Characterization of acetylcholinesterase molecular forms in slow and fast muscle of rat

Abstract

Multiple molecular forms of acetylcholinesterase (AChE EC 3.1.1.7) from fast and slow muscle of rat were examined by velocity sedimentation. The fast extensor digitorum longus muscle (EDL) hydrolyzed acetylcholine at a rate of 110 mumol/g wet weight/hr and possessed three molecular forms with apparent sedimentation coefficients of 4S, 10S, and 16S which contribute about 50, 35, and 15% of the AChE activity. The slow soleus muscle hydrolyzed acetylcholine at a rate of 55 mumol/g wet weight/hr and has a 4S, 10S, 12S, and 16S form which contribute 22, 18, 34, and 26% of AChE activity, respectively. A single band of AChE activity was observed when a 1M NaCl extract with CsCl (0.38 g/ml) was centrifuged to equilibrium. Peak AChE activity from EDL and SOL extracts were found at 1.29 g/ml. Resedimentation of peak activity from CsCl gradients resulted in all molecular forms previously found in both muscles. Addition of a protease inhibitor phenylmethylsulfonyl chloride did not change the pattern of distribution. The 4S form of both muscles was extracted with low ionic strength buffer while the 10S, 12S, and 16S forms required high ionic strength and detergent for efficient solubilization. All molecular forms of both muscles have an apparent Km of 2 x 10(-4) M, showed substrate inhibition, and were inhibited by BW284C51, a specific inhibitor of AChE. The difference between these muscles in regards to their AChE activity, as well as in the proportional distribution of molecular forms, may be correlated with sites of localization and differences in the contractile activity of these muscles.

Inflammatory response during slow- and fast-twitch muscle regeneration

“…Previous studies showed that denervation leads to a decrease in AChE activity, which then is resurrected during the reinervation stage. [50][51][52] Some data also suggest that this activity is homogenously present within muscle fibers regardless of the stage of regeneration. 53,54 However, in our study, we found that the activity of AChE, was localized predominantly within the fiber membranes.…”

“…The localization of AChE activity, which is a crucial component of the neuromuscular junction responsible for degradation of the neurotransmitter acetylcholine, was analyzed by the Karnovsky‐Roots method. Previous studies showed that denervation leads to a decrease in AChE activity, which then is resurrected during the reinervation stage …”

Regulation by exercise of the pool of G4 acetylcholinesterase characterizing fast muscles: opposite effect of running training in antagonist muscles

“…A series of studies recently performed in rodents (rat, mouse, and rabbit) has revealed that G, is closely related to the dynamic state ofthe skeletal muscle. Indeed, whereas slow-twitch muscles contain only a minimal amount of tetramer, fast muscles characteristically exhibit high levels ofG, (Bacou et al, 1982;Gisiger and Stephens, 1982Groswald and Dettbam, 1983). Furthermore, according to a recent report (Gisiger and Stephens, 1988) this additional pool is concentrated at the perijunctional sarcoplasmic reticulum, where it forms a cojunctional compartment embedding the neuromuscular junctions in an AChE-rich environment.…”

Molecular Forms of Acetylcholinesterase and Butyrylcholinesterase in the Aged Human Central Nervous System

“…Although the significance of the different molecular forms remains unclear, their tissue-specific distributions are thought to reflect the physiological functions of the different tissues (Massoulie and Bon, 1982). For example, different distributions of AChE molecular forms have been reported to be correlated with the contractile activity of slow and fast rat muscle (Gisiger and Stephens, 1983;Groswald and Dettbarn, 1983;Lgmo et al, 1985).…”