Failure of enhancement by labetalol of bronchopulmonary effects of histamine in guinea-pigs: independence of alpha-adrenoceptor antagonism.
Br J Pharmacol
; 91(3): 487-92, 1987 Jul.
Article
em En
| MEDLINE
| ID: mdl-2886173
ABSTRACT
The effect of labetalol on histamine-induced bronchoconstriction was studied in anaesthetized guinea-pigs. Unlike propranolol (1 mg kg-1), the same dose of labetalol did not enhance histamine-induced bronchoconstriction. To determine whether the absence of enhancement of the respiratory effects of histamine by labetalol was due to its alpha 1-blocking properties or to its partial agonist activity at beta 2-adrenoceptors, the effects of propranolol plus prazosin and of propranolol plus labetalol on histamine-induced bronchoconstriction were examined. In both cases, the bronchoconstrictor effects of histamine were enhanced to the same extent as with propranolol alone. These data support the hypothesis that the non impairment of respiratory mechanics by labetalol is not due to antagonism at alpha-adrenoceptors and may be mediated by its partial agonist activity at beta 2-adrenoceptors.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Propranolol
/
Respiração
/
Histamina
/
Antagonistas Adrenérgicos alfa
/
Labetalol
Limite:
Animals
Idioma:
En
Revista:
Br J Pharmacol
Ano de publicação:
1987
Tipo de documento:
Article