COMPARISON OF RESPIRATORY AND CARDIOVASCULAR EFFECTS OF ISOPROTERENOL, PROPRANOLOL, AND PRACTOLOL IN ASTHMATIC AND NORMAL SUBJECTS

[摘要] Pulmonary functions, by means of FEV1, [forced expiratory vol in 1 s), FVC [forced vital capacity] airway resistance and cardiovascular responses, i.e., ECG, blood pressure and pulse contour, were measured in 10 control and 15 symptom-free asthmatic subjects during and after isoproterenol infusions, with or without previous administration of propranolol or practolol. Bronchial methacholine sensitivity and response to isoproterenol after methacholine were also measured. Bronchial methacholine sensitivity challenge was markedly enhanced by propranolol and the effect of isoproterenol infusion on the pulmonary function was also significantly diminished. Practolol did not reveal any effect on bronchial sensitivity to methacholine or isoproterenol. The above changes were much more profound in symptom-free asthmatic subjects than in control subjects. The results suggest that practolol does not significantly affect the .beta.-2 bronchial receptors, is safe to use in asthmatic subjects, and is consistent with an abnormality of these receptors in bronchial asthma.