CONTRACTILE AND HISTOCHEMICAL PROPERTIES OF THE INFERIOR OBLIQUE MUSCLE IN THE RAT AND IN THE CAT

Publisher Website
Google Scholar
Abstract
Mechanical and histochemical properties of inferior oblique muscles (IO) were compared in adult albino rat and pigmented cat. The twitch contraction times and the fusion frequencies were about the same in both species indicating similar contractile properties of the fast contracting fibers. Rat IO seemed to contain fewer slowly contracting fibers than cat IO; half-decay time of the twitch was shorter in rat than in cat muscles and fusion started at higher stimulus frequencies. Fatigue resistance was lower in rat than in cat. Post-tetanic potentiation occurred in the cat, but not in the rat, IO. Almost all fibers of rat IO were rich in myofibrillar ATPase. In cat IO most fibers showed high myofibrillar ATPase activity, but some fibers in the global layer had moderate to small amounts of this enzyme. This correlates well with the physiological differences between cat and rat IO.