Protease inhibitor localization in control and streptozotocin-diabetic skeletal muscles.

alpha 1-Antitrypsin and alpha 1-inhibitor-3 were localized for the first time inside skeletal muscle cells. Their content, especially that of alpha 1-inhibitor-3, was greatly reduced following streptozotocin-induced diabetes. alpha 1-Antitrypsin and alpha 1-inhibitor-3 were also observed in the vascular components and interstitial space surrounding both control and diabetic soleus muscles as revealed by immunofluorescence. In diabetic muscles, the non-myofibre locale of alpha 1-inhibitor-3 was reduced, and to a lesser extent, alpha 1-antitrypsin. Both myofibre and extracellular patterns were reversed to control levels by insulin replacement.