Histochemical fiber composition of cat's tail muscles.

Abstract

A histochemical analysis was performed on the activity of myofibrillar ATPase following preincubation at pH 10.3 with NADH-diaphorase in the cat tail muscles (ECM; extensor caudae medialis, ECL; extensor caudae lateralis, ACE; abductor caudae externus, ACI; abductor caudae internus, FCL; flexor caudae longus, and FCB; flexor caudae brevis). Muscles contained three types of muscle fibers: FG (fast-twitch glycolytic) showed high reaction of myofibrillar ATPase staining and low reaction in NADH-diaphorase staining; FOG (fast-twitch oxidative glycolytic) showed high reaction in myofibrillar ATPase staining and high reaction in NADH-diaphorase staining; and SO (slow-twitch oxidative) showed low reaction in myofibrillar ATPase staining and high reaction in NADH-diaphorase staining. All 6 tail muscles were composed of these three types of fibers, but proportions differed in each tail muscle. Proportions of SO and FG fibers were highest in ECL (SO: 38.6 ± 2.3, S.D. %) and ACI (FG: 59.2 ± 5.0%), respectively. The diameters of the fibers were also measured (SO; 50.47 ± 3.12, FOG; 58.18 ± 2.78, FG; 70.91 ± 3.40, S.D. microns).