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(W/MF149) Plasma ChE activity in white stork (Ciconia ciconia) and sensitivity to anticholinesterase pesticides. Soler, Francisco1, González, Rosa1, Castellano, Antonio1, García-Rubio, Lourdes1, Míguez, Prado 1, García-Cambero, Pablo1, 1 ABSTRACT- Determination of cholinesterase activity is an economic and rapid tool widely known to diagnose exposure and intoxication by organophosphate and carbamate pesticides and has the advantage, in contrast with AChE brain determination, to achieve the sample without sacrifying the animal. The aim of this work is to establish the physiological values of plasma ChE activity in white stork (Ciconia ciconia), its variation according to age and to test the sensibility to different anticholinesterase pesticides. Total plasma ChE was determined discriminating between AChE and BChE by using a selective inhibitor: iso-OMPA. The evolution of total ChE levels of a group of nestling was controlled between 1st and 5th week of life. Pesticides used were dimetoathe (1-5 mg/ml), chlorpyrifos (0.1-5 mg/ml) and aldicarb (0.002-0.01 mg/ml). The inhibitory effect on plasma ChE activity was assayed at 0, 0.5, 1, 2, 4, 8 and 24 hours. Normal values of total plasma ChE were 1431±439 mU/mL, corresponding mainly to BChE (91%), and AChE represented only 9% of total. Plasma ChE did not suffer substantial variation regarding to age of nestling and remained similar to adults. Inhibition was dose.dependent and the concentrations that elicited inhibition next to 50% in 24 hours were as follows: aldicarb 0.0002 mg/ml, chlorpyrifos 0.1 mg/ml and dimethoate 1 mg/ml. The inhibitory potency was inversely related with DL50, since the more toxicity itself, the more inhibitory effect. ChE activity already declined at 15 min. for all the pesticides although the increase of inhibition was more constant for the aldicarb than for the organophosphates. Key words: cholinesterase, pesticides, white stork, poisoning |
