Tissue acetylcholinesterase in plasma of chick embryos and dystrophic chickens.

Specific acetylcholinesterases (ACHE) are found in neural and muscle tissues of mammals and birds and in the red blood cells of many mammals. They differ in many respects from the non-specific cholinesterases (BChE) in plasma and elsewhere in the body (Augustinsson 1963). One major distinction (amongst others) is that AChE enzymes hydrolyze acetylcholine more rapidly than other choline esters ; BChE enzymes rapidly hydrolyze butyrylcholine and similar choline esters in addition to acetylcholine. One similarity is that both AChE and BChE enzymes exist as multiple molecular forms. Previous work from this laboratory (Wilson, Montgomery and Asmundson 1968 ; Wilson, Mettler and Asmundson 1969; Wilson, Kaplan, Merhoff and Mori 1970; Wilson, Schenkel and Fry 1971) showed that specific isozymes of AChE are associated with enzyme activity outside the motor end-plates in the cytoplasm of developing muscles of the chicken. Although their activity disappears after hatching in normal twitch muscles, they are present in denervated muscles and fast twitch muscles from genetically dystrophic and Vitamin E-deficient chickens, situations in which there is evidence that normal nerve-muscle relationships are interrupted (Holliday, Van Meter, Julian and Asmundson 1965b; Guth 1968; Albuquerque and Warnick 1971 ; Wilson et al. 1971 ; Wilson and Viola 1972). Total cholinesterase activity is also enhanced in these conditions (Wilson et al. 1970). For example, the activity of genetically dystrophic muscle can be as much as 40-fold (on a wet weight basis) that of its normal counterpart. During experiments on the regulation of AChE isozymes in cultured chick embryo muscle, evidence was obtained showing that these AChE forms were released in quan-