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. 1972 Mar 1;59(3):347–359. doi: 10.1085/jgp.59.3.347

The Capacitance of Skeletal Muscle Fibers in Solutions of Low Ionic Strength

P C Vaughan 1, J N Howell 1, R S Eisenberg 1
PMCID: PMC2203175  PMID: 4536730

Abstract

The capacitance of skeletal muscle fibers was measured by recording with one microelectrode the voltage produced by a rectangular pulse of current applied with another microelectrode. The ionic strength of the bathing solution was varied by isosmotic replacement of NaCl with sucrose, the [K] [Cl] product being held constant. The capacitance decreased with decreasing ionic strength, reaching a value of some 2 µF/cm2 in solutions of 30 mM ionic strength, and not decreasing further in solutions of 15 mM ionic strength. The capacitance of glycerol-treated fibers did not change with ionic strength and was also some 2 µF/cm2. It seems likely that lowering the ionic strength reduces the capacitance of the tubular system (defined as the charge stored in the tubular system), and that the 2 µF/cm2 which is insensitive to ionic strength is associated with the surface membrane. The tubular system is open to the external solution in low ionic strength solutions since peroxidase is able to diffuse into the lumen of the tubules. Twitches and action potentials were also recorded from fibers in low ionic strength solutions, even though the capacitance of the tubular system was very small in these solutions. This finding can be explained if there is an action potential—like mechanism in the tubular membrane.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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