Reciprocal renal effects of dopamine and 5-hydroxytryptamine formed within the rat kidney
- 1 November 1988
- journal article
- research article
- Published by Portland Press Ltd. in Clinical Science
- Vol. 75 (5) , 503-507
- https://doi.org/10.1042/cs0750503
Abstract
Clearance of inulin and p-aminohippurate and excretion of water and sodium were measured for eight to 11 clearance periods of 20 min duration in anaesthetized, 3% volume-expanded rats, before and after intravenous infusions of the amino acids L-dopa (L-3,4-dihydroxyphenylalanine) and 5-hydroxytryptophan. During the final two clearance periods, the peripheral decarboxylase inhibitor, carbidopa (S-.alpha.-hydrazino-3,4-dihydroxy-.alpha.-methylbenzenepropanoic acid monohydrate), was infused additionally. Renal formation of dopamine (3,4-dihydroxyphenethylamine) and 5-hydroxytryptamine was demonstrated during infusions of L-dopa and 5-hydroxytryptophan, respectively; carbidopa blocked the renal formation of these biogenic amines. During infusion of dopa, a diuresis and a natriuresis were observed; during the infusion of 5-hydroxytryptophan, slight reductions in clearances of inulin and p-aminohippurate, but significant reductions in sodium and water excretion, were measured. The addition of carbidopa diminished diuretic and natriuretic responses to dopa as renal dopamine excretion decreased; the infusion of carbidopa also ameliorated the antinatriuretic and antidiuretic effects of 5-hydroxytrytophan, as 5-hydroxytryptamine excretion decreased. Although dopa and 5-hydroxytryptophan are substrates for the same enzyme, aromatic L-amino-acid decarboxylase, simultaneous infusions of both amino acids at comparable rates gave no evidence of competitive inhibition of amine synthesis. However, the infusion of dopa, after 5-hydroxytryptophan, decreased its antinatriuretic and antidiuretic effects. These data raise the possibility that dopamine and 5-hydroxytryptamine are formed as reciprocal intrarenal hormones by the identical enzyme, aromatic L-amino-acid decarboxylase, which is located within cells of the renal tubule.This publication has 2 references indexed in Scilit:
- Dynamics of Renal Histamine in Normal Rat Kidney and in Nephrosis Induced by Aminonucleoside of PuromycinJournal of Clinical Investigation, 1982
- Aromatic l-amino acid decarboxylase activity in central and peripheral tissues and serum of rats with l-dopa and l-5-hydroxytryptophan as substratesBiochemical Pharmacology, 1981