Tissue acetylcholinesterase in plasma of chick embryos and dystrophic chickens

Abstract

The plasma cholinesterases of chickens (line 304) with inherited muscular dystrophy and 2 normal lines were examined from 12 days of incubation to 14 weeks after hatching. Acetylcholinesterase (AChE) and non-specific cholinesterase (BChE) activities were distinguished by spectrophotometric, electrophoretic and titrimetric analyses using acetylcholine, butyrylcholine, and their thioester analogs acetylthiocholine and butyrylthiocholine as substrates and 284C51 and iso-OMPA as selective inhibitors. Plasma from normal and dystrophic embryos and from dystrophic chicks had high AChE activity. For example, by 12 weeks of age, 37% of plasma acetylthiocholine hydrolysis was inhibited by the anti-AChE agent 284C51. The results support the view that embryo plasma contains AChE and BChE forms. After hatching the AChE forms decrease greatly in normal plasma and a shift in BChE forms occurs. Later, the AChE forms return in dystrophic line plasma. AChE activity in plasma was circumstantially associated with multiple molecular forms of AChE in the sarcoplasm of embryo and dystrophic muscles and it is likely that these muscles are sources of the plasma AChE activity. The results also confirmed that acetyl-β-methylcholine, unlike the situation which exists in mammals, is hydrolyzed by both AChE and BChE forms in the chicken, and cannot be used to distinguish these cholinesterases.