The ATPase stain results in muscle fibers showing different staining patterns based on their enzymatic activity:
- Type I fibers (slow-twitch) typically show dark staining at an acidic pH (pH 4.3) and light staining at an alkaline pH (pH 9.4). - Type II fibers (fast-twitch) show light staining at an acidic pH and dark staining at an alkaline pH.
These patterns are due to the intrinsic differences in the myosin ATPase activity between the fiber types.
