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Comparative studies of the mitochondrial properties of longissimus dorsi muscles of pietrain and large white pigs
Author(s) -
Cheah K. S.
Publication year - 1973
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740240109
Subject(s) - mitochondrion , cytochrome c oxidase , biology , cytochrome c , longissimus dorsi , respiration , biochemistry , chemistry , anatomy , zoology
Investigations, using various techniques (electron microscopy, polarography, spectrophotometry), on mitochondria isolated immediately post ‐ mortem from the Longissimus dorsi (LD) muscles of stress‐susceptible (SS) Pietrain and stressresistant (SR) Large White pigs suggest no marked biochemical difference in their mitochondrial properties. There was no evidence of “uncoupling” 2 nor of aberrant mitochondrial energy metabolism” 3 in the mitochondria of either breed of pig. The difference observed between the two breeds in mitochondrial cytochrome c content, in the State 3 rate of oxidation of succinate and of ascorbate plus tetramethyl‐ p ‐phenylenediamine (TMPD) and in the maximum time of mitochondrial storage in situ , could be attributed mainly to differences in initial muscle pH values and in the subsequent rates of pH decline post ‐ mortem . With both breeds of pig intact mitochondria could still be isolated from LD muscle even after prolonged storage as long as the ultimate tissue pH was not below 5.5. Prolonged storage of mitochondria in situ caused a loss of mitochondrial cytochrome c , which was responsible for a decline in the State 3 respiration. The latter could be restored by addition of cytochrome c and ADP. The cytochrome oxidase activity (e.c. 1.9.3.1) was the most stable to post ‐ mortem ageing both in situ (1 °C) and in vitro (0 °C), and the NAD + ‐linked oxidation of pyruvate plus malate, the least stable. The small observed differences in immediate post ‐ mortem mitochondrial function between SR and markedly SS pigs cannot possibly account for the very large differences in post ‐ mortem biochemical behaviour and particularly not for the low initial pH and high rate of post ‐ mortem pH fall, characteristic of SS pigs showing the pale, soft and exudative (PSE) condition.