Enzyme activities of glycogen metabolism and mitochondrial characteristics in muscles of RN− carrier pigs (Sus scrofa domesticus)

Abstract

High glycogen content and abnormal mitochondria have been seen in muscles from RN carrier pigs in a previous work. Glycogen synthase, branching enzyme, phosphorylase and debranching enzyme activities, and mitochondrial characteristics were studied in normal and RN⁻ carrier pigs. Branching enzyme activity was higher ($\text{P < 0.01}$) and glycogen synthase activity tended to be higher in longissimus dorsi muscle from RN⁻ carrier pigs compared to normal pigs. There were no differences in the activities of either phosphorylase and debranching enzyme between both types of pigs. Citrate synthase activity and mitochondrial respiration were slightly higher in muscle from RN⁻ pigs compared to normal pigs. Glycogen content in muscle from RN⁻ pigs could result from the imbalance between anabolic and catabolic enzyme activities of glycogen metabolism. The higher specific activity in mitochondria of RN⁻ pigs muscle might be the compensatory effect of an abnormal glycolytic metabolism.