Choline acetyltransferase and cholinesterase activities in muscle of dystrophic mice

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Abstract
Quantitative measurements of choline acetyltransferase (ChAc) and cholinesterase (ChE) activities, using either acetylthiocholine (AcSCh) or butyrylthiocholine(BuSCh) as substrates, have been made in the sole plate and nonsole plate regions of sternomastoid muscles of normal and dystrophic mice. Serial adjacent sections of frozen, unfixed muscle were analyzed with microchemical methods for enzyme activities. The number of sole plates per section was estimated from the histochemical staining method (lead-thiolacetic acid) for ChE. Both ChAc and ChE (substrate, AcSCh) activities were concentrated in the sole plate region, although a significant portion of both enzymes was present in muscle fibers (i.e., nonsole plate regions). In dystrophic muscle ChAc activity was only slightly less than normal in both these regions; ChE activity was slightly reduced in the muscle fibers but markedly reduced in the sole plate region. Lowered ChE activity at the sole plate could account for many of the abnormal pharmacological and physiological characteristics of dystrophic muscle. ChE (substrate, BuSCh) activity was found all along the length of the muscle, but there was no correlation of enzyme activity with the sole plate region; in dystrophic muscle this activity was slightly lower than normal.