Distribution of free amino acids and related substances in organs of the rat

Awapara, Jörge; Landua, Alton J.; Fuerst, Robert

doi:10.1016/0006-3002(50)90191-0

Cited by 58 publications

(13 citation statements)

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“…Taurine (2-aminoethanesulfonic acid) is one of the most abundant free amino acids in several organs of the body and plays an important role in a variety of essential biological processes (Awapara et al 1950;Wright et al 1986). Taurine is involved in neurodevelopment and membrane stabilization and may be a neuromodulator (Huxtable 1992); however, the best-understood function of taurine in the central nervous system is as an osmolyte (Pasantes Morales and Schousboe 1988;Pasantes-Morales et al 2002).…”

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confidence: 99%

Regulation of taurine transport in rat hippocampal neurons by hypo‐osmotic swelling

Olson¹,

Martinho

2006

Journal of Neurochemistry

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Taurine, an important mediator of cellular volume regulation in the central nervous system, is accumulated into neurons and glia by means of a highly specific sodium-dependent membrane transporter. During hyperosmotic cell shrinkage, net cellular taurine content increases as taurine transporter activity is enhanced via elevated gene expression of the transporter protein. In hypo-osmotic conditions, taurine is rapidly lost from cells by means of taurine-conducting membrane channels. We reasoned that changes in taurine transporter activity also might accompany cell swelling to minimize re-accumulation of taurine from the extracellular space. Thus, we determined the kinetic and pharmacological characteristics of neuronal taurine transport and the response to osmotic swelling. Accumulation of radioactive taurine is strongly temperature dependent and occurs via saturable and non-saturable pathways. At concentrations of taurine expected in extracellular fluid in vivo, 98% of taurine accumulation would occur via the saturable pathway. This pathway obeys Michaelis-Menten kinetics with a K m of 30.0 ± 8.8 lM (mean ± SE) and J max of 2.1 ± 0.2 nmol/mg protein min. The saturable pathway is dependent on extracellular sodium with an effective binding constant of 80.0 ± 3.1 mM and a Hill coefficient of 2.1 ± 0.1. This pathway is inhibited by structural analogues of taurine and by the anion channel inhibitors, 4,4¢-diisothiocyanostilbene-2, 2¢-disulfonic acid (DIDS) and 5-nitro-2-(3 phenylpropylamino) benzoic acid (NPPB). NPPB, but not DIDS, also reduces the ATP content of the cell cultures. Osmotic swelling at constant extracellular sodium concentration reduces the J max of the saturable transport pathway by approximately 48%, increases K diff for the non-saturable pathway by 77%, but has no effect on cellular ATP content. These changes in taurine transport occurring in swollen neurons in vivo would contribute to net reduction of taurine content and resulting volume regulation.

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confidence: 99%

Regulation of taurine transport in rat hippocampal neurons by hypo‐osmotic swelling

Olson¹,

Martinho

2006

Journal of Neurochemistry

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“…The comparative absence of aspartate and glutamate in invertebrate muscle may be correlated with the fact that a large fraction of the internal potassium can be balanced by organic phosphorus compounds which are presumably associated with the contractile mechanism, for Engel & Gerard (1935) Vertebrate excitable tissues, on the other hand, contain only small amounts of free amino-acids. Awapara, Landua & Fuerst (1950) have made a fairly comprehensive survey of the amino-acid content of the tissues of the rat; their values for the Biochem. 1952, 52 excitable tissues have been recalculated and are given in Table 7 in m-moles/kg.…”

Section: Resultsmentioning

confidence: 99%

The free amino-acids of invertebrate nerve

Lewis

1952

Biochemical Journal

133

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“…Glutamate decarboxylase (GAD) catalyses the production of GABA molecules, which, in comparison with any other inhibitory neurotransmitters, are widespread in the vertebrate brain. There are two forms of GAD, GAD65 and GAD67, with enzymatic characteristics and a subcellular distribution stimulated by the two genes (19).…”

Section: Introductionmentioning

confidence: 99%