A modified electrometric method for measurement of erythrocyte acetylcholinesterase activity in sheep.

A modified method was compared with an original electrometric method for measurement of erythrocyte acetylcholinesterase (EChE) activity in sheep. The mean +/- SD (pH/30 min) of EChE activity of 8 sheep measured by the modified procedure (0.70 +/- 0.15) was not significantly different from that of the original method (0.64 +/- 0.12). The inherently low plasma cholinesterase activity of the sheep as measured by the 2 methods were also not significantly different from each other (0.09 +/- 0.04 vs 0.10 +/- 0.04). The coefficient of variation of the modified method in measuring EChE activity was 8%. The method was used to demonstrate in vitro inhibition of sheep EChE activity by the organophosphorus and carbamate insecticides dichlorvos and methomyl, respectively. The method could be well-suited for rapid measurement of EChE activity in sheep, especially in cases of organophosphate and possibly carbamate poisoning.