The Estimation of Extracellular Space of Brain Tissue in Vitro

Cohen, Stephen

doi:10.1007/978-1-4615-7748-5_8

Cited by 26 publications

(5 citation statements)

References 81 publications

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“…At present it is not possible to separate these two phases reliably in brain slices. Firstly, the interstitial space volume can only be roughly determined (Cohen, 1972;Lund-Andersen, 1974) and, secondly, the slices may not become homogeneously filled with exogenous label during short-term incubations (cf. Korpi and Oja, 1981).…”

Section: Calculationsmentioning

confidence: 99%

Kinetics of Tryptophan Influx into Brain Slices Depleted of Sodium and Loaded withl‐Histidine

Korpi

1983

Journal of Neurochemistry

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The kinetics of tryptophan influx were studied with rat brain slices preloaded with L-histidine and/or depleted of sodium ions. The best fits of the data (velocity of influx versus tryptophan concentration) were computed by use of a model consisting of a saturable (Michaelis-Menten type) and an unsaturable (diffusional) component with an iterative nonlinear regression analysis. Sodium depletion of the slices reduced the maximal velocity of saturable influx. In histidine-preloaded slices, depleted or not depleted of sodium ions, the most marked alteration again occurred in the maximal velocity, which more than doubled. Slices preloaded with histidine contained greatly elevated levels of glutamine and histidine, which may have stimulated the influx by exchange with extracellular tryptophan even in the absence of sodium ions. The maximal velocity was higher with increasing concentration of large neutral amino acids in slices at the start of the influx measurements. The influx of tryptophan in brain cells is apparently modified by changes in the intracellular amino acid pool, which, when increased, also counteracts the effect of sodium depletion on the tryptophan influx.

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Section: Calculationsmentioning

confidence: 99%

Kinetics of Tryptophan Influx into Brain Slices Depleted of Sodium and Loaded withl‐Histidine

Korpi

1983

Journal of Neurochemistry

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“…This has no effect on computed values of the heat of reaction, activation energies, or Kt; it decreases the 106 AIB UPTAKE BY BRAIN SLICES kinetic constants V., and k1,U compared to constants for uptake expressed in umole/g intracellular water.min by the constant factor (g intracellular water)/(g final wet wt. of tissue) (Cohen, 1972a).…”

Section: Methodsmentioning

confidence: 99%

“…Because of unresolved problems in interpreting extracellular space measurements (Cohen, 1972a), the rate of initial uptake was computed in units of ,mole/g final wet wt. tissue.min instead of #smole/g intracellular water.…”

Section: Methodsmentioning

confidence: 99%

The rate equation and activation energies for the uptake of α‐aminoisobutyric acid by mouse brain slices

Cohen¹

1973

The Journal of Physiology

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“…It includes the true extracellular fluid and any intracellular fluid that is freely accessible without transport to that substance. Since the cut surfaces of brain slices may be selectively permeable, the functional extracellular fluid depends on the substance (Cohen, 1972). (---), concentration ratio where concentration of amino acid in tissue water is equal to its concentration in the medium.…”

Section: Methodsmentioning

confidence: 99%

Rate Equations and Kinetics of Uptake of α‐Aminoisobutyric Acid and γ‐Aminobutyric Acid by Mouse Cerebrum Slices Incubated in Media Containing L(+)‐Lactate or a Mixture of Succinate, L‐Malate, and Pyruvate as the Energy Source

Cohen

1985

Journal of Neurochemistry

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Influx of alpha-aminoisobutyric acid (AIB) and gamma-aminobutyric acid (GABA) by mouse cerebrum slices incubated with L-lactate or a mixture of succinate, L-malate, and pyruvate (SMP) as the energy source follows the phenomenological rate equation for influx from pyruvate and glucose media: v = Vmax/(1 + Kt/S) + kuS, where v is rate and S is concentration of amino acid. There are two kinetically distinct, parallel components for concentrative uptake, one saturable, and one unsaturable. Rates are less with lactate than with pyruvate and still less with SMP (only GABA was studied), disproving the hypotheses that lower rates with pyruvate compared to glucose are due to an abnormal redox state in the tissue or to a Krebs cycle unbalanced by input at only one point. The carriers for AIB and GABA are qualitatively different. In lactate medium the capacity of each AIB carrier is unchanged but its affinity is reduced to one-third. In lactate and SMP media, the capacity of the saturable GABA carrier is diminished although its affinity is increased. Rates from these media with added glucose or a glucose analog confirm that amino acid and glucose fluxes are not coupled.

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The Estimation of Extracellular Space of Brain Tissue in Vitro

Cited by 26 publications

References 81 publications

Kinetics of Tryptophan Influx into Brain Slices Depleted of Sodium and Loaded withl‐Histidine

Kinetics of Tryptophan Influx into Brain Slices Depleted of Sodium and Loaded withl‐Histidine

The rate equation and activation energies for the uptake of α‐aminoisobutyric acid by mouse brain slices

Rate Equations and Kinetics of Uptake of α‐Aminoisobutyric Acid and γ‐Aminobutyric Acid by Mouse Cerebrum Slices Incubated in Media Containing L(+)‐Lactate or a Mixture of Succinate, L‐Malate, and Pyruvate as the Energy Source

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