E-14E Free Communication/Slide Skeletal Muscle Metabolism
The Na+-K+-ATPase in skeletal muscle is a highly adaptable enzyme, and has been shown to increase following exercise training. At present, it is unclear how the upregulation Na+-K+-ATPase content can be explained through alterations in the specific subunits and their isoforms: 〈1, 〈2, ®1, and ®2.
To examine the effect of prolonged aerobic training on Na+-K+-ATPase protein content and subunit isoform distribution.
Ten healthy untrained males (21.4 ± 0.3yrs) performed submaximal single leg cycling for 10 weeks. Training began at 75% pretraining power output, for 30 min, 3 times per week, and progressed to 60 min 5 times per week. Needle biopsies were taken from the vastus lateralis muscle of the trained leg before the training period (PRE), and from both control (CON) and trained (TR) legs following the training. Na+-K+-ATPase protein content was measured using the 3H-ouabain binding technique, and relative subunit isoform content with Western blotting.
Protein content of the Na+-K+-ATPase (281±11) increased (p < 0.05) in TR (326±16) as a result of training. The training also resulted in elevated (p < 0.05) protein levels for 〈1 (116±1.2%), 〈2 (112±4.6%), and 〈1 (112±2.7%) subunits in TR compared to PRE. No changes were seen in the ®2 subunit with training. No changes were observed between CON vs. PRE leg for either 3H-ouabain binding or Western blotting.
These results indicate that increases in 〈1, 〈2, ®1 subunit isoforms are responsible for the training induced increase Na+-K+-ATPase content. Supported by NSERC Canada