Blood and urine 5-hydroxytryptophan and 5-hydroxytryptamine levels after administration of two 5-hydroxytryptamine precursors in normal man.
Six healthy male subjects received equimolar amounts of two 5-hydroxytryptamine (5-HT) precursors, 5-hydroxy-L-tryptophan (5-HTP) and gamma-L-glutamyl-5-hydroxy-L-tryptophan (glu-5-HTP), on two occasions in a randomised cross-over study. There were marked increases in urinary 5-HTP and 5-HT excretion after infusion of both compounds. Mean urinary excretion rate of 5-HT, which was < 0.7 nmol min-1 before dosing, rose to a peak value of 412 +/- 92 nmol min-1 at the end of 5-HTP infusion and 303 +/- 29 nmol min-1 after administration of glu-5-HTP. This occurred without significant changes in blood 5-HT levels measured in platelet-rich plasma. These findings provide further evidence that the increase in urine 5-HT after administration of both 5-HT precursors is largely due to 5-HT synthesised within the kidney.
Wa
T C
TC
Department of Medicine, Royal Infirmary, Edinburgh.
Burns
N J
NJ
Williams
B C
BC
Freestone
S
S
Lee
M R
MR
D006916:5-Hydroxytryptophan / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology* / Q000652:urine; D000328:Adult; D018592:Cross-Over Studies; D004151:Dipeptides / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D008297:Male; D011355:Prodrugs / Q000008:administration & dosage / Q000494:pharmacology*; D012701:Serotonin / Q000097:blood* / Q000652:urine
D004151:Dipeptides; D011355:Prodrugs; C083320:gamma-glutamyl-5-hydroxytryptophan; D012701:Serotonin; D006916:5-Hydroxytryptophan