Summary
Oral tryptophan loading and serotonin (5-HT) uptake by platelets were investigated as an approach to the study of central serotonergic mechanisms in patients with essential hypertension. Single oral doses of L-tryptophan (50 mg/kg body weight) lowered blood pressure significantly 90–120 min after administration in 14 patients with essential hypertension, but not in normotensive controls. Baseline measurements (without tryptophan loading) of 5-HT uptake by platelets did not differ between hypertensive and normotensive persons. Whereas L-tryptophan changed the uptake kinetics and increased 5-HT uptake in normal controls, these effects were not observed — or occurred to a much lesser degree — in hypertensive patients. It is suggested that in human essential hypertension central serotonergic mechanisms are involved in pathogenetic mechanisms. The tryptophan-in-duced lowering of blood pressure could be attributable to the enhancement of central 5-HT synthesis.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Abbreviations
- 5-HT:
-
5-hydroxytryptamine, i.e. serotonin
- PRP:
-
platelet rich plasma
References
Aghajanian GK, Asher LM (1971) Histochemical fluorescence of raphe neurons: selective enhancement by tryptophan. Science 172:1159–1161
Aghajanian GK (1972) Influence of drugs on the firing of serotonin containing neurons in brain. Fed Proc 31:91–96
Bhargava KP, Raina N, Misra N, Shanker K, Vrat S (1979) Uptake of serotonin by human platelets and its relevance to CNS involvement in hypertension. Life Sci 25:195–199
Björklund AB, Falck B, Stenevi V (1971) Microspectrofluorimetric characterization of monoamine in the central nervous system: evidence for a new neuronal monoamine-like compound. Prog Brain Res 34:63–73
Eccleston D, Ashcroft GW, Crawford TBB (1965) 5-Hydroxyindole metabolism in rat brain. A study of intermediate metabolism using the technique of tryptophan loading. II. Applications and drug studies. J Neurochem 12:493–503
Feltkamp H, Meurer KA (1982) Serotonin dependent decrease of blood pressure in essential hypertension after oral tryptophan loading. IX World Congress of Cardiology, Moscow, Abstracts, Vol 1, No. 220
Fernstrom JD, Wurtman RJ (1971) Brain serotonin content: physiological dependency on plasma tryptophan levels. Science 173:149–152
Green AR, Koslow SK, Costa E (1973) Identification and quantitation of a new indolealkylamine in rat hypothalamus. Brain Res 51:371–374
Green AR (1978) The effects of dietary tryptophan and its peripheral metabolism on brain 5-hydroxytryptamine synthesis and function. In: Youdim MBH, Lovenberg W, Sharman DF, Lagnado JR (eds) Essays in Neurochemistry and Neuropharmacology. John Wiley&Sons, Chichester New York Brisbane Toronto, Vol 3, pp 104–127
Kamal LA, Le Quan-Bui KH, Meyer Ph (1983) Decreased uptake and content of serotonin in blood platelets in hypertensive patients. 1st Eur Meet Hypertension, Milan, Abstr. 206
Kuhn DM, Wolf WA, Lovenberg LW (1980) Review of the role of the central serotonergic neuronal system in blood pressure regulation. Hypertension 2:243–255
Laubscher A, Pletscher A (1979) Uptake of 5-hydroxytryptamine in blood platelets and its inhibition by drugs: role of plasma membrane and granular storage. J Pharm Pharmacol 31:284–289
Marsden CA, Curzon G (1974) Effect of lesions and drugs on brain tryptamine. J Neurochem 23:1171–1176
Møller SE (1981) Pharmacokinetics of tryptophan, renal handling of kynurenine and the effect of nicotinamide on its appearance in plasma and urine following L-tryptophan loading of healthy subjects. Eur J Clin Pharmacol 21:137–142
Paasonen MK (1968) Platelet 5-hydroxytryptamine as a model in pharmacology. Ann Med Exp Fenn 46:416–422
Pletscher A (1968) Metabolism, transfer and storage of 5-hydroxytryptamine in blood platelets. Br J Pharmacol Chemother 32:1–6
Pletscher A (1978) Platelets as models for monoaminergic neurons. In: Youdim MBH, Lovenberg W, Sharman DF, Lagnado JR (eds) Essays in Neurochemistry and Neuropharmacology. John Wiley&Sons, Chichester New York Brisbane Toronto, Vol 3, pp 50–101
Saavedra JM (1973) Effect of drugs on the tryptamine content of rat tissues. J Pharmacol Exp Ther 185:523–529
Sneddon JM (1973) Blood platelets as a model for monoamine-containing neurons. In: Kerkut GA, Philhsi JW (eds) Progress in Neurobiology, Vol 1, part 2. Pergamon, Oxford, pp 151–198
Sved AF, Fernstrom JD, Wurtman RJ (1979) Tyrosine administration reduces blood pressure and enhances brain norepinephrine release in spontaneously hypertensive rats. Proc Natl Acad Sci USA 76:3511
Yuwiler A (1973) Conversion of D- and L-tryptophan to brain serotonin and 5-hydroxyindoleacetic acid and to blood serotonin. J Neurochem 20:1099–1109
Yuwiler A, Brammer GL, Moreley JE, Raleigh MJ, Flannery JW, Geller E (1981) Short-term and repetitive administration of oral tryptophan in normal men. Effects on blood tryptophan, serotonin and kynurenine concentrations. Arch Gen Psychiatry 38:619–626
Author information
Authors and Affiliations
Additional information
Dedicated to Professor Dr. W. Kaufmann on the occasion of his 60th birthday
Rights and permissions
About this article
Cite this article
Feltkamp, H., Meurer, K.A. & Godehardt, E. Tryptophan-induced lowering of blood pressure and changes of serotonin uptake by platelets in patients with essential hypertension. Klin Wochenschr 62, 1115–1119 (1984). https://doi.org/10.1007/BF01782468
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01782468