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

Muscles of pigs with mutated calcium release channels show increased metabo lic activities, and ultimately inferior meat quality results. Different cel lular changes in the time period post mortem (PM) are reported by investiga ting 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 susce ptible (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 compare d to MHR muscle in the time period PM. The permeability of crude sarcoplasm ic reticulum (SR) to Ca2+ increased at a higher rate in MHS than in MHR mus cle. Total muscle phospholipids contained a higher concentration of long ch ain n-3 fatty acids in MHS compared with MHR animals immediately after slau ghter. The MHS homogenate lipids were more susceptible to stimulated peroxi dation by Fe2+/ascorbate in samples obtained 45 min PM and 4 h PM, but ther e were no differences between the two genotypes for 0 h PM and 22 h PM samp les, suggesting a retarded consumption of antioxidants in MHR compared to M HS muscle. The results suggest that in addition to the well-known denaturat ion of proteins, altered biochemical processes in muscle cells of stress-su sceptible pigs cause injury to cell membranes as well as to SR membranes ea rly in the time period PM.