[Recovery of the acetylcholinesterase activity in a monolayer culture of chick myoblasts after irreversible inhibition by an organophosphorus inhibitor].

The recovery of the acetylcholine esterase (AChE) activity after the irreversible inhibition with an organophosphorus inhibitor B-156 was studied in a developing monolayer culture of chick myoblasts. The culture was obtained from muscles of posterior limbs of the 11 day old chick embryos. The AChE activity was estimated by the modified Ellman method from the moment of inoculation to the stage of spontaneous contractions of muscle fibres. After the B-156 treatment the AChE activity of muscle cells decreased, then started to increase and the maximum recovery of activity, below the initial level, was attained within roughly 2 days after the treatment. The AChE activity in the treated culture somewhat decreased thereafter. The lower the inhibitor concentration, i.e. the lower the value of the initial AChE inhibition, the higher the starting rate and degree of recovery of the AChE activity. The results obtained suggest that, unlike the multilayer culture of muscle tissue at later stages of differentiation no compensatory enhancement of AChE biosynthesis after irreversible inhibition of this enzyme by an organophosphorus inhibitor is observed in the monolayer culture of chick myoblasts at the early stages of myogenesis.