Calcium-activated neutral protease and its endogenous inhibitor in tissues of dystrophic and normal mice.

Calcium-activated neutral protease (milli-CANP) and its endogenous inhibitor are elevated in muscle tissues, primarily the skeletal muscle and heart, of dystrophic mice (C57BL/6J dy/dy) as compared to the control strain (C57BL/10J). Tissues showing relative increase of CANP also show significant loss of enzymes such as CK, LDH in comparison to plasma, where these enzymes register a significant increase. PK is lost minimally from these tissues, probably showing a "sparing effect." Absence of any significant change in CANP activity in the liver points to a specific role of CANP in the dystrophic process. In the skeletal muscle the endogenous CANP inhibitor registers a concomitant increase with CANP without altering the enzyme/inhibitor ratio.