Exercise increases the plasma membrane content of the Na+-K+ pump and its mRNA in rat skeletal muscles

被引:63
作者
Tsakiridis, T
Wong, PPC
Liu, Z
Rodgers, CD
Vranic, M
Klip, A
机构
[1] HOSP SICK CHILDREN,DIV CELL BIOL,TORONTO,ON M5G 1X8,CANADA
[2] UNIV TORONTO,DEPT PHYSIOL,TORONTO,ON M5S 1A8,CANADA
[3] UNIV TORONTO,DEPT MED,TORONTO,ON M5S 1A8,CANADA
[4] UNIV TORONTO,SCH PHYS & HLTH EDUC,TORONTO,ON M5S 1A1,CANADA
关键词
sodium-potassium-adenosinetriphosphatase; sodium-potassium pump; red muscles; white muscles; muscle fiber type; contraction; messenger ribonucleic acid;
D O I
10.1152/jappl.1996.80.2.699
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Muscle fibers adapt to ionic challenges of exercise by increasing the plasma membrane Na+-K+ pump activity. Chronic exercise training has been shown to increase the total amount of Na+-K+ pumps present in skeletal muscle. However, the mechanism of adaptation of the Na+-K+ pump to an acute bout of exercise has not been determined, and it is not known whether it involves alterations in the content of plasma membrane pump subunits. Here we examine the effect of 1 h of treadmill running (20 m/min, 10% grade) on the subcellular distribution and expression of Na+-K+ pump subunits in rat skeletal muscles. Red type I and IIa (red-I/IIa) and white type IIa and IIb (white-IIa/Hb) hindlimb muscles from resting and exercised female Sprague-Dawley rats were removed for subcellular fractionation. By homogenization and gradient centrifugation, crude membranes and purified plasma membranes were isolated and subjected to gel electrophoresis and immunoblotting by using pump subunit-specific antibodies. Furthermore, mRNA was isolated from specific red type I (red-I) and white type IIb (white-IIb) muscles and subjected to Northern blotting by using subunit-specific probes. In both red-I/IIa and white-IIa/IIb muscles, exercise significantly raised the plasma membrane content of the alpha(1)-subunit of the pump by 64 +/- 24 and 55 +/- 22%, respectively (P < 0.05), and elevated the alpha(2)-polypeptide by 43 +/- 22 and 94 +/- 39%, respectively (P < 0.05). No significant effect of exercise could be detected on the amount of these subunits in an internal membrane fraction or in total membranes. In addition, exercise significantly increased the alpha(1)-subunit mRNA in red-I muscle (by 50 +/- 7%; P < 0.05) and the beta(2)-subunit mRNA in white-IIb muscles (by 64 +/- 19%; P < 0.01), but the alpha(2)- and beta(1)-mRNA levels were unaffected in this time period. We conclude that increased presence of alpha(1)- and alpha(2)-polypeptides at the plasma membrane and subsequent elevation of the alpha(1)- and beta(2)-subunit mRNAs may be mechanisms by which acute exercise regulates the Na+-K+ pump of skeletal muscle.
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页码:699 / 705
页数:7
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