Subcellular distribution and immunocytochemical localization of Na,K-ATPase subunit isoforms in human skeletal muscle

The present study tested the hypothesis that exercise with a large compared with a small active muscle mass results in a higher contraction-induced increase in Na+-K+-ATPase mRNA expression due to greater hormonal responses. Furthermore, the relative abundance of Na+-K+-ATPase subunit α1, α2, α3, α4, β1, β2, and β3 mRNA in human skeletal muscle was investigated. On two occasions, eight subjects performed one-legged knee extension exercise (L) or combined one-legged knee extension and bilateral arm cranking (AL) for 5.00, 4.25, 3.50, 2.75, and 2.00 min separated by 3 min of rest. Leg exercise power output was the same in AL and L, but heart rate at the end of each exercise interval was higher in AL compared with L. One minute after exercise, arm venous blood lactate was higher in AL than in L. A higher level of blood epinephrine and norepinephrine was evident 3 min after exercise in AL compared with L. Nevertheless, none of the exercise-induced increases in α1, α2, β1, and β3 mRNA expression levels were higher in AL compared with L. The most abundant Na+-K+-ATPase subunit at the mRNA level was β1, which was expressed 3.4 times than α2. Expression of α1, β2, and β3 was less than 5% of the α2 expression, and no reliable detection of α3 and α4 was possible. In conclusion, activation of additional muscle mass does not result in a higher exercise-induced increase in Na+-K+-ATPase subunit-specific mRNA.

Download Full-text

Alterations in levels of Na(+)-K(+)-ATPase isoforms in heart, skeletal muscle, and kidney of diabetic rats

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1993.265.2.e243 ◽

1993 ◽

Vol 265 (2) ◽

pp. E243-E251 ◽

Cited By ~ 6

Author(s):

Y. C. Ng ◽

P. H. Tolerico ◽

C. B. Book

Keyword(s):

Skeletal Muscle ◽

Atpase Activity ◽

Cardiac Muscle ◽

Insulin Treatment ◽

Marked Decrease ◽

Diabetic Rats ◽

Cellular Mechanisms ◽

Atpase Subunit ◽

Subunit Isoforms ◽

Specific Regulation

In streptozotocin (STZ)-induced diabetic rats, activities of Na(+)-K(+)-ATPase and the Na pump have been shown to be altered. Cellular mechanisms underlying such changes remain unclear. The present studies examined by immunoblotting the levels of Na(+)-K(+)-ATPase subunit isoforms in heart, skeletal muscle, and kidney of diabetic rats. Effects of insulin treatment on these levels were also studied. In cardiac muscle, STZ-induced diabetes caused a marked decrease in alpha 2-levels, a moderate decrease in beta 1-levels, and no significant change in alpha 1-levels. Corresponding to these changes, Na(+)-K(+)-ATPase activity, estimated by K(+)-dependent p-nitrophenylphosphatase activity, also decreased. By contrast, there were significant increases in alpha 1- and alpha 2-levels in skeletal muscle and in alpha 1- and beta 1-levels in kidneys of diabetic rats. There was also a detectable, but not significant, increase in beta 1-levels in diabetic skeletal muscle. In kidney, the increase in subunit levels was associated with significantly increased Na(+)-K(+)-ATPase activity, whereas, in skeletal muscle, no increase in enzyme activity was observed. In diabetic rats, 7 days of insulin treatment (10 U/kg sc) partially reversed the decreased alpha 2- and beta 1-levels in diabetic cardiac muscle, without significant effect on alpha 1-levels. In skeletal muscle, insulin treatment also partially reversed the elevated alpha 1- and alpha 2-levels but was without significant effect on beta 1-levels. It is concluded that STZ-induced diabetes exerted isoform- and tissue-specific regulation of the Na(+)-K(+)-ATPase subunit isoforms.(ABSTRACT TRUNCATED AT 250 WORDS)

Download Full-text

Fiber type-specific immunostaining of the Na+,K+-ATPase subunit isoforms in skeletal muscle: Age-associated differential changes

Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease ◽

10.1016/j.bbadis.2006.08.006 ◽

2006 ◽

Vol 1762 (9) ◽

pp. 783-793 ◽

Cited By ~ 18

Author(s):

Lianqin Zhang ◽

Keith J. Morris ◽

Yuk-Chow Ng

Keyword(s):

Skeletal Muscle ◽

Fiber Type ◽

Atpase Subunit ◽

Subunit Isoforms

Download Full-text

Effect of exercise and training on phospholemman phosphorylation in human skeletal muscle

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00533.2010 ◽

2011 ◽

Vol 301 (3) ◽

pp. E456-E466 ◽

Cited By ~ 24

Author(s):

Boubacar Benziane ◽

Ulrika Widegren ◽

Sergej Pirkmajer ◽

Jan Henriksson ◽

Nigel K. Stepto ◽

...

Keyword(s):

Skeletal Muscle ◽

Human Skeletal Muscle ◽

Acute Exercise ◽

Vastus Lateralis ◽

Exercise Bout ◽

Short Term ◽

Atpase Subunit ◽

Acute Bout ◽

Subunit Expression ◽

The Impact

Phospholemman (PLM, FXYD1) is a partner protein and regulator of the Na+-K+-ATPase (Na+-K+ pump). We explored the impact of acute and short-term training exercise on PLM physiology in human skeletal muscle. A group of moderately trained males ( n = 8) performed a 1-h acute bout of exercise by utilizing a one-legged cycling protocol. Muscle biopsies were taken from vastus lateralis at 0 and 63 min (non-exercised leg) and 30 and 60 min (exercised leg). In a group of sedentary males ( n = 9), we determined the effect of a 10-day intense aerobic cycle training on Na+-K+-ATPase subunit expression, PLM phosphorylation, and total PLM expression as well as PLM phosphorylation in response to acute exercise (1 h at ∼72% V̇o2peak). Biopsies were taken at rest, immediately following, and 3 h after an acute exercise bout before and at the conclusion of the 10-day training study. PLM phosphorylation was increased both at Ser63 and Ser68 immediately after acute exercise (75%, P < 0.05, and 30%, P < 0.05, respectively). Short-term training had no adaptive effect on PLM phosphorylation at Ser63 and Ser68, nor was the total amount of PLM altered posttraining. The protein expressions of α1-, α2-,and β1-subunits of Na+-K+-ATPase were increased after training (113%, P < 0.05, 49%, P < 0.05, and 27%, P < 0.05, respectively). Whereas an acute bout of exercise increased the phosphorylation of PKCα/βII on Thr638/641 pre- and posttraining, phosphorylation of PKCζ/λ on Thr403/410 was increased in response to acute exercise only after the 10-day training. In conclusion, we show that only acute exercise, and not short-term training, increases phosphorylation of PLM on Ser63 and Ser68, and data from one-legged cycling indicate that this effect of exercise on PLM phosphorylation is not due to systemic factors. Our results provide evidence that phosphorylation of PLM may play a role in the acute regulation of the Na+-K+-ATPase response to exercise.

Download Full-text