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STUDIES ON THE HYPOTENSIVE ACTION OF α‐METHYLDOPAMINE
Author(s) -
FINCH L.,
HERSOM A.,
HICKS P.
Publication year - 1975
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1975.tb07590.x
Subject(s) - chloralose , phentolamine , chemistry , haloperidol , medicine , adrenergic , dopamine , phenoxybenzamine , reticular formation , endocrinology , stimulation , pharmacology , propranolol , receptor
1 Intraventricular α‐methyldopamine (50–200 μg) produced a dose‐related fall in blood pressure in conscious spontaneously hypertensive rats. Pretreatment with intraventricular 6‐hydroxydopamine prevented this hypotensive effect of α‐methyldopamine. 2 The hypotensive effect of α‐methyldopamine was prevented by intraventricular injection of phentolamine or desmethylimipramine, but not by intraperitoneal injection of haloperidol. 3 Pretreatment with U‐14,624, a selective central dopamine‐β‐hydroxylase inhibitor, prevented the hypotensive effect of α‐methyldopamine. 4 α‐Methyldopamine was considerably less potent than noradrenaline as a pressor agent in the pithed rat, but noradrenaline and α‐methylnoradrenaline were found to be equipotent. 5 α‐Methyldopamine (1–5 mg i.c.v.) reduced pressor responses elicited by electrical stimulation of the mid brain reticular formation in cats anaesthetized with chloralose. 6 It is concluded that the hypotensive action of α‐methyldopamine in conscious animals involves intact central α‐adrenergic neurones and a central adrenergic uptake mechanism for the formation of α‐methylnoradrenaline.