title: Influence of intrinsic sympathomimetic activity (ISA) during beta-adrenoceptor blockade in asthmatics.
abstract: 1 Ten patients suffering from extrinsic bronchial asthma were examined. 2 In the pretreatment period, the histamine concentration required to produce a 20% decrease of forced expiratory volume in one second (FEV1) was 7.71 mg/ml. 3 Histamine provocation was repeated 2 h after administration of placebo, propranolol 40 mg, pindolol 5 mg or metoprolol 50 mg. After pindolol and metoprolol the histamine concentrations were slightly, but not significantly, lower than after placebo. After propranolol only 3.16 mg/ml histamine was necessary to reduce FEV1 by 20%. 4 This indicates that in equipotent cardiac beta-adrenoceptor blocking doses, in contrast to propranolol, neither pindolol nor metoprolol increased sensitivity to the bronchoconstrictor effects of inhaled histamine.
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000009:adverse effects*; D000328:Adult; D000368:Aged; D001249:Asthma / Q000503:physiopathology*; D005260:Female; D005541:Forced Expiratory Volume; D006632:Histamine / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D013566:Sympathomimetics / Q000009:adverse effects*
chemical_list: D000319:Adrenergic beta-Antagonists; D013566:Sympathomimetics; D006632:Histamine