Acetylcholine-Cholinesterase Relationships in Embryonic Chick Lung Cultivated in vitro ∗

Summary

Addition of 0.02 Molar acetylcholine to the medium of 15-day embryo chick lung cultivated in vitro for 8 days caused a 2- to 6-fold increase in the cholinesterase activity of that tissue. The increase in enzyme activity was maximal 4 days after addition of acetylcholine to the medium, and was maintained only by the continued addition of acetylcholine to the medium. Neither choline nor acetate alone nor choline and acetate together produced an increase in enzyme activity comparable to that produced by acetylcholine. Results of substrate specificity studies on the cholinesterases of chick embryo lung suggested that there was both an acetylcholinesterase and a non-specific esterase in the lung cells. Only the acetylcholinesterase was affected by the added acetylcholine. The results indicated that acetylcholine was an inducing agent for the formation of acetylcholinesterase in the embryo chick lung cells cultivated in vitro.