Nerve regulation of class I and class II-asymmetric forms of acetylcholinesterase in rat skeletal muscles.
Two classes of collagen-tailed, asymmetric forms (A-forms) of acetylcholinesterase (AChE) have been described in skeletal muscles of vertebrates. They are distinguished by their different solubilization requirements: class I A-forms are solubilized in the presence of high salt, whereas class II A-forms require in addition a chelating agent for solubilization. We report here that class II A-forms are less sensitive to nerve section than are class I A-forms. The latter form decreases faster and to a lower level of activity after denervation. The decay of both AChE classes is more rapidly in short-stump nerves than in long ones. The effect of nerve section on class II A-forms appears to be dependent on the particular muscle group being studied. Both classes of A-forms reappear after muscle reinnervation, but the class I A-forms recovered earlier. More interestingly, both classes of A-forms increase in normally innervated skeletal muscles after contralateral nerve injury. In this case, however, the class II A-forms change first. Muscular disuse induced by contralateral tenotomy is also followed by a rise in class II A-forms. Our results, showing differences in response and flexibility in the changes of the two classes of A-forms in several experimental conditions, represent a relevant contribution to the understanding of the regulation and functional role of the asymmetric forms of AChE in vertebrate skeletal muscles.
Fadić
R
R
Department of Cell and Molecular Biology, Faculty of Biological Sciences and Medicine, Catholic University of Chile, Santiago.
Inestrosa
N C
NC
D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D009045:Motor Endplate / Q000201:enzymology; D009121:Muscle Denervation; D009132:Muscles / Q000201:enzymology*; D010791:Phrenic Nerve / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D012584:Sciatic Nerve / Q000502:physiology*
D007527:Isoenzymes; D000110:Acetylcholinesterase