Abstract
Cholinesterases and nonspecific esterases of normal and atrophic (denervated and tenotomized) adult rat gastrocnemius were assayed, the latter 5-45 days after operation. Acetylcholinesterase activity per whole muscle was about 25% of normal 5 days after denervation and, in permanently denervated animals, showed little change thereafter. Tenotomy caused a transient 27% fall. Butyrylcholinesterase was unaffected. Nonspecific esterase activity of denervated gastrocnemius (substrate, α-naphthyl acetate) was normal 30 days after reversible sciatic injury and 50% of normal 45 days after irreversible denervation. Wet weight and total protein fell in approximate parallel. Results of assay and electrophoresis (zymograms) showed that muscle esterase was mainly of B type, although A and C type acetylesterases accounted for about 10% of the free or soluble fraction. An increase in the free esterase activity of the homogenate and an absolute increase in A type esterase accompanied denervation and disuse. Bound esterase was 80% released by Triton X-100 and was entirely B type. Zymograms of neonatal muscle were distinguished by the prominence of A-esterases and the presence of an acetylcholinesterase which was not encountered in adults. Over-all, despite some points of similarity, zymograms of neonatal and atrophic adult muscles were distinctly different.