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- Title
Effect of repetitive stimulation on cell volume and its relationship to membrane potential in amphibian skeletal muscle.
- Authors
Usher-Smith, Juliet A.; Skepper, Jeremy N.; Fraser, James A.; Huang, Christopher L.-H.
- Abstract
The effect of electrical stimulation on cell volume, V c, and its relationship to membrane potential, E m, was investigated in Rana temporaria striated muscle. Confocal microscope xz-plane scanning and histology of plastic sections independently demonstrated significant and reversible increases in V c of 19.8±0.62% ( n=3) and 27.1±8.62% ( n=3), respectively, after a standard stimulation protocol. Microelectrode measurements demonstrated an accompanying membrane potential change, Δ E m, of +23.6±0.98 mV ( n=3). The extent to which this Δ E m might contribute to the observed changes in V c was explored in quiescent muscle exposed to variations in extracellular potassium concentration, [K+]e. E m and V c varied linearly with log [K+]e and [K+]e, respectively, in the range 2.5–15 mM ( R 2=0.99 and 0.96), and these results were used to reconstruct an approximately linear relationship between V c and E m (Δ V c=0.85 E m+68.53; R 2=0.99) and hence derive the Δ V c expected from the Δ E m during stimulation. This demonstrated that both the time course and magnitude of the increase and recovery of V c observed in active muscles could be reproduced by the corresponding [K+]e-induced depolarisation in quiescent muscles, suggesting that the depolarisation associated with membrane activity makes a substantial contribution to the cell swelling during exercise. Furthermore, conditions of Cl− deprivation abolished the relationship between E m and V c, supporting a mechanism in which the depolarisation of E m drives a passive redistribution of Cl− and hence cellular entry of Cl− and K+ and an accompanying, osmotically driven, increase in V c.
- Subjects
ELECTRIC stimulation; RANA temporaria; STRIATED muscle; HISTOLOGY; MUSCLES
- Publication
Pflügers Archiv: European Journal of Physiology, 2006, Vol 452, Issue 2, p231
- ISSN
0031-6768
- Publication type
Article
- DOI
10.1007/s00424-005-0022-9