Influence of interposition of pink muscle fiber into dorsal ordinary muscle on increasing rate of K-value in carp [Cyprinus carpio] (cultured)

In order to clarify the influence of the interposition of pink muscle fiber into the dorsal ordinary muscle on the post-mortem temporal change of K-value, using carp (cultured) Cyprinus carpio, the dorsal muscle was divided into five muscle parts toward depth with the naked eye, as follows: the dark muscle part (P-l), the intermediate muscle part (P-2), and three ordinary muscle parts (P-3, P-4, P-5). The muscle fiber types in these parts were discriminated by the inactivation of actomyosin ATPase activity for both acid and alkaline preincubations, and the temporal changes of ATP related compounds in these parts were then measured at a kept temperature of 32degC. Five muscle parts were organized from the muscle fiber types as follows: P-1 was organized from only red muscle fiber type, P-2 from only pink muscle fiber type in a thin layer and from two muscle fiber types of not only pink muscle fiber, but also white muscle fiber of the 2 a or 2 b subtype in a region of mosaic pattern, and all of P-3, P-4, and P-5 were from two muscle fiber types of white muscle fiber (2 a or 2 b subtype) and pink muscle fiber, respectively. The temporal changes of K-value were remarkably faster in order of the dark muscle part of P-1, the intermediate muscle part of P-2, three ordinary muscle parts of P-3, P4, and P-5, although its change did not exhibit a remarkable difference among three ordinary muscle parts. On the other hand, the temporal change of K-value among muscle fiber types was considerably different and remarkably faster in the order of: red muscle fiber, pink muscle fiber, and white muscle fiber. From these results, it was considered that the interposition of pink muscle fiber into the dorsal ordinary muscle might accelerate the temporal change of K-value.