Histochmical properties of myofiber types in thigh muscles of the chicken.

Abstract

The presence of subtypes of dark and light myofibers distinguished by myosin ATPase reaction after alkaline preincubaiton was studied in thigh muscles of chickens. The dark myofibers were subclassified into type II and SS, and the light myofibers into type I, SM and MM myofibers by the pH sensitivity of myosin ATPase. Type I myofibers reacted strongly for acid-stable ATPase and weakly for alkali-stable ATPase. Type II myofibers reacted negatively for acid-stable ATPase and strongly for alkali-stable ATPase. Type SM myofibers reacted strongly for acid-stable ATPase and moderately for alkali-stable ATPase. Type SS myofibers reacted strongly and type MM myofibers reacted moderately for both acid-stable and alkali-stable ATPase. Type II myofibers were subdivided into type IIA with strong activity for NADH:Nitro BT oxidoreductase (NADHOX) and type IIB with weak NADHOX activity. Type IIB myofibers were strong in activity for glycerol-3-phosphate:meandione oxidoreductase (GPOX) whereas many type IIA myofibers were weak. Type IIA myofibers were stained weaky to moderately with 3-hydroxybutyrate:NAD+ oxidoreductase (HBOX) an type IIB myofibers were stained very weakly. Type I, SM, SS and MM myofibers were stained strongly with NADHOX, weakly to moderately with HBOX and weakly with GPOX.