IN-VIVO AND POSTMORTEM STUDY OF MUSCLE METABOLISM IN PIGS OF DIFFERENT MHS GENOTYPE BY MEANS OF P-31-NMR SPECTROSCOPY

P-31 magnetic resonance spectroscopy was applied to study in vivo chan ges of muscle phosphorous metabolites (inorganic phosphate - P-i, Crea tinphosphate - PCr and Adenosintriphosphate - ATP) and pH values durin g halothane exposure in pigs of different MHS genotype weighing from 1 9 to 55 kg. MHS genotypes were differentiated by ryanodine receptor ge ne test. Homozygous stress susceptible (Pietrain, n=7), heterozygous ( German Landrace, n=16) and homozygous stress resistant (German Landrac e, n=1Z) pigs were included in this study. The Nn genotypes showed dra matic changes in their muscle metabolism after administration of halot hane (2 Vol.%). Differences between Nn and NN pigs were significant (P <0.05) in initial PCr/P-i and PCr/ATP values, but disappeared after ad ministration of halothane. After slaughter (average slaughter weight 6 6.3 kg for NN and 58.4 kg for Nn genotypes) significant differences (P <0.05) in kinetic parameters for time course changes of PCr and Pi and rate of pH fall occurred. NN pigs had a 6.2 min longer half time brea kdown of PCr. Nn genotypes showed a more distinct decline of pH (8.5 . 10(-3) units per min) than NN pigs (3.6.10(-3) units per min).