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Effect of bromocriptine on neurogenic vasoconstriction in the isolated autoperfused hindquarters of the rat
Author(s) -
Roquebert J.,
Alaoui K.,
Morán A.
Publication year - 1990
Publication title -
fundamental and clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.655
H-Index - 73
eISSN - 1472-8206
pISSN - 0767-3981
DOI - 10.1111/j.1472-8206.1990.tb00038.x
Subject(s) - pergolide , yohimbine , bromocriptine , apomorphine , endocrinology , sulpiride , methysergide , medicine , stimulation , agonist , domperidone , metergoline , dopamine agonist , dopamine receptor , antagonist , dopamine , dopaminergic , prolactin , serotonin , receptor , serotonergic , hormone
Summary— The effects of local administration of bromocriptine were studied in the isolated autoperfused hindquarters of the rat, and compared to the actions of apomorphine and pergolide. Local injection of bromocriptine (1 μg kg −1 ) (into the hindquarters) did not alter perfusion pressure, but reduced the pressor response to electrical stimulation of the lumbar sympathetic chains at all frequencies used (0.5–10 Hz;5 ms;35 V). Bromocriptine (1 μg kg −1 ) did not alter the increases in perfusion pressure induced by local administration of noradrenaline. The effects of local administration of apomorphine (1 μg kg −1 ) and pergolide (1 μg kg −1 ) were similar to that of bromocriptine. The inhibitory effect by bromocriptine, apomorphine and pergolide of the stimulation‐evoked pressor responses was completely antagonized by intravenous administration of the dopamine receptor antagonist sulpiride (0.3 mg kg −1 ) but was not by the α 2 ‐adrenoceptor antagonist yohimbine (1 mg kg −1 ). In this dose, yohimbine antagonized the inhibitory effect of the α‐adrenoceptor agonist clonidine (1 μg kg −1 ). The inhibitory effect of clonidine was not altered by sulpiride but was antagonized by yohimbine. The results indicate that bromocriptine like apomorphine and pergolide inhibit neurally‐induced pressor responses in the autoperfused hindquarters of the rat by stimulation of presynaptic dopamine receptors. Stimulation of these receptors leading to a fall in noradrenaline release and consequently of vasomotor tone, might at least in part explain the vasodilatator effects of bromocriptine in the rat.