Interaction between fenoterol, ipratropium, and acetylcholine on human isolated bronchus.
Functional antagonism between fenoterol (F) and acetylcholine (ACh) and interaction between F and ipratropium (Ipr) on ACh-induced contraction were evaluated on isolated human bronchi. In the presence of increasing concentrations of ACh (2 X 10(-4) and 2 X 10(-3) mol/L), dose-response curves of the relaxant effect of F were shifted to the right (0.45 and 0.92 log units), and the maximal effect of F, expressed as a percentage of the effect of theophylline, 3 X 10(-3) mol/L, was reduced from control values of 92.1 +/- 4% to 70.8 +/- 7.0%, and to 67.2 +/- 7.1%, according to the functional antagonism. In the presence of Ipr, 10(-9) and 10(-8) mol/L, the functional antagonism between ACh and F was partially reversed. Concentration response-curves to F versus ACh, 2 X 10(-3) mol/L, were shifted to the left, and although the -log molar concentration producing 50% of maximal effect was not significantly modified, the maximal effect of F was significantly increased in the presence of Ipr, 10(-8) mol/L. It is concluded that the effect of combined F and Ipr on the isolated human bronchus contracted with ACh appears to be of the additive type.
Advenier
C
C
Laboratoire de Pharmacologie, Faculté de Médecine Paris-Ouest, France.
Naline
E
E
Matran
R
R
Toty
L
L
Bakdach
H
H
D000109:Acetylcholine / Q000494:pharmacology*; D001286:Atropine Derivatives / Q000494:pharmacology*; D001980:Bronchi / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005280:Fenoterol / Q000494:pharmacology*; D006801:Humans; D009241:Ipratropium / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects
D001286:Atropine Derivatives; D005280:Fenoterol; D009241:Ipratropium; D000109:Acetylcholine