[The activity of blood cholinesterase in rats exposed to dimehypo].
OBJECTIVE
To determine whether and to what degree the activity of cholinesterase(ChE) is inhibited by dimehypo at different doses of dimehypo [scientific name: 2-dimethylamine-1,3-bi(sodium hyposulfit)].


METHODS
Rats were dosed with dimehypo or methamidophos orally, and were randomly divided into four subgroups according to the pesticide doses, which were 1/16, 1/8, 1/4 and 1/2 of LD50 respectively(the LD50 of dimethypo and methamidophos is 342 mg/kg and 20 mg/kg respectively). The activity of ChE in blood was determined before and 30 min, 1, 2, 4 and 24 h after exposure. The modified Ellman Method was employed to measure the activity of ChE.


RESULTS
1/16 LD50 dose of dimehypo did not affect the activity of ChE. When the dose increased, the activity of ChE decreased accordingly. 1/2 LD50 dose of dimehypo inhibited the activity of ChE by 35.9% compared with that of control group(P < 0.01). In rats dosed with methamidophos, even 1/16 LD50 dose inhibited the activity of ChE by 42.4% compared with that of control group. When the dose of methamidophos increased, the activity of ChE decreased accordingly. 1/2 LD50 dose of methamidophos inhibited the activity of ChE by 52.9%. The activity of ChE in the rats dosed with dimehypo at various doses was significantly lower than that in the rats dosed with corresponding doses of methamidophos(P < 0.01).


CONCLUSIONS
Higher doses of dimehypo may inhibit the activity of ChE. However, as compared with methamidophos, dimehypo is a weaker inhibitor of ChE.
Wan
Weiguo
W
Occupational Department, Huashan Hospital, Fudan University, Shanghai 200040, China.
Xu
Mailing
M
Zou
Hejian
H
Lu
Ailing
A
Shen
Xinyu
X
Chen
Yuming
Y
D000818:Animals; D002800:Cholinesterase Inhibitors / Q000633:toxicity*; D002802:Cholinesterases / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D007306:Insecticides / Q000633:toxicity*; D007928:Lethal Dose 50; D009946:Organothiophosphorus Compounds / Q000633:toxicity; D051381:Rats
D002800:Cholinesterase Inhibitors; D007306:Insecticides; D009946:Organothiophosphorus Compounds; C014655:methamidophos; D002802:Cholinesterases