Role of Na(+)-K+ pump and Na+ channel concentrations in the contractility of rat soleus muscle

The American Journal of Physiology
A P HarrisonT Clausen

Abstract

The dependence of contractile performance on the leak-to-pump ratio for Na+ has been examined. In isolated rat soleus muscle the concentration of Na(+)-K+ pumps was shown to decrease with age (-57%) or K+ deficiency (-69%), whereas Na+ channel concentration remained constant. This relative increase in the ratio between Na+ channels and Na(+)-K+ pumps was associated with a markedly faster rate of force decline (58 and 97%, respectively; both P < 0.001) during stimulation at 90 Hz and reduced subsequent force recovery (-34 and -38%, respectively; both P < 0.001). Similar effects were elicited by acute inhibition of Na(+)-K+ pump activity with ouabain. Preincubation with aconitine and veratridine, resulting in a 91 and 118% increase in Na+ influx per contraction, respectively (both P < 0.05), significantly hastened the initial rate of force decline (19%; P < 0.05 for aconitine and 69%; P < 0.001 for veratridine) and slowed recovery (-59 and -86%, respectively, both P < 0.001). It is concluded that the ratio between excitation-induced Na+ influx and Na(+)-K+ pump capacity is an important determinant for endurance and rate of recovery of force in skeletal muscle.

Citations

Nov 9, 2006·American Journal of Physiology. Endocrinology and Metabolism·W A MacdonaldO B Nielsen
Sep 24, 2005·Journal of Applied Physiology·Alison R HarmerJeff R Flack
Jan 20, 2007·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·K T Murphy, T Clausen
Mar 17, 2007·The Journal of Physiology·Marika L ArmstrongCoral L Murrant
Oct 17, 2002·Journal of Applied Physiology·J R FowlesA R Tupling
Aug 24, 2000·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·H Gissel, T Clausen
Oct 4, 2000·Physiological Reviews·O M Sejersted, G Sjøgaard
Jun 9, 2000·Annual Review of Physiology·A J Hulbert, P L Else
Sep 25, 2003·Physiological Reviews·Torben Clausen
Mar 26, 2005·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·A C PetersenM J McKenna

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