The binding of l-tryptophan in human plasma at 37 °C

McMenamy, Rapier H.; Lund, Charles C.; Marcke, Joseph Van; Oncley, J. L.

doi:10.1016/0003-9861(61)90325-3

Cited by 67 publications

(26 citation statements)

References 10 publications

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“…These results in conjunction with the recirculatory perfusion studies seemed to indicate that the removal of tryptophan from c.s.f., by a mechanism other than bulk absorption, was probably attributable to simple diffusion. Such a diffusion-controlled distribution of tryptophan in the dog is comparable to that found in humans where the tryptophan concentration in plasma is four times that in erythrocytes, but where all the tryptophan in erythrocytes was found to be diffusible (McMenamy, Lund, Neville & Wallach, 1960) and only 25 % of the total tryptophan in plasma was ultrafiltrable (McMenamy, Lund, Van Marcke & Oncley, 1961).…”

Section: Discussionmentioning

confidence: 56%

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: 56%

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

Geddes¹,

Martin²,

Moir³

1973

The Journal of Physiology

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“…The proportion of bound tryptophan is affected by the temperature, ionic strength and pH of the solution (McMenamy et al, 1961). The portion of dialysable tryptophan in plasma can be reliably estimated in the plasma ultrafiltrate (McMenamy et al, 1961). The above studies have demonstrated that total tryptophan can be quantitatively recovered from plasma after its precipitation with trichloroacetic acid (the method used in this study), although studies with radioactive L-tryptophan (Gal, Morgan, Chatterjee & Marshall, 1964) have suggested that there is yet another small fraction of tryptophan which remains in the protein precipitate, perhaps because of incorporation into the protein.…”

Section: Discussionmentioning

confidence: 99%

“…After inverting the tube a few times, it was centrifuged at 2,500 g for 8 minutes. A 2 ml portion of plasma was transferred to Visking dialysis tubing-8/32 (Scientific Instrument Centre Ltd.) and an ultrafiltrate prepared by centrifuging at 3,000 g for 1 h at 370 C using an adaptation of the method of McMenamy, Lund, Van Mercke & Oncley (1961). This ultrafiltrate and portions of the plasma and red cell layer were transferred to separate polyethylene containers and stored at -150 C. A 2 ml sample of c.s.f.…”

Section: Animal Proceduresmentioning

confidence: 99%

“…Plasma ultrafiltrate McMenamy et al (1961) showed that the small proportion of human plasma tryptophan which was dialysable could be reliably estimated by the concentration found in an ultrafiltrate of the plasma. The dog plasma ultrafiltrates analysed in these experiments were prepared in a manner similar to that described by McMenamy et al (1961) and gave values similar to those found by Geddes (1969) for the proportion of dog plasma tryptophan which was dialysable.…”

Section: Animal Proceduresmentioning

confidence: 99%

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Interaction in the cerebral metabolism of the biogenic amines: Effect of intravenous infusion of l‐tryptophan on tryptophan and tyrosine in brain and body fluids

Moir

1971

British J Pharmacology

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Summary1. The distribution of the amino-acids tryptophan and tyrosine has been determined in plasma ultrafiltrate, whole plasma, erythrocytes, cerebrospinal fluid (c.s.f.) and various regions of the brain in dogs. 2. The effect of tryptophan administration on the distribution of both these amino-acids showed that the alterations produced in tryptophan concentration did not appear to change the concentrations of tyrosine from their normal pattern. 3. The implications of these results with regard to amino-acid transport systems in man and dog are discussed. IntroductionInteraction between the cerebral metabolism of tryptophan and dopamine has been demonstrated in dog brain (Moir, 1969;Moir & Yates, 1970;Moir, 1971). It was thought initially, in view of the experiments of Guroff & Udenfriend (1962) demonstrating that tryptophan inhibited the rate of uptake of radioactive tyrosine into rat brain, that the interaction demonstrated between the metabolism of the biogenic amines might be due to an interaction between their precursor amino-acids tryptophan and tyrosine. Because of this, concurrent estimations of these aminoacids were made in samples of various body fluids and brain regions during the experiments reported by Moir, 1971. These results are reported separately, as although they demonstrate many interesting features of the behaviour of the amino-acids, tryptophan and tyrosine, in brain and body fluids, they provide no evidence of any interaction between them.

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“…6 Trp is normally bound to albumin (approximately 80%). The serum concentration of Trp can be used as an index of several diseases: low-concentration levels of the total (free form+bound form) Trp are found in alcoholism', depressions and other mental disturbance9'10 as well as carcinoid tumors;1' the free Trp level is elevated in hepatitis and liver cirrhosis.12, 13 Several methods have been reported for the quantification of Trp in serum: fluorometric14-1', UVspectrometricls, gas chromatography-mass spectrometricls and high-performance liquid chromatographic (HPLC).20 Of these methods, since a fluorometric method based on a reaction with formaldehyde15 is fairly sensitive and selective, it was subjected to further improvement.16,17 These methods require oxidizing agents and long heating periods for the reaction and allow tryptamine to afford fluorescence.…”

mentioning

confidence: 99%

Fluorometric Determination of Tryptophan in Human Serum Using Phenylglyoxal

1993

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A simple fluorometric method is described for the determination of the total (free + albumin-bound) and free tryptophan in human serum. After deproteinization of the serum (perchloric acid precipitation for total tryptophan; ultrafiltration for free tryptophan), the samples are treated with phenylglyoxal in dilute perchloric acid to develop fluorescence. The method is sensitive and fairly selective for tryptophan in serum; the limit of detection is 0.84 nmol ml-1 in serum, thus giving a fluorescence intensity that is twice that of the blank.

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The binding of l-tryptophan in human plasma at 37 °C

Cited by 67 publications

References 10 publications

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

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

Interaction in the cerebral metabolism of the biogenic amines: Effect of intravenous infusion of l‐tryptophan on tryptophan and tyrosine in brain and body fluids

Fluorometric Determination of Tryptophan in Human Serum Using Phenylglyoxal

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