Cell injury and meat quality of pig in the time period post mortem from two genotypes susceptible or resistant to malignant hyperthermia

Abstract

Muscles of pigs with mutated calcium release channels show increased metabolic activities, and ultimately inferior meat quality results. Different cellular changes in the time period post mortem (PM) are reported by investigating longissimus samples obtained immediately after death (0 h), 45 min PM, 4 h PM, and 22 h PM. The meat quality of such malignant hyperthermia susceptible (MHS) pigs was inferior to that of malignant hyperthermia resistant (MHR) pigs. Histological analysis of muscle fibres showed an enhanced rate and extent of the development of extracellular spaces in MHS muscle compared to MHR muscle in the time period PM. The permeability of crude sarcoplasmic reticulum (SR) to Ca2+ increased at a higher rate in MHS than in MHR muscle. Total muscle phospholipids contained a higher concentration of long chain n-3 fatty acids in MHS compared with MHR animals immediately after slaughter. The MHS homogenate lipids were more susceptible to stimulated peroxidation by Fe2+/ascorbate in samples obtained 45 min PM and 4 h PM, but there were no differences between the two genotypes for 0 h PM and 22 h PM samples, suggesting a retarded consumption of antioxidants in MHR compared to MHS muscle. The results suggest that in addition to the well-known denaturation of proteins, altered biochemical processes in muscle cells of stress-susceptible pigs cause injury to cell membranes as well as to SR membranes early in the time period PM.