Beta-adrenoceptor desensitization in a model of experimental asthma in guinea-pigs.
We investigated the possible occurrence of the desensitization of pulmonary beta-receptors in a model of experimental asthma such as the ovalbumin sensitized guinea-pig. Although some differences were observed between normal and asthmatic guinea-pigs, the desensitization procedure (isoproterenol (ISO) 10(-6) M x 20 min x 2) markedly impaired the relaxing capacity of ISO, epinephrine (EPI) and procaterol. With the beta 2 agonist procaterol, the sensitized tissues seemed to be more sensitive compared to normal. In parallel, the desensitization procedure produced a greater decrease in the relaxing capacity of procaterol in the sensitized tracheas. On the other hand, the two unselective beta-agonists (ISO and EPI) did not seem to discriminate between the two experimental conditions used. These data suggest that the immunological disturbance due to the active sensitization may induce a modification in beta-adrenoceptor reactivity. The results obtained with EPI after anaphylactic challenge are in agreement with this. In fact, the relaxing capacity of EPI was markedly reduced by antigen challenge.
Daffonchio
L
L
Institute of Pharmacological Sciences, University of Milan, Italy.
Abbracchio
M P
MP
Di Luca
M
M
Pasargiklian
R
R
Galli
P
P
Hernandez
A
A
Omini
C
C
D000318:Adrenergic beta-Agonists / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D001249:Asthma / Q000175:diagnosis / Q000188:drug therapy* / Q000276:immunology; D001985:Bronchial Provocation Tests; D003888:Desensitization, Immunologic; D004195:Disease Models, Animal; D006168:Guinea Pigs; D008297:Male
D000318:Adrenergic beta-Agonists