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F32C FREE COMMUNICATION/SLIDE CELLULAR AND REGULATORY MECHANISMS IN HEART AND SKELETAL MUSCLE

PROLONGED EXERCISE AND NA+-K+-ATPASE ACTIVITY IN RAT SKELETAL MUSCLE

Fowles, J1; Barr, D1; Duhamel, T1; Sandiford, S1; Schertzer, J1; Green, H1

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Medicine & Science in Sports & Exercise: May 2001 - Volume 33 - Issue 5 - p S268
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The purpose of this study was to investigate the hypothesis that an acute bout of prolonged running exercise would result in a depression of maximal Na+-K+-ATPase activity in rat locomotor muscles, an effect that would be reversed during active recovery. Female Sprague Dawley rats (291 ± 9.8 gm, ± SE, n = 15), either ran on a treadmill (RUN) at 21m/min and 8% grade until fatigue or to a maximum of 2 h, acted as control (CON) or exercised for an additional 45 min at 10 m/min and % grade (REC). Tissue obtained from the soleus (SOL), red (RV) and white (WV) vastus lateralis was extracted and measured for Na+-K+-ATPase activity using the artificial substrate, 3-0-methylfluorescein (3-0MF). Although differences in 3-0MF were observed between tissue types (SOL > RV > WV; P < 0.05), the 1.7, 15.0 and 9.1% reductions observed for SOL, RV and WV, respectively in RUN were not significant (P > 0.05). Similarly not differences (P > 0.05) were observed between CON and REC regardless of tissue type. Values ± SE (μmol/h/mg protein) It is concluded that although the low intensity aerobic exercise induced a trend towards reductions in Na+-K+-ATPase activity, indicating possible structural alterations in the enzyme, the effects were not significant regardless of the fiber type characteristics of the locomotor muscles examined.

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©2001The American College of Sports Medicine