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Title: MUSCLE METABOLISM AND BODY COMPOSITION OF PIGS WITH DIFFERENT RYANODINE RECEPTOR GENOTYPES STUDIED BY MEANS OF 31P NUCLEAR MAGNETIC SPECTROSCOPY AND 1H MAGNETIC RESONANCE IMAGING

Author
item SCHOLZ, ARMIN - HUMBOLDT UNIVERSITY
item Mitchell, Alva
item WANG, P - HOWARD UNIVERSITY
item SONG, H - HOWARD UNIVERSITY
item YAN, Z - HOWARD UNIVERSITY

Submitted to: Archives of Animal Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Pigs that inherit the genes that produces a condition called porcine stress syndrome are known to develop larger muscles and less fat, but also have problems related to energy metabolism in their muscles. The purpose of this study was to use nuclear magnetic resonance techniques (NMR spectroscopy or imaging) to evaluate differences in both energy metabolism in the muscle and body composition of live pigs that were either stress susceptible or non stress susceptible. After only a few minutes exposure to stress by way of an anesthetic, NMR spectroscopy revealed that the susceptible pigs exhibited dramatic changes in muscle energy status, whereas, normal pigs remained unchanged for as long as an hour. Pigs which had inherited only one of the two genes necessary for stress susceptible condition were more like the normal pigs. NMR imaging showed that by the time the pigs weighed only about 20 pounds the stress susceptible pigs already were developing larger muscles than the other two groups. These results contribute to a better understanding of the metabolic processes that result when pigs inherit one or both of the genes responsible for the porcine stress syndrome.

Technical Abstract: 31P nuclear magnetic resonance spectroscopy was performed on 4 to 9 week old pigs to study malignant hyperthermia as part of the porcine stress syndrome by observing in vivo and post mortem changes of muscle phosphorous metabolites, pH values and body temperature during halothane exposure. Homozygous stress nonsensitive pigs (NN; 21 pigs in vivo and 3 pigs post mortem) were compared with heterozygous (Nn; 25/4) and homozygous stress susceptible pigs (nn; 13/3). The genotypes were identified by the ryanodine receptor gene test using a polymerase chain reaction technique. The nn genotypes showed a more dramatic change in their muscle metabolism than did the Nn and NN pigs. The muscle metabolism of the NN genotypes changed very slowly, while the Nn genotypes showed the highest variation. Overall, Nn had an intermediate response to halothane with a tendency to NN during the in vivo study. In the same context, the volume of both M. longissimus dorsi (MLD) and the overlying fat was measured on 61 of the above 69 pigs. A saddle shaped surface coil was used to generate five continuous axial images between 14th and 12th vertebra. The homozygous stress susceptible pigs had a significantly larger MLD volume at 10 kg body weight than the heterozygous and homozygous stress non sensitive pigs.