The effects and site of action of a-adrenergic blocker (E-643) were studied in patients with bronchial asthma who hardly responded to β2-receptor stimulants and xanthines. Spirometry, air-or He-O2- flow volume curves, respiratory resistance, closing volume and arterial blood gas analysis were examined before and after oral administration of E-643 alone, inhalation of orciprenaline with premedication of E-643 and inhalation of PGF2α with premedication of E-643, respectively. In our studies, we found that 1) E-643 resulted in decrease of bronchoconstriction moderately but significantly. 2) E-643 increases the bronchodilator effect of orciprenaline. 3) E-643 inhabits the bronchoconstrictor effect of PGF2α 4) The bronchoditator effect of E-643 acts not only on large airways but peripheral airways.
We concluded that α1-adrenergic blocker enhances the treatment of bronchial asthma, especially in patients who benifit little from β2-receptor stimulants and xanthines.
