Selectivity of the Intrinsic Sympathomimetic Activity of the β-Adrenergic Blocking Drug Bucindolol
Autor: | Nilda M. Munoz, Michel Cavigelli, Alan R. Leff, Edward R. Garrity, J. Tallet, Sol I. Rajfer, David Deitchman |
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Rok vydání: | 1984 |
Předmět: |
Male
Chronotropic Agonist medicine.medical_specialty Contraction (grammar) medicine.drug_class Adrenergic beta-Antagonists Blood Pressure Bronchi Propranolol Propanolamines Norepinephrine chemistry.chemical_compound Dogs Heart Rate Internal medicine Animals Medicine Sympathomimetics Pharmacology biology business.industry Fissipedia Isoproterenol Bucindolol biology.organism_classification Trachea Blood pressure Endocrinology chemistry Circulatory system Female Cardiology and Cardiovascular Medicine business Muscle Contraction medicine.drug |
Zdroj: | Journal of Cardiovascular Pharmacology. 6:859-866 |
ISSN: | 0160-2446 |
DOI: | 10.1097/00005344-198409000-00019 |
Popis: | We studied the comparative effects of beta-adrenergic blockade with propranolol (PROP) and bucindolol (BUC), a beta-adrenergic agonist having both alpha-adrenergic blocking properties and intrinsic sympathomimetic activity (ISA) on airway and cardiovascular responses, in 38 mongrel dogs in situ. Intravenous infusion of 0.6 mg/kg + 6 micrograms/kg/min BUC and 2.0 mg/kg + 20 micrograms/kg/min PROP caused identical shifts in the isoproterenol (ISO) EC50 for chronotropic and hypotensive arterial blood pressure responses. After PROP administration, resting heart rate (HR) decreased from 188 +/- 15 to 142 +/- 12 beats/min (p less than 0.02); BUC caused no decrease in HR. In contrast, the effects of BUC and PROP on mean arterial blood pressure response to ISO were similar. No change in bronchomotor tone was observed after bolus injection of either BUC or PROP. Beta-Adrenergic relaxation to ISO and alpha-adrenergic contraction to norepinephrine (NE) were studied simultaneously in tracheal and bronchial airways using chronotropically equivalent beta-adrenoceptor blocking doses of PROP and BUC. Comparable inhibition of ISO-induced airway relaxation after contraction with 120 micrograms/kg/min i.v. serotonin was demonstrated in both PROP (n = 5) and BUC (n = 5) groups (p less than 0.01 for doses greater than 5 X 10(-11) mol/kg). Similarly, both BUC (n = 5) and PROP (n = 5) blocked beta-adrenergic relaxation and caused identical alpha-adrenergic airway contraction to intravenous NE. We conclude that the ISA of the beta-adrenergic blocking drug BUC can be demonstrated on the spontaneous rate of the heart but not on the activity of bronchial smooth muscle. BUC neither augments ISO-induced relaxation nor inhibits NE-induced contraction of airways after effective chronotropic blockade. |
Databáze: | OpenAIRE |
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