A comparison of shortening and Z line degradation in post‐mortem bovine, porcine, and rabbit muscle

Abstract

Ultrastructural changcs in bovine, porcine, and rabbit muscle have been studied during the first 24 hours post-mortem. Samples were taken for phase and electron microscopy immediately after death, after 4, 8, and 24 hours of post-mortem storage at 2' and 37"C, and after 24 hours post-mortem at 16" and 25°C. The results show that two kinds of structural changes occur in muscle during the first 24 hours post-mortem: ( a ) a variable amount of shortening, this shortening occurring via a sliding of filaments in all species and at all post-mortem storage temperatures examined, and ( b ) degradation of the 2 line, and at higher storage temperaturcs, of the M line also. Shortening of unrestrained muscle occurs soonest post-mortem at 37°C in all three species and is completed within four hours post-mortem in porcine and rabbit muscle and within eight hours post-mortem in bovine muscle. Post-mortem shorlening of unrestrained rabbit and porcine muscle is greatest at 37°C (sarcomere lengths of 1.5 b ) : shortening of rabbit muscle is minimal at 2'C (sarcomere length of 1.7 b j , but shortening of porcine muscle is minimal at 25°C (sarcomere length of 1.8 E L ) and is slightly greater at 2°C (sarcomere length of 1.6 p ) than at 16'C. Post-mortem shortening of bovine muscle is greatest at 2°C (sarcomere length of 1.3 p ) , is minimal at 16-25°C (sarcomerc lcngth of 1.8 p ) , and increases between 25-37°C (sarcomere lcngth of 1.5 p at 37°C). Sarconiere length measurements show that some variation occurs i n the extent 01 post-mortem shortening within the same muscle.Z line degradation occurs sooner post-mortem and to a greater extent at storage temperatures of 25°C or above than at temperatures of 16°C or below. Also, bovine muscle Z lines are clearly more resistant to post-mortem degradation than porcine or rabbit muscle 2 lines. Loss of fibrillar structure in porcine or rabhit muscle Z lines occurs during the first four hours post-mortem at 37'C, but cight hours of post-mortcni storage at 373C are required to caiise loss of fibrillar structure of bovine muscle 2 lines. After 24 hours at 25 or 37"C, Z lines of rabbit and porcine muscle are usually campletely absent; M lines are also frequently absent in this muscle.Changes that occur i n muscle during the onset of rigor mortis are of interest from several points of view. First, since postmortem muscle always experiences a loss of oxygen, ATP * and creatine phosphate as well as a variable decline in pH (BateSmith and Bendall, '49; Bendall, ' 6 0 ) , a study o f post-mortem muscle may provide insight into the effects of various nonphysiological conditions on the contractile apparatus. Secondly, it has been shown that muscle strips will shorten or develop isometric tension (Busch et al., '67) as they pass into rigor. This shortening or tension development resembles in. vizo contraction in several ways: (a) i t is initiated by an efflux of Ca++ from the sarcoplasrnic reticulum (Nauss and Davies, '66); (b) it uses ATP as an energy source (Bendall, '51, '60; Nauss and Da...

Techniques to reduce the temperature of beef muscle early in the post mortem period – a review

“…Henderson et al (1970) found that the values for temperature and pH at which shortening occurs depends on the species of animal and muscle type. For beef, shortening was maximal at 2 C, minimal in the range 16À25 C and high again at 37 C in beef (Henderson et al 1970).…”

“…Henderson et al (1970) found that the values for temperature and pH at which shortening occurs depends on the species of animal and muscle type. For beef, shortening was maximal at 2 C, minimal in the range 16À25 C and high again at 37 C in beef (Henderson et al 1970). Similarly Honikel et al (1986) found that sarcomeres in excised unrestrained bovine M. sternomandibularis incubated in a water bath shortened by 70% below 6 C, by less than 10% between 6 and 18 C and by 40% between 20 and 38 C. Hwang et al (2004) found however that sarcomere length was no different (P > 0.05) for excised M. longissimus (LL) incubated at 36 C (1.45 mm) than when incubated at 5 C (1.52 mm), with the least at 15 C (1.76 mm).…”

Effects of Prerigor Chilling and Freezing and Subcutaneous Fat Cover Upon the Histological and Shear Properties of Bovine Longissimus Dorsi Muscle

“…The contractile state of muscle has been reported to be influenced by the ambient temperature, the amount of tension on the muscle, and the postmortem glycolytic rate (Herring et al 1965;Herring 1968 , but that the greatest amount of shortening in excised muscle occurred at lower temperatures (Locker and Hagyard 1963;Henderson et al 1970). In addition, it has been observed that lamb longissimus dorsi muscle was tougher after being exposed to low temperatures during the first 16 h postmortem (Marsh et al 1968 (Jeremiah and Martin 1916, 1917, 1978.…”

The effect of calcium activated protease (CAF) and cathepsin D on bovine muscle myofibrils under varying conditions of pH and temperature

“…Stromer et al (1967) and Henderson et al (1970) observed a progressive slow loss of Z line and M line structures in postmortem muscles. The disappearance or weakening of M line structure was slower than changes in the Z line structure.…”

“…The loss of Z-line integrity has been proposed as one cause for the increase in tenderness that occurs in postmortem muscle (Stromer et al, 1967;Davey and Gilbert, 1969;Henderson et al, 1970;and Penny, 1970). The loss of Z line integrity may result in many breaks along the myofibril.…”