title: The dopamine receptors mediating inhibition of the sympathetic vasopressor outflow in pithed rats: pharmacological correlation with the D(2) -like type.
abstract: This study investigated in pithed rats whether dopamine can inhibit the sympathetic vasopressor outflow and analysed the pharmacological profile of the receptors involved. Male Wistar pithed rats were pre-treated with intravenous (i.v.) bolus injections of gallamine (25 mg/kg) and desipramine (50 μg/kg). The vasopressor responses to electrical stimulation of the sympathetic vasopressor outflow (0.03-3 Hz; 50 V and 2 msec.) were analysed before and during i.v. continuous infusions of the agonists dopamine (endogenous ligand), SKF-38393 (D(1) -like) or quinpirole (D(2) -like). If inhibition was produced by any agonist, then its capability to inhibit the vasopressor responses to i.v. bolus injections of exogenous noradrenaline (0.03-3 μg/kg) was also investigated. Dopamine (3-100 μg/kg min.) inhibited the vasopressor responses to both electrical stimulation and noradrenaline. In contrast, SKF-38393 (10-100 μg/kg min.) failed to inhibit the vasopressor responses to electrical stimulation; whereas quinpirole (0.1-30 μg/kg min.) inhibited the vasopressor responses to electrical stimulation but not those to noradrenaline. The sympatho-inhibition by quinpirole (1 μg/kg min.) remained unaltered after i.v. SCH 23390 (300 and 1000 μg/kg; D(1) -like receptor antagonist), but was abolished after i.v. raclopride (1000 μg/kg; D(2) -like receptor antagonist). These doses of antagonists did not modify per se the sympathetically-induced vasopressor responses. In conclusion, quinpirole-induced inhibition of the sympathetic vasopressor outflow is primarily mediated by activation of dopamine D(2) -like receptors.
authors: Departamento de Farmacobiología, Cinvestav-Coapa, Tlalpan, México DF.
authors: Guadalupe
authors: G
authors: Manrique-Maldonado
authors: Abimael
authors: A
authors: González-Hernández
authors: Bruno A
authors: BA
authors: Marichal-Cancino
authors: Ma Trinidad
authors: MT
authors: Villamil-Hernández
authors: Oscar Alcántara-Vázquez
authors: OA
authors: del Mercado
authors: David
authors: D
authors: Centurión
authors: Carlos M
authors: CM
authors: Villalón
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001808:Blood Vessels / Q000294:innervation; D003655:Decerebrate State; D018491:Dopamine Agonists / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology*; D004558:Electric Stimulation; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000378:metabolism* / Q000502:physiology; D017448:Receptors, Dopamine D2 / Q000378:metabolism* / Q000502:physiology; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000502:physiology; D014666:Vasomotor System / Q000187:drug effects / Q000502:physiology
chemical_list: D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2