Effects of inhaled cholinesterase inhibitors on bronchial tonus and on plasma and erythrocyte acetylcholine esterase activity in rats.
Young adult male and female Wistar rats were inhalationally exposed head-only for 1 or 4 h to different anticholinesterase aerosols. The compounds tested were dichlorvos, fenamiphos, methamidophos, parathion, a pyrimidine thiophosphate and the carbamate propoxur. These compounds are direct or indirect inhibitors of cholinesterase activity. Immediately after termination of exposure to the compounds, the rats were anesthetized with barbiturate and subjected to pulmonary function tests. An acetylcholine provocation test was performed to correlate the effect of the cholinesterase inhibition and lung resistance. The results basically revealed that by inhalation exposure bronchoconstriction in the absence of acetylcholine provocation did not occur at toxicologically significant doses of the pesticides. An increase in lung resistance was observed only after provocation. However, measurements of plasma cholinesterase activity proved to be more sensitive than the provocation test. With regard to their diagnostic value, the results of the reported study may be summarized as follows (beginning with the most sensitive parameter): plasma cholinesterase activity depression greater than or equal to acetylcholine-induced bronchoconstriction greater than or equal to cholinergic symptoms greater than erythrocyte cholinesterase activity depression greater than pulmonary resistance without acetylcholine provocation.
Pauluhn
J
J
Department of Toxicology, BAYER AG, Wuppertal, F.R.G.
Machemer
L
L
Kimmerle
G
G
D000110:Acetylcholinesterase / Q000097:blood / Q000378:metabolism*; D000280:Administration, Inhalation; D000336:Aerosols; D000818:Animals; D001980:Bronchi / Q000187:drug effects*; D001985:Bronchial Provocation Tests; D002800:Cholinesterase Inhibitors / Q000633:toxicity*; D004006:Dichlorvos / Q000633:toxicity; D005260:Female; D008297:Male; D009943:Organophosphorus Compounds / Q000633:toxicity; D010278:Parathion / Q000633:toxicity; D001074:Propoxur / Q000633:toxicity; D051381:Rats; D011919:Rats, Inbred Strains; D012129:Respiratory Function Tests
D000336:Aerosols; D002800:Cholinesterase Inhibitors; D009943:Organophosphorus Compounds; D010278:Parathion; D004006:Dichlorvos; D001074:Propoxur; D000110:Acetylcholinesterase; C002698:fenamiphos