The lysosomal enzyme N-acetyl-beta-glucosaminidase in rabbit muscle following a period of ischaemia.

N-acetyl-beta-glucosaminidase activity increased in injured plantar muscle during the interval of 1 to 7 days after a period of 6 hours ischaemia of the rabbit hindpaw. Histochemical visualization demonstrated that this increased activity was not only associated with infiltrating inflammatory cells but also with the appearance of discrete lysosomal-like granules within damaged muscle fibres. Seven days after injury, the enzyme activity had reached a maximum with levels in the injured muscle 11 times higher than in normal muscle. The activity at this time was visualized in granules longitudinally arranged along regenerating muscle fibres, seemingly implicating the longitudinal sarcotubular system in their origin. Residual histochemical activity was evident at 14 and 28 days after injury. It is suggested that, in addition to its hydrolytic activity, N-acetyl-beta-glucosaminidase may have a role in the formation of mucopolysaccharides in the regenerative processes of muscle.