Transport of neutral amino acids from feline cerebrospinal fluid

Snodgrass, S. Robert; Rw, Cutler; Kang, ES; Lorenzo, AV

doi:10.1152/ajplegacy.1969.217.4.974

Cited by 69 publications

(13 citation statements)

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“…have been discussed previously (Ashcroft, Dow & Moir, 1968;Ashcroft, Crawford, Dow & Moir, 1969 Cutler & Lorenzo (1968) and Snodgrass, Cutler, Song Kang & Lorenzo (1969) found that the clearances of other amino acids from c.s.f. also involve saturable carrier-mediated systems.…”

Section: Discussionmentioning

confidence: 75%

The transport of L‐tryptophan from cerebrospinal fluid in the dog

Geddes¹,

Martin²,

Moir³

1973

The Journal of Physiology

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1. Endogenous tryptophan is uniformly distributed in dog cerebrospinal fluid (c.s.f.) and is about one tenth of the normal fasting plasma level. 2. Using a recirculatory ventriculo‐cisternal perfusion technique in conscious dogs it was found that L‐tryptophan was removed from c.s.f. by a non‐saturable mechanism in addition to bulk absorption of c.s.f. The clearance of L‐tryptophan from c.s.f. was unaffected by thiopentone anaesthesia. 3. Dialysis of dog plasma against an artificial c.s.f. solution containing L‐tryptophan demonstrated that a large proportion of the tryptophan in dog plasma was protein‐bound and that the unbound diffusible proportion would equilibrate with tryptophan concentrations equivalent to those normally found in dog c.s.f. 4. Use of an open‐circuit ventriculo‐cisternal perfusion system in unanaesthetized dogs revealed the presence of a saturable component in the transport of tryptophan from c.s.f. 5. As [14C] L‐tryptophan infused into a recirculatory perfusion system produced no radioactively labelled metabolites, it was concluded that removal of tryptophan from c.s.f. by cerebral metabolism does not contribute substantially to maintaining the low levels of tryptophan in c.s.f. but that brain uptake associated with protein‐binding may give rise to a small saturable component. The results indicate that the actual concentration gradient of tryptophan between plasma and c.s.f. is much less than it appears from the total concentration of tryptophan in the two fluids, and that the mechanism by which the c.s.f. — plasma distribution of tryptophan is maintained is mainly attributable to simple diffusion.

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Section: Discussionmentioning

confidence: 75%

The transport of L‐tryptophan from cerebrospinal fluid in the dog

Geddes¹,

Martin²,

Moir³

1973

The Journal of Physiology

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“…Overlapping between systems exists when most amino acids are transported by more than one system (Cohen and Lajtha, 1972). The difference existing between the free amino acid levels in plasma and CNS can be the consequence of restriction into the CNS from blood, rapid exit from the CNS by active process, rapid metabolic utilization, or a combination of the above (Bito et al, 1966;Levin et al, 1966a and b;Snodgrass et al, 1969). On the other hand, it was claimed that amino acids are transported from CSF to blood through the brain (Snodgrass et al, 1969) and that influx and/or efflux are affected by drugs and analogues of amino acids in different ways (Gaull et al, 1974).…”

Section: Discussionmentioning

confidence: 99%

“…Influx and efflux of amino acids from the brain occurs by specific mechanisms. Such mechanisms might also serve to regulate the brain amino acid concentration (Snodgrass et al, 1969).…”

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confidence: 99%

Mutual effects of morphine and aspartic acid on brain levels in mice

et al. 1977

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Abstract. The antagonistic effect of aspartic acid on some effects of morphine is known. This is mainly seen in the development of dependence on and tolerance to morphine. We investigated the mutual effects of the two drugs on the brain levels in mice.A total of 120 mice were examined in two groups. One group was given an intraperitoneal injection of tritiated aspartic acid. The other group was given tritiated aspartic acid and aspartic acid (30 mg/kg). Thirty mice in each group were injected with 15 mg/kg of morphine i.v. simultaneously. Thus we obtained four different groups of mice. Ten mice from each group were killed after a time elapse of 15, 30, and 60 min consecutively, and the morphine content and radioactivity on their brains were determined. Other samples of brain homogenates were deproteinized and their radioactivity was measured.Morphine increased the brain levels of labeled aspartic acid, while the brain content of morphine was decreased. It was thought that the results might be related rather to a heteroexchange existing between the morphine content in the central nervous system (CNS) and aspartic acid in the circulation. In addition aspartic acid can possibly stimulate or inhibit the efflux or influx of morphine in the CNS.

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“…There is recent evidence that a wide range of amino acids is transported by a carrier mediated process across the blood-brain (cerebral capillary endothelium) and blood-cerebrospinal fluid (choroid plexus) barriers (Betz, Gilboe, and Drewes, 1975;Lajtha, 1974;Oldendorf, 1971;Snodgrass, Cutler, Kang, and Lorenzo, 1969). In the case of glycine, there is experimental evidence that this neutral amino acid is actively transported into brain slices (Lajtha and Toth, 1963), in uitro and in uiuo choroid plexus (Caruthers and Lorenzo, 1974;Coben, Cotlier, Beaty, and Becker, 1971).…”

Section: Introductionmentioning

confidence: 99%

Movement of glycine across the blood‐brain barrier of the rabbit

Pollay

1976

J. Neurobiol.

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The single pass clearance of glycine from the cerebral capillary bed was measured in the rabbit with the indicator diffusion method. It was shown that glycine was extracted to the same degree as fructose (ca..07). The concentration of glycine injected into the carotid artery was varied some 700-fold without significantly affecting the clearance of this amino acid in transit through the brain. Cross inhibition of the unidirectional movement of glycine was not demonstrable. These present results and most previous studies suggest that this putative neurotransmitter does not cross the blood-brain barrier by a carrier mediated process.

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Transport of neutral amino acids from feline cerebrospinal fluid

Cited by 69 publications

References 0 publications

The transport of L‐tryptophan from cerebrospinal fluid in the dog

The transport of L‐tryptophan from cerebrospinal fluid in the dog

Mutual effects of morphine and aspartic acid on brain levels in mice

Movement of glycine across the blood‐brain barrier of the rabbit

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