The acute effects of oral (‐)‐tryptophan in human subjects.

Greenwood, M. H.; Lader, M.; Kantameneni, BD; Curzon, G.

doi:10.1111/j.1365-2125.1975.tb01572.x

Cited by 74 publications

(32 citation statements)

References 38 publications

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“…Finally, regarding the safety of L-Trp, sleepiness, headache, nausea, postural discomfort, and paleness and diarrhea were observed in the subjects administered L-Trp at doses more than 4 g accompanying the increases in Trp levels in serum. Similar adverse reactions to L-Trp have been also reported (Greenwood et al, 1975;Yuwiler et al, 1981;Lieberman et al, 1984). It was concluded that a single administration of L-Trp was tolerated up to 4 g. In summary, the results of this study have demonstrated that IS was highly bound to serum protein and the major renal elimination route for IS was renal tubular secretion in humans.…”

Section: Discussionsupporting

confidence: 66%

In Vivo Kinetics of Indoxyl Sulfate in Humans and Its Renal Interaction with Angiotensin-Converting Enzyme Inhibitor Quinapril in Rats

Fujita¹,

Ishihara²,

Yasuda³

et al. 2012

J Pharmacol Exp Ther

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Indoxyl sulfate (IS) is an organic anion uremic toxin that accumulates in patients with chronic kidney disease (CKD). The aims of this study were to examine the kinetic profiles of IS in humans at a steady state after multiple doses of L-Trp, a precursor of IS, and the in vivo interaction of IS with the angiotensin-converting enzyme inhibitor quinapril, whose active metabolite is a substrate of organic anion transporter 3 (OAT3) in rats. First, 12-h kinetics after single doses of Trp (2, 4, and 8 g) were examined in two healthy volunteers. Second, 24-h kinetics after a single dose of 2 g of Trp was studied in six volunteers. Third, 35-h kinetics after single and multiple doses of 2 g of Trp were examined in five volunteers. In anesthetized rats, quinapril or probenecid, an inhibitor of OATs, was given intravenously before IS, and blood and urine samples were taken until 90 min. Trp and IS concentrations were determined by high-performance liquid chromatography. Ultrafiltration was used to measure serum unbound IS concentrations. Renal tubular secretion of IS accounted for more than 90% of its renal clearance in the steady state of serum IS levels after multiple doses in humans. In animals, the serum area under the curve of IS increased in conjunction with a decrease in renal clearances after coadministration of IS with quinapril or probenecid. It is concluded that quinapril may inhibit the urine excretion of IS via OAT3-mediated renal tubular transport in patients with CKD.

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Section: Discussionsupporting

confidence: 66%

In Vivo Kinetics of Indoxyl Sulfate in Humans and Its Renal Interaction with Angiotensin-Converting Enzyme Inhibitor Quinapril in Rats

Fujita¹,

Ishihara²,

Yasuda³

et al. 2012

J Pharmacol Exp Ther

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“…Of course, sleep parameters were determined in a group of patients not complaining of insomnia. Unlike other studies [14,15,19] we did not observe an increase in drowsiness.…”

Section: Discussioncontrasting

confidence: 55%

Effects of <i>l</i>-Tryptophan and Various Diets on Behavioral Functions in Essential Hypertensives

et al. 1989

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The effects of tryptophan in combination with two different diets (high-carbohydrate and high-protein diet) on behavioral parameters such as mood, sleep and performance were chronically studied in a group of 34 hypertensive patients undergoing a trial of testing the antihypertensive properties of l-tryptophan. While no major changes in mood were observed, there was a tendency for sleep latency to decrease and sleep duration to increase following tryptophan intake in the intragroup analysis. The administration of tryptophan caused a significant improvement on performance in a concentration task. No significant dietary effects were observed either in combination with tryptophan or in the placebo group. These data again demonstrate behavioral relevance of the precursor amino acid l-tryptophan and suggest a long-term improvement in partial aspects of performance behavior.

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“…Previously, Greenwood, Lader, Kantameneni, & Curzon (1975) reported an increase in the voltage of the 4.0-7.5 Hz and 2.4-4.0 Hz frequency bands after tryptophan loading. While these authors did not report any change in the alpha band, they recorded the EEG during performance of a reaction time task, an experimental situation which may have precluded effects on alpha activity.…”

Section: Discussionmentioning

confidence: 99%