In order to study the threshold concentrations of isocyanates (IC) for induction of lung disorders, constrictive responses of tracheal smooth muscles to acetylcholine (ACH) in guinea pigs with and without diisocyanate [toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI) and diphenylmethane diisocyanate (MDI) ] exposure were investigated.
An IC-induced increase in smooth muscle responsiveness was studied by measuring cumulative ACH dose responses (10-10 to 10-4 M ACH).
Basal ACH dose-response curves, measured twice in intervals of 1 h using tracheal preparations of 11 guinea pigs previously not exposed to IC, were reproducible.
Subchronic in vivo exposures to TDI, HDI, and MDI atmospheres of 10 and 20 parts per billion (ppb) on 5 consecutive days led to significantly (p<0.05) increased ACH responsiveness of tracheal smooth muscle, whereas concentrations of 2.5 and 5 ppb were not effective.
Exposure to HDI atmospheres of 10 ppb for 1,2,4, or 8 weeks resulted in a time-dependent increase in ACH responses (p<0.05) of guinea pig tracheal smooth muscle.
Increased tracheal muscle responses to ACH were transient since tracheal preparations from animals exposed to 10 and 20 ppb MDI for 4 weeks and with an exposure-free interval of 8 weeks before preparation did not show enlarged ACH responses, which were present in preparations at the end of the exposure period (p<0.05). (...)
Mots-clés Pascal : Diisocyanate organique, Exposition professionnelle, Maladie professionnelle, Hyperréactivité, Voie respiratoire, Acétylcholine, Muscle lisse, Trachée, Pathogénie, Cobaye, Rodentia, Mammalia, Vertebrata, Animal, Médecine travail
Mots-clés Pascal anglais : Organic diisocyanate, Occupational exposure, Occupational disease, Hyperreactivity, Respiratory tract, Acetylcholine, Smooth muscle, Trachea, Pathogenesis, Guinea pig, Rodentia, Mammalia, Vertebrata, Animal, Occupational medicine
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 99-0239543
Code Inist : 002B30B01A. Création : 16/11/1999.