Effect of exercise on proglycogen and macroglycogen content in skeletal muscles of pigs with the Rendement Napole mutation.
OBJECTIVE
To investigate influence of the Rendement Napole (RN-) mutation on proglycogen (PG) and macroglycogen (MG) content in skeletal muscles before and after exercise and evaluate glycogen concentrations within various muscle fiber types.


METHODS
5 pigs with the RN- mutation and 3 noncarrier pigs.


METHODS
Pigs performed 2 exercise tests on a treadmill. In the first, pigs (mean body weight, 27 kg) ran a distance of approximately 800 m. In the second, pigs (mean body weight, 63 kg) ran until fatigued. Biopsy specimens (biceps femoris muscle) for determination of PG and MG contents were obtained before and after exercise, 24 hours after the first test, and 3 hours after the second test. Histochemical analysis was performed on specimens obtained before and after the second test.


RESULTS
Before exercise, PG stores did not differ markedly between groups, but MG stores were twice as high in pigs with the RN- mutation, compared with noncarrier pigs. The MG content decreased to a similar extent in both groups after exercise. Resynthesis of MG was greater in pigs with the RN- mutation than in noncarrier pigs by 3 hours after exercise. A low glycogen content after exercise was observed in many type I and type IIA fibers and in some type lIB fibers.


CONCLUSIONS
The RN- mutation was associated with high MG stores in skeletal muscle that did not influence exercise performance. The RN- mutation did not impair glycogenolysis during exercise but may induce faster resynthesis of MG after exercise.
Essén-Gustavsson
Birgitta
B
Department of Clinical Sciences, Section for Comparative Physiology and Medicine, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, S-750 07, Uppsala, Sweden.
Jensen-Waern
Marianne
M
Jonasson
Robert
R
Andersson
Leif
L
D055372:AMP-Activated Protein Kinases; D000818:Animals; D005260:Female; D006003:Glycogen / Q000378:metabolism*; D006614:Hindlimb; D009097:Multienzyme Complexes / Q000235:genetics*; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D020125:Mutation, Missense; D005082:Physical Exertion; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D013552:Swine / Q000235:genetics* / Q000378:metabolism*
D009097:Multienzyme Complexes; D006003:Glycogen; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases