Na⁺-K⁺-ATPase α2-gene and skeletal muscle characteristics in response to long-term overfeeding

The role of Na + -K + -ATPase α2-gene BglII polymorphism in the changes of skeletal muscle metabolic properties after a 100-day overfeeding protocol conducted with 12 pairs of monozygotic twins is reported. The activities of oxoglutarate dehydrogenase (OGDH) and phosphofructokinase (PFK) were determined from muscle biopsies. A larger increase in the total fat mass (127 vs. 61%) ( P < 0.05) and low-density lipoprotein cholesterol (20 vs. 0.7%) ( P = 0.05) in 8.0/8.0-kb [3.3-kb negative (−); n = 7 pairs] than in 8.0/3.3 + 3.3/3.3-kb [3.3-kb positive (+); n = 5 pairs] subjects was observed. OGDH activity decreased in 3.3-kb − (−15%), whereas PFK (+26%) as well as the PFK-to-OGDH ratio (90%) increased. In contrast, among 3.3-kb + , OGDH increased (+54%) together with a decrease in PFK (−1%) and PFK-to-OGDH ratio (−5%). These changes were significantly different between genotypes ( Pfrom <0.05 to 0.01). In conclusion, fat mass, low-density lipoprotein cholesterol, and skeletal muscle glycolytic-to-oxidative enzyme ratio increased more in the α2-gene 3.3-kb − subjects with overfeeding, suggesting more unfavorable metabolic changes compared with the 3.3-kb + subjects.