Isometric Tension Changes and Shortening in Muscle Strips During Post‐mortem Aging

Abstract

SUMMARY— Post‐mortem tension changes of rabbit psoas and beef geniohyoideus and semitendinosus muscle were studied. A special device was constructed and used to measure these changes while holding the muscle isometrically. It has been possible to demonstrate a pattern of tension development and cessation in rabbit muscle at 24°C and in beef muscle at 0°, 10°, and 24°C. With rabbit muscle no tension development was detected at 0° or 10°C. Initiation of tension development is affected by the ante‐mortem state of the animal as well as by temperature. The post‐mortem tension decline occurs after the disappearence of ATP and evidently is not related to ATP degradation. Possible relationships between post‐mortem tension changes and meat tenderness are discussed.

Subcellular events associated with the development and release of isometric tension in post-mortem bovine, rabbit and porcine skeletal muscle

“…It seems probable that the higher sensitivity of the E and M physiograph used in the present study made it possible to detect the small amount of tension developed between 3 and 6 hours post-mortem at 16°, whereas this small tension development was not detected by the earlier, less sensitive isometer (Jungk et al^., 1967).…”

“…Soon after the initial use of isometric tension in characterizing post-mortem isometric tension patterns, it was discovered that if post-mortem muscle strips remained attached to the instrument for 24-U8 hours, a gradual loss in ability of the strips to maintain their isometric tension development could be de tected (Jungk et al, 1967;Busch et a^., 1967). This loss in ability to maintain isometric tension was noticed first in bovine muscle at 2° where tension development was greater and where a low temperature delayed drying of the strip (Busch ^ al., 1967).…”

“…This was an important advantage over the earlier "isometer" in strument (Busch £_1-3 1967 ;Jungk et al, 1967) which measured isometric tension on only one strip at a time. Moreover, it became evident during the course of this investigation that the E and M physiograph and isometric transducers were more sensitive to small changes in isometric tension de velopment than the original "isometer"; this increased sensitivity re sulted in some changes in existing concepts concerning the effect of tem perature on post-mortem isometric tension patterns.…”

Light-scattering Raleigh linewidth measurements on G-actin

“…The ability to maintain isometric tension is lost (Jungk, Snyder, Goll & McConnell, 1967), but the muscle does not regain its extensibility. These changes during storage are believed to be caused by post-mortem autolysis.…”

“…Dubowitz, V. (1970) Muscle becomes hard and inextensible during the onset of rigor (Bendall, 1960), but during subsequent storage at 2°C there is a progressive increase in tenderness. The ability to maintain isometric tension is lost (Jungk, Snyder, Goll & McConnell, 1967), but the muscle does not regain its extensibility. These changes during storage are believed to be caused by post-mortem autolysis.…”