Charlton KG, Johnson TD, Clarke DE. Vasoconstrictor and norepinephrine potentiating action of 5-hydroxykynuramine in the isolated perfused rat kidney: involvement of serotonin receptors and alpha 1-adrenoceptors.
NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1984;
328:154-9. [PMID:
6098835 DOI:
10.1007/bf00512065]
[Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Kynuramines are endogenously occurring diamines derived from tryptophan. In the present study, we have compared the pharmacological actions of 5-hydroxykynuramine (5-OH-K) with kynuramine and 5-hydroxytryptamine (5-HT) on vascular resistance changes and responsiveness to adrenergic stimuli in the isolated perfused rat kidney. 5-OH-K was found to mimic the actions of 5-HT in that it produced vasoconstriction, potentiation of alpha 1-adrenoceptor-mediated responses to norepinephrine (NE) and periarterial nerve stimulation, and displaced specific [3H]spiroperidol binding from rat cortical membranes. With regard to all parameters measured, 5-OH-K was about 15-times less active than 5-HT. Vascular responses to 5-OH-K and 5-HT were inhibited noncompetitively by ketanserin and cyproheptadine. Unlike 5-OH-K, kynuramine, failed to evoke vasoconstriction and inhibited vascular responses to NE via alpha 1-adrenoceptors. Thus, kynuramine lacks serotonin receptor agonist activity but possesses alpha 1-adrenoceptor blocking properties. In contrast, 5-OH-K potentiates NE and acts as a serotonin agonist. The present results raise the possibility that kynuramine and 5-OH-K might act as endogenous modulators of serotonergic and adrenergic mechanisms in the renal vascular bed.
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