Abstract
We assessed the effects of age and endurance exercise training (treadmill running at 75% maximal running capacity, 1 h/day, 5 days/wk for 10 wk) on the total concentration of insulin-regulatable glucose transporters (GLUT-4) and GLUT-4 mRNA levels in the myocardium of male Fischer 344 rats aged 7, 15, and 25 mo. Myocardial GLUT-4 concentration was quantified with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting and detected with a polyclonal antibody to the GLUT-4 transporter. Myocardial GLUT-4 mRNA levels were quantified with slot-blot analysis and a cDNA probe for GLUT-4. Myocardial GLUT-4 concentration in the 25-mo group decreased 27 and 20% compared with the 7- and 15-mo groups, respectively (P < 0.0001 and P < 0.003). GLUT-4 mRNA also decreased significantly in the 25-mo group compared with the 7-mo group (20% in the trained and 11% in the untrained group, P < 0.05). Endurance training did not significantly affect myocardial GLUT-4 concentrations in any age group despite a significant increase in GLUT-4 mRNA in the 7- and 25-mo trained groups. In conclusion, myocardial GLUT-4 protein levels in the rat are significantly decreased with age but are unaffected by 10 wk of treadmill running.
Original language | English (US) |
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Pages (from-to) | 328-332 |
Number of pages | 5 |
Journal | Journal of applied physiology |
Volume | 76 |
Issue number | 1 |
DOIs | |
State | Published - 1994 |
Keywords
- aging
- glucose transport
- glycolysis
- heart