Visualization of collagenase-sensitive acetylcholinesterase in isolated cardiomyocytes and in heart tissue.

Previous studies have indicated that the asymmetric form of acetylcholinesterase (collagen-tailed) is localized in the basal lamina of the neuromuscular junction of skeletal muscle. The present study shows localization of the asymmetric acetylcholinesterase in the heart of the rat. Antiserum to 14 + 18 S acetylcholinesterase of the electric eel was raised in rabbits. The purified antibody did not react with collagen type I or laminin. Collagenase reduced the immunoreactivity of the enzyme with the purified antibody. Isolated cardiomyocytes and frozen sections of the heart were stained for acetylcholinesterase with the antibody. Diffuse immunofluorescence appeared over the surface of the cardiomyocytes. In the frozen sections, the immunofluorescence was most intense at the cell boundaries. These data suggest that collagenase-sensitive acetylcholinesterase in the heart is present in the myocytes and occurs in the vicinity of the basal lamina.