Composition and distribution of muscle fiber types in the rat gastrocnemius muscle / 重庆医科大学学报

ABSTRACT

Objective:To study the composition and distribution of two muscle fiber types in SD rat gastrocnemius muscle in order to learn its function.Methods:Gastrocnemius muscles of both sides of hind limbs were collected from 10 adult SD rats.8-?m-thick cryostat sections were transected and then stained with the method of myosin-ATPase following a procesure modified partially from one that Guth & Samaha reported before.Results:Gastrocnemius muscle from SD rats can be clearly identified with two different fiber types which are typeⅠ(slow twitch fiber)and typeⅡ(fast twitch fiber) by the myosin-ATPase staining method.Fibers of type I are stained white while fibers of type II are stained brown.The distribution pattern of two types of muscle fibers in gastrocnemius muscles is uniform and chessboard-like.The proportion of typeⅡmuscle fibers contained in the muscle is(72.2?6.8)%,much higher than that of typeⅠfibers which is(27.8?2.4)%(P