane content of the brain membranes is correlated with the halothane-induced increase in the integral of the 129-ppm resonance. From this correlation and from the phospholipid content of the membranes, a halothane concentration of 3.34 mM and a partition of 0.057 mol of halothane/mol of phospholipid may be calculated in the brain of anesthetized rats.

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Biochemistry and physiology of carbohydrates in the renal collecting duct

Kinne¹,

Grunewald²,

Ruhfus³

et al. 1997

J. Exp. Zool.

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Using 13C‐NMR analysis of cell extracts, enzymatic determination of metabolites and cofactors as well as enzyme assays on cell homogenates aerobic and anaerobic glycolysis, sorbitol formation by aldose reductase, the pentose phosphate shunt, and gluconeogenesis could be identified as the major pathways of D‐glucose metabolism in renal inner medullary collecting ducts. In flux studies it was shown that D‐glucose enters the collecting duct cells via a sodium‐independent, cytochalasin‐ and phloretin‐inhibitable transport system located at the basal‐lateral cell side. At the same side sorbitol leaves the cells during regulatory volume decrease in a calcium‐calmodulin‐dependent fashion. From cell isolation studies it is proposed that sorbitol is taken up by adjacent (interstitial) cells, converted into fructose and then recycled to the collecting duct cells. This cycle might prevent carbohydrate wasting. Thus, IMCD cells exhibit unique aspects of carbohydrate biochemistry and physiology which enable them to function in a surrounding of low oxygen tension, low substrate supply, and extreme changes in extracellular osmolality. J. Exp. Zool. 279:436–442, 1997. © 1997 Wiley‐Liss, Inc.

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Natural‐abundance ¹³C NMR of brain

Cited by 72 publications

References 25 publications

Glial Formation of Pyruvate and Lactate from TCA Cycle Intermediates: Implications for the Inactivation of Transmitter Amino Acids?

Glial Formation of Pyruvate and Lactate from TCA Cycle Intermediates: Implications for the Inactivation of Transmitter Amino Acids?

Effect of halothane on the natural-abundance carbon-13 NMR spectra of excised rat brain

Biochemistry and physiology of carbohydrates in the renal collecting duct

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Natural‐abundance 13C NMR of brain

Cited by 72 publications

References 25 publications

Glial Formation of Pyruvate and Lactate from TCA Cycle Intermediates: Implications for the Inactivation of Transmitter Amino Acids?

Glial Formation of Pyruvate and Lactate from TCA Cycle Intermediates: Implications for the Inactivation of Transmitter Amino Acids?

Effect of halothane on the natural-abundance carbon-13 NMR spectra of excised rat brain

Biochemistry and physiology of carbohydrates in the renal collecting duct

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Natural‐abundance ¹³C NMR of brain