UNESP, Univ Estadual Paulista, Faculdade de Medicina Veterinária e Zootecnia, Departamento de Produção Animal, P. O. Box 560, 18618-000 Botucatu, São Paulo, Brazil.
Meat Sci. 2011 Jul;88(3):535-41. doi: 10.1016/j.meatsci.2011.02.007. Epub 2011 Feb 15.
This study aimed to evaluate myosin heavy chain (MyHC) isoform expression and muscle fiber types of Longissimus dorsi (LD) and Semitendinosus (ST) in Mediterranean buffaloes and possible fibers muscles modulation according to different slaughter weights. The presence of MyHC IIb isoforms was not found. Only three isoforms of MyHC (IIa, IIx/d and I) were observed and their percentages did not vary significantly among slaughter weights. The confirmation of the presence of hybrid muscles fibers (IIA/X) in LD and ST muscles necessitated classifying the fiber types into fast and slow according to their contractile activity, by m-ATPase assay. For both muscles, the muscle fiber frequency was higher for fast than for slow fibers in all weight groups. There was a difference (P<0.05) in the frequency of LD and ST muscle fiber types according to slaughter weights, which demonstrate that the slaughter weight influences the profile of muscle fibers from buffaloes.
本研究旨在评估长肌（LD）和半腱肌（ST）中肌球蛋白重链（MyHC）同工型的表达和肌肉纤维类型，以及根据不同的屠宰体重可能对肌肉纤维进行调节。未发现 MyHC IIb 同工型。仅观察到三种 MyHC（IIa、IIx/d 和 I）同工型，它们在屠宰体重之间的百分比没有显著差异。通过 m-ATPase 测定，证实 LD 和 ST 肌肉中存在混合肌肉纤维（IIA/X），需要根据其收缩活性将纤维类型分类为快肌和慢肌。对于这两种肌肉，在所有体重组中，快肌纤维的频率都高于慢肌纤维。LD 和 ST 肌肉纤维类型的频率根据屠宰体重存在差异（P<0.05），这表明屠宰体重影响了水牛肌肉纤维的分布。
