An analysis of the alpha-adrenoceptor modulation of vasomotor tone at the level of lateral medullary pressor area (LMPA).
Naunyn Schmiedebergs Arch Pharmacol
; 330(3): 163-8, 1985 Sep.
Article
en En
| MEDLINE
| ID: mdl-2865682
ABSTRACT
Microinjection of noradrenaline and clonidine into lateral medullary pressor area (LMPA) of chloralose anaesthetized cats produced dose dependent decrease in blood pressure without affecting heart rate, while phenylephrine did not elicit any cardiovascular response. Selective alpha 2-adrenoceptor antagonists idazoxan and piperoxan, microinjected locally, blocked the effects of the agonists but prazosin and phenoxybenzamine, which are relatively selective for alpha 1-adrenoceptors, failed to do so. Clonidine did not elicit any response in guanethidine pretreated cats but noradrenaline microinjected into LMPA of these animals induced a pressor response which was blocked by prazosin pretreatment. It is concluded that catecholaminergic fibres impinging upon this area inhibit the activity of the inhibitory second order baroreceptor neurone by activating alpha 1-adrenoceptors while alpha 2-adrenoceptors situated presynaptically on these inhibitory catecholaminergic nerve terminals are responsible for the manifestation of the hypotensive effect of clonidine and exogenously administered noradrenaline.
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Bases de datos:
MEDLINE
Asunto principal:
Presión Sanguínea
/
Receptores Adrenérgicos alfa
/
Área Hipotalámica Lateral
/
Músculo Liso Vascular
Límite:
Animals
Idioma:
En
Revista:
Naunyn Schmiedebergs Arch Pharmacol
Año:
1985
Tipo del documento:
Article