Permeability of the liver cell membrane to quinolinate

Elliott, Keith; Pogson, Christopher I.; Smith, Stephen A.

doi:10.1042/bj1640283

Cited by 13 publications

(16 citation statements)

References 17 publications

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“…These results agreed with the report on isolated hepatocytes of rainbow trout (Walton and Cowey 1979). It has been reported that the permeability of quinolinic acid to the plasma membrane is different among animals (Elliot et al 1977). No effect of quinolinic acid on gluconeogenesis in eel and rainbow trout hepatocytes seemed to be due to the impermeability of the cell membrane to quinolinic acid or to the properties of the enzyme itself.…”

Section: -3a Effects Of Inhibitorssupporting

confidence: 92%

Studies on Eel Liver Functions Using Perfused Liver and Primary Cultured Hepatocytes

Hayashi¹,

Kumagai²

2008

Aqua-BioSci. Monogr. (ABSM)

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Perfused eel livers, isolated eel hepatocytes, and cultured eel hepatocytes are used to investigate eel liver functions such as gluconeogenesis, glycogen synthesis, and lipoprotein synthesis and methods for preparation are described. A novel phosphoenolpyruvate (PEP) synthesis pathway from pyruvate in gluconeogenesis in eel liver was elucidated and PEP synthesis pathways in eel, rat, and pigeon livers were compared. Glycogen synthesis from pyruvate, lactate, and glucose was investigated by using cultured eel hepatocytes. It was found that 10-6 or 10-7 M glucagon didn't stimulate glycogen degradation in the presence of pyruvate but stimulated glycogen degradation in the presence of lactate. Glycogen synthesis from pyruvate was observed even when 10-6 or 10-7 M glucagon was present. The characteristics of the lipoprotein synthesized and secreted by cultured eel hepatocytes are clarified. Thyroxine and eel serum high-density lipoprotein (HDL) stimulated the lipoprotein synthesis by cultured eel hepatocytes. In the presence of estradiol-17β, eel serum HDL stimulated vitellogenin synthesis in eel hepatocytes. HDL specifically bound to eel hepatocytes and the ligand of HDL receptor in the plasma membrane of eel hepatocytes was identified to be ganglioside GM4 of eel serum HDL.

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Section: -3a Effects Of Inhibitorssupporting

confidence: 92%

Studies on Eel Liver Functions Using Perfused Liver and Primary Cultured Hepatocytes

Hayashi¹,

Kumagai²

2008

Aqua-BioSci. Monogr. (ABSM)

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“…This concentration is greater than that required (0.1 or 0.5 mm, depending on whether ferrous quinolinate or free quinolinate is the inhibitory species) for half-maximal inhibition of phosphoenolpyruvate carboxykinase in vitro (McDaniel et al, 1972b). The liver-cell membrane is relatively permeable to extracellular quinolinate (Elliott et al, 1977). Since the kinetics of efflux of endogenous quinolinate from the hepatocyte are unknown, it is not possible without direct measurement of intracellular quinolinate to determine whether these intracellular concentrations are indeed achieved.…”

Section: Quinolinic Acidformation By Liver Cellsmentioning

confidence: 98%

“…Quinolinic acid itself, however, is only inhibitory at concentrations in excess of 1 mM, an observation that cannot be attributed to poor cellular penetration (Elliott et al, 1977). If quinolinate alone is responsible for the inhibition by tryptophan of gluconeogenesis, then its rate of synthesis from tryptophan must be sufficiently rapid to attain intracellular concentrations greater than 1 mM.…”

Section: Quinolinic Acidformation By Liver Cellsmentioning

confidence: 99%

“…of cells. Assuming a dry-weight/wetweight conversion factor of 3.7 (Krebs et al, 1974) and that 1 g of cells contains 0.7 ml of intracellular water (Elliott et al, 1977), this would yield an intracellular quinolinate concentration of 4.4mm. This concentration is greater than that required (0.1 or 0.5 mm, depending on whether ferrous quinolinate or free quinolinate is the inhibitory species) for half-maximal inhibition of phosphoenolpyruvate carboxykinase in vitro (McDaniel et al, 1972b).…”

Section: Quinolinic Acidformation By Liver Cellsmentioning

confidence: 99%

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The metabolism of l-tryptophan by isolated rat liver cells. Quantification of the relative importance of, and the effect of nutritional status on, the individual pathways of tryptophan metabolism

Smith¹,

Carr²,

Pogson³

1980

Biochemical Journal

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1. The metabolism of L-tryptophan by liver cells prepared from fed and 48 h-starved rats was studied. Methods are described, with the use of L-[ring-2-14C], L-[carboxy-'4C1-and L-[benzene-ring-U-'4C]-tryptophan, for the simultaneous determination of tryptophan 2,3-dioxygenase and kynureninase activities and of the oxidation of tryptophan to CO2 and non-aromatic intermediates of the kynurenine-glutarate pathway. 2. At physiological concentrations (0.1 mM), tryptophan was oxidized by tryptophan 2,3-dioxygenase at comparable rates in liver cells from both fed and starved rats. Kynureninase activity of hepatocytes from starved rats was 50% greater than that of cells from fed rats. About 10%o of the tryptophan metabolized by tryptophan 2,3-dioxygenase was degraded completely to CO2. 3. In the presence of 0.5mm-L-tryptophan, tryptophan 2,3-dioxygenase and kynureninase activities increased 5-6-fold. Liver cells from starved rats oxidized tryptophan at about twice the rate of these from fed rats. Degradation of tryptophan to non-aromatic intermediates of the glutarate pathway and CO2 was increased only 3-fold, suggesting an accumulation of aromatic intermediates of the kynurenine pathway. 4. Rates of metabolism with 2.5 mM-L-tryptophan were not significantly different from those obtained with 0.5mM-tryptophan. 5. Rates of synthesis of quinolinic acid from 0.5mM-L-tryptophan, determined either by direct quantification or indirectly from rates of radioisotope release from L-[carboxy-"4C]-and [benzene-ring-U-'4C]tryptophan, were essentially similar. 6. At all three concentrations examined, tryptophan was degraded exclusively through kynurenine; there was no evidence of formation of either indol-3-ylacetic acid or 5-hydroxyindol-3-ylacetic acid.In the mammal, four separate pathways exist for the metabolism of L-tryptophan (see Scheme 1). These are: (i) oxidation by tryptophan 2,3-dioxygenase [L-tryptophan-02 2,3-oxidoreductase (decyclizing), EC 1.13.11.111 to kynurenine and subsequently to acetyl-CoA (the 'glutarate' pathway) or nicotinamide nucleotides (the 'NAD' pathway); (ii) transamination to yield indol-3-ylpyruvic acid, which may then be oxidized to indol-3-ylacetic acid; (iii) decarboxylation to yield the neurotransmitter tryptamine (Saavedra & Axelrod, 1973;Young et al., 1980) (Young et al., 1978). Several methods have been used to investigate the control of tryptophan oxidation by the kynurenine pathway in intact isolated liver preparations. These include measurements of rates of appearance of specific metabolites such as kynurenine (Green et al., 1976) or of removal of added tryptophan (Kim & Miller, 1969;Ng et al., 1970). The disadvantages of these methods have been discussed elsewhere (Smith & Pogson, 1980). S. A. Smith, F. P. A. Carr and C. I. Pogson kynurenine pathway has been derived from experiments with the use of specifically radiolabelled tryptophan (Altman & Gerber, 1967;Ng et al., 1970). However, interpretation of these radioisotope data is complicated because, in most instances, a racemic mixture of D-...

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“…It is suggested that liver important role in NAD+ synthesis from costeroid-treated rats rendered deficient in nicotinamide, nicotinic acid and tryptophan (Greengard et aL, 1966(Greengard et aL, , 1968. The interpretation of these latter findings in mice and rats is complicated because of species differences in tryptophan metabolism (Monroe, 1968;Badawy & Evans, 1976b,c;Elliott et al, 1977;Smith et al, 1978) and the possible complex physiological changes caused in rats by the above nutritional deficiencies.…”

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confidence: 99%

Possible involvement of the enhanced tryptophan pyrrolase activity in the corticosterone- and starvation-induced increases in concentrations of nicotinamide-adenine dinucleotides (phosphates) in rat liver

Badawy¹

1981

Biochemical Journal

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1. Deoxycorticosterone, which does not enhance tryptophan pyrrolase activity, also fails to alter the concentrations of the NAD(P) couples in livers of fed rats, whereas corticosterone increases both pyrrolase activity and dinucleotide concentrations. 2. Starvation of rats increases serum corticosterone concentration, lipolysis, tryptophan availability to the liver, tryptophan pyrrolase activity and liver [NADP(H)]. Glucose prevents all these changes. 3. The beta-adrenoceptor-blocking agent propranolol prevents the starvation-induced lipolysis and the consequent increase in tryptophan availability to the liver, but does not influence the increase in serum corticosterone concentration, liver pyrrolase activity and [NADP(H)]. 4. Actinomycin D, which prevents the starvation-induced increases in liver pyrrolase activity and [NADP(H)], does not affect those in serum corticosterone concentration and tryptophan availability to the liver. 5. Allopurinol, which blocks the starvation-induced enhancement of pyrrolase activity, also abolishes the increases in liver [NADP(H)], but not those in serum corticosterone concentration or tryptophan availability to the liver. 6. It is suggested that liver tryptophan pyrrolase activity plays an important role in NAD+ synthesis from tryptophan in the rat.

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Permeability of the liver cell membrane to quinolinate

Cited by 13 publications

References 17 publications

Studies on Eel Liver Functions Using Perfused Liver and Primary Cultured Hepatocytes

Studies on Eel Liver Functions Using Perfused Liver and Primary Cultured Hepatocytes

The metabolism of l-tryptophan by isolated rat liver cells. Quantification of the relative importance of, and the effect of nutritional status on, the individual pathways of tryptophan metabolism

Possible involvement of the enhanced tryptophan pyrrolase activity in the corticosterone- and starvation-induced increases in concentrations of nicotinamide-adenine dinucleotides (phosphates) in rat liver

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