ISSN:
1432-1912
Keywords:
5-Hydroxytryptamine
;
Serotonin receptors
;
5-Hydroxykynuramine
;
Alpha1-adrenoceptors
;
Perfused rat kidney
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary 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 alpha1-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 alpha1-adrenoceptors. Thus, kynuramine lacks serotonin receptor agonist activity but possesses alphaI-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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00512065
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