Histochemistry of some acid hydrolases in striated muscles of the rat

The distribution of acid phosphatase, beta-N-acetylglucosaminidase, beta-glucuronidase, and acid beta-galactosidase was studied in mm. extensor digitorum longus, soleus, and diaphragm of rats. Using the technic of semipermeable membranes activities of these enzymes were demonstrated beside cells of the interstitial tissue in muscle fibers themselves as well. Acid phosphatase displayed the highest activity which appeared in many small dots dispersed in the fiber. The activity of acid phosphatase was about 1.2 X higher in the m. soleus than in the m. extensor digitorum longus. In the latter muscle a somewhat higher activity was often found in muscle fibers displaying a higher staining for NADH tetrazolium reductase. The activity of beta-N-acetylglucosaminidase was slightly lower, that of beta-glucuronidase very weak but still discernible. The activity of acid beta-galactosidase was not ascertained in the majority of fibers. The ratio of activities measured in an area of the same size in cells of the interstitial tissue and in muscle fibers amounted in average to 2.6:1 in the case of acid phosphatase, 2.5:1 in the case of beta-N-acetylglucosaminidase, 5.7:1 in the case of beta-glucuronidase, and 44.3:1 in the case of acid beta-galactosidase. The importance of the histochemical technic in studies concerned with acid hydrolases in striated muscle fibers in normal and pathological conditions is pointed out.