Influence of interposition of pink muscle fiber into dorsal ordinary muscle on increasing rate of K-value in various fish species

Abstract

Twenty‐seven fish species from the Sakishima Islands and Nagasaki living in water temperatures of 28°C (12 fish species) and 17°C (15 fish species), respectively, were used as sample fishes. Postmortem temporal changes of K‐values were measured at 1‐h intervals in the dorsal ordinary muscle of each fish, of which the remaining body was then kept in water at a controlled temperature of 32°C. The increasing rate of K‐value at 32°C (ΔK32) was calculated from the regression line formed from the relationship between the kept time and the K‐value. Muscle fiber types were differentiated by the stability of actomyosin ATPase preincubated in either acid or alkaline conditions. ΔK32 varied widely according to fish species, ranging from 0.98%/h to 14.00%/h. Although the mean value of each body of water was somewhat higher for fishes from Nagasaki at 17°C than in fishes from Sakishima Islands at 28°C, the difference was not significant. The interposition percentage of pink muscle fibers into the dorsal ordinary muscle was also distributed widely, ranging from 0% to 56.53% in number and from 0% to 53.68% in area. A significant correlation was recognized in the relationship between the number or area percentage of pink muscle fibers and deviation percentage of ΔK32 for all fish species sampled; r = 0.411 (P < 0.05) for number percentage and r = 0.518 (P < 0.01) for area percentage. These results suggest that the interposition of pink muscle fibers into the dorsal ordinary muscle might accelerate a temporal change of K‐value in fish.

Comparison of 5'-inosine monophosphate and p-nitrophenyl phosphate degrading activities among red, pink, and white muscle fibers of cultured carp

“…[14][15][16] As previously reported, the ordinary muscle part near the intermediate muscle layer in carp was composed of pink and of subtypes like IIa and IIb of white muscle fibers. 14,15 The pink muscle fibers, however, gradually decreased in number inwards, and became unrecognizable in the innermost part of ordinary muscle. 14,17 We have reported that the temporal change in Kvalue of carp was fastest in red, followed by pink, and white muscle fibers.…”

“…Therefore, most histochemical studies have focused on these distinct layers, 8–13 and only a few have dealt with the different muscle fiber types in the ordinary muscle of fish. In a series of studies that we have recently conducted, we reported that the dorsal ordinary muscle in many fish species is composed of not only white but also pink muscle fibers arranged in a mosaic pattern 14–16 . As previously reported, the ordinary muscle part near the intermediate muscle layer in carp was composed of pink and of subtypes like IIa and IIb of white muscle fibers 14,15 .…”

“…In a series of studies that we have recently conducted, we reported that the dorsal ordinary muscle in many fish species is composed of not only white but also pink muscle fibers arranged in a mosaic pattern 14–16 . As previously reported, the ordinary muscle part near the intermediate muscle layer in carp was composed of pink and of subtypes like IIa and IIb of white muscle fibers 14,15 . The pink muscle fibers, however, gradually decreased in number inwards, and became unrecognizable in the innermost part of ordinary muscle 14,17 …”

“…A similar tendency was recognized at 32°C (Table 1). We recently reported that the dorsal ordinary muscle in many fish species is composed of not only white but also pink muscle fibers arranged in a mosaic pattern 14–16 . Furthermore, the percentage of pink muscle fibers interposed in the dorsal ordinary muscle varies widely among fish species 15 .…”

Relationship between the characteristics of rigor‐mortis‐related actomyosin and muscle fiber types in the ordinary muscle of various fishes

“…The ordinary muscle of cultured carp near the intermediate muscle layer was composed of three muscle fiber types: the pink muscle fiber and white muscle fiber IIa and IIb subtypes, whereas the innermost ordinary muscle consisted only of white muscle fiber IIa and IIb subtypes . By contrast, the percentages of interposition of pink muscle fibers in the dorsal ordinary muscle were distributed widely, ranging from 0% to 56.5% in number and from 0% to 53.7% in area . It is well known that rigor mortis of the muscle after death occurs when the ATP concentration decreases to a level no longer sufficient to support the removal of the connection between myosin and actin filaments of the myofibrils .…”