13C nuclear magnetic resonance spectroscopy – a non-invasive in vivo method to measure muscle glycogen metabolism in pigs of different genotypes
Abstract. The three ryanodine receptor 1 gene variants (NN: homozygous normal, Nn: heterozygous, nn: homozygous defective) and the degree of Hampshire origin (0 %, 25 %, 50 %) serve as model for the investigation of the in vivo glycogen muscle metabolism in 27 pigs. The pigs originate from 4 different cross-breeding lines with an age varying between 41 and 58 days and a body weight between 7.3 and 19 kg. 13C nuclear magnetic resonance spectroscopy was applied non-invasively in vivo and in a few pigs also post mortem to study the metabolic processes in the biceps femoris muscle after halothane exposure. In contrast to no visible effects of the halothane challenge test, the heterozygous defective allele carriers showed a drastic reduction in the level of glycogen (57 %) coupled with an increase in body temperature (1.36 °C). Overall, these changes were intermediate compared to the dramatic response in the homozygous nn genotype and to the very slow processes in NN, considering that the drastic glycogen depletion in the heterozygous genotype occurred after a rather long time of halothane exposure ( >20 min). In addition, pigs with the highest degree of Hampshire origin (50% → RN– allele frequency: ~31.5 %) showed the slowest glycogen depletion compared to pigs with a lower degree of Hampshire origin (0 or 25 %).