Development and optimization of reactivation techniques for carbamate-inhibited brain and plasma cholinesterases in birds and mammals.

Two biochemical assays were developed which promote and measure the induced reactivation of carbamate-inhibited cholinesterases in avian and mammalian brain and plasma samples. The effects of inhibitor concentration, temperature, and the extent of dilution on the achievement of a steady state equilibrium and the subsequent level and rate of recovery of brain cholinesterase activity were investigated. A similar procedure for reactivation of carbamate-inhibited plasma cholinesterase activity involved the removal of excess carbamate from a small sample volume (< 400 microliters). Both methods begin by measuring cholinesterase activity immediately following dilution and involve an incubation period during which conditions for spontaneous reactivation of the inhibited enzymes are maximized. Both assays are suitable for large-scale, rapid use and appear able to restore inhibited cholinesterase activity to levels closely approximating that of control values for each species tested. These methods will not only maximize the usefulness of cholinesterases in monitoring carbamate pesticide exposure but should prove to be extremely useful tools in the forensic assessment of carbamate exposure in human and wildlife pesticide incidents.