ABSTRACT
OBJECTIVE: To study the process and significance of the distribution of free organophosphorus poisons (FOPs) in the blood and bile of rabbits poisoned with organophosphates. METHODS: Seventy two livid blue rabbits, male, 2 - 2.5 kg in weight, were divided into 3 groups: trichlorfon (556.0 mg/kg), monocrotophos (11.12 mg/kg) and methyl parathion (37.05 mg/kg). Each group consisted of 24 rabbits. All organophosphates were administered by subcutaneous route. Blood and bile were collected at time intervals of 1, 6, 24, 96 hours after administration. Blood cells and plasma were separated. Acetylcholinesterase (AChE) activity was measured with dithiobisnitrobenzoic acid (DTNB) enzyme kinetic method. The levels of FOPs in plasma and bile were determined with enzyme inhibited method. RESULTS: From 1 h to 96 h after administration negative correlation was found between time and FOP concentration in plasma (trichlorfon, r = -0.74, P < 0.01; monocrotophos, r = -0.55, P < 0.01; methyl parathion, r = -0.69, P < 0.01), and it was also found in bile between time and FOP concentration of trichlorfon (r = -0.97, P < 0.01) and monocrotophos (r = -0.71, P < 0.01). There is no linear correlation between time and concentration of methyl parathion in bile (r = -0.14, P > 0.05). When FOPs in plasma were not detectable at 96 h after administration, high levels of FOPs could still be detected in bile [trichlorfon (300.3 +/- 174.44) IU/L; monocrotophos (362.8 +/- 136.62) IU/L; methyl parathion (101.0 +/- 75.85) IU/L]. CONCLUSION: The bile is the most important store for FOPs in animal. FOPs can exist in bile over 96 h. The process of poisoning is a changing process of absorption, distribution and redistribution and it is different owing to various physical and chemical properties of organophosphates.
