Beta-adrenoceptors in vascular capacitance responses to unloading of carotid baroreceptors in anesthetized dogs.
Am J Physiol
; 273(4): H1713-8, 1997 10.
Article
em En
| MEDLINE
| ID: mdl-9362235
ABSTRACT
The role of beta- and alpha-adrenoceptors in the total vascular capacitance responses to changing pressure in vascularly isolated carotid sinuses of anesthetized and atropinized dogs was investigated. A change in vascular capacitance was determined by measuring the shift of blood in and out of a reservoir that was connected to the aorta and maintained at a constant pressure. Changes in carotid sinus pressure from 135 to 57 mmHg and back to 137 mmHg resulted in a rapid vascular capacitance response of approximately 30 ml in the absence of adrenoceptor antagonists. Administration of a beta2-adrenoceptor antagonist (ICI-118551) caused a significant enhancement of the capacitance responses to similar decreases and increases in carotid sinus pressure (approximately 130%). Administration of a beta1-adrenoceptor antagonist (CGP-20712A) did not cause any further enhancement of the responses. However, an alpha-blocker (phentolamine) reduced the responses by 75%. The results suggest that in the presence of a beta2-adrenoceptor antagonist vascular capacitance responses to loading and unloading of baroreceptors are greatly enhanced and that patients suffering from orthostatic syncope may benefit from this kind of drug.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Pressorreceptores
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Artérias Carótidas
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Receptores Adrenérgicos beta
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Capacitância Vascular
Limite:
Animals
Idioma:
En
Revista:
Am J Physiol
Ano de publicação:
1997
Tipo de documento:
Article