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. 1992 Jun 1;99(6):985–1016. doi: 10.1085/jgp.99.6.985

Separation of Q beta and Q gamma charge components in frog cut twitch fibers with tetracaine. Critical comparison with other methods

PMCID: PMC2216622  PMID: 1640223

Abstract

Charge movement was measured in frog cut twitch fibers with the double Vaseline-gap technique. 25 microM tetracaine had very little effect on the maximum amounts of Q beta and Q gamma but slowed the kinetics of the I gamma humps in the ON segments of TEST-minus-CONTROL current traces, giving rise to biphasic transients in the difference traces. This concentration of tetracaine also shifted V gamma 3.7 (SEM 0.7) mV in the depolarizing direction, resulting in a difference Q-V plot that was bell-shaped with a peak at approximately -50 mV. 0.5-1.0 mM tetracaine suppressed the total amount of charge. The suppressed component had a sigmoidal voltage distribution with V = -56.6 (SEM 1.1) mV, k = 2.5 (SEM 0.5) mV, and qmax/cm = 9.2 (SEM 1.5) nC/microF, suggesting that the tetracaine-sensitive charge had a steep voltage dependence, a characteristic of the Q gamma component. An intermediate concentration (0.1-0.5 mM) of tetracaine shifted V gamma and partially suppressed the tetracaine-sensitive charge, resulting in a difference Q- V plot that rose to a peak and then decayed to a plateau level. Following a TEST pulse to greater than -60 mV, the slow inward current component during a post-pulse to approximately -60 mV was also tetracaine sensitive. The voltage distribution of the charge separated by tetracaine (method 1) was compared with those separated by three other existing methods: (a) the charge associated with the hump component separated by a sum of two kinetic functions from the ON segment of a TEST-minus-CONTROL current trace (method 2), (b) the steeply voltage-dependent component separated from a Q-V plot of the total charge by fitting with a sum of two Boltzmann distribution functions (method 3), and (c) the sigmoidal component separated from the Q-V plot of the final OFF charge obtained with a two-pulse protocol (method 4). The steeply voltage-dependent components separated by all four methods are consistent with each other, and are therefore concluded to be equivalent to the same Q gamma component. The shortcomings of each separation method are critically discussed. Since each method has its own advantages and disadvantages, it is recommended that, as much as possible, Q gamma should be separated by more than one method to obtain more reliable results.

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Selected References

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  1. Adrian R. H., Almers W. Charge movement in the membrane of striated muscle. J Physiol. 1976 Jan;254(2):339–360. doi: 10.1113/jphysiol.1976.sp011235. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Adrian R. H., Chandler W. K., Rakowski R. F. Charge movement and mechanical repriming in skeletal muscle. J Physiol. 1976 Jan;254(2):361–388. doi: 10.1113/jphysiol.1976.sp011236. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Adrian R. H., Huang C. L. Experimental analysis of the relationship between charge movement components in skeletal muscle of Rana temporaria. J Physiol. 1984 Aug;353:419–434. doi: 10.1113/jphysiol.1984.sp015344. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Adrian R. H., Peres A. R. A gating signal for the potassium channel? Nature. 1977 Jun 30;267(5614):800–804. doi: 10.1038/267800a0. [DOI] [PubMed] [Google Scholar]
  5. Adrian R. H., Peres A. Charge movement and membrane capacity in frog muscle. J Physiol. 1979 Apr;289:83–97. doi: 10.1113/jphysiol.1979.sp012726. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Almers W., Best P. M. Effects of tetracaine on displacement currents and contraction of frog skeletal muscle. J Physiol. 1976 Nov;262(3):583–611. doi: 10.1113/jphysiol.1976.sp011611. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Almers W. Differential effects of tetracaine on delayed potassium channels and displacement currents in frog skeletal muscle. J Physiol. 1976 Nov;262(3):613–637. doi: 10.1113/jphysiol.1976.sp011612. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Baylor S. M., Chandler W. K., Marshall M. W. Sarcoplasmic reticulum calcium release in frog skeletal muscle fibres estimated from Arsenazo III calcium transients. J Physiol. 1983 Nov;344:625–666. doi: 10.1113/jphysiol.1983.sp014959. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Chandler W. K., Hui C. S. Membrane capacitance in frog cut twitch fibers mounted in a double vaseline-gap chamber. J Gen Physiol. 1990 Aug;96(2):225–256. doi: 10.1085/jgp.96.2.225. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Chandler W. K., Rakowski R. F., Schneider M. F. A non-linear voltage dependent charge movement in frog skeletal muscle. J Physiol. 1976 Jan;254(2):245–283. doi: 10.1113/jphysiol.1976.sp011232. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Chandler W. K., Rakowski R. F., Schneider M. F. Effects of glycerol treatment and maintained depolarization on charge movement in skeletal muscle. J Physiol. 1976 Jan;254(2):285–316. doi: 10.1113/jphysiol.1976.sp011233. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Chen W., Hui C. S. Differential blockage of charge movement components in frog cut twitch fibres by nifedipine. J Physiol. 1991 Dec;444:579–603. doi: 10.1113/jphysiol.1991.sp018895. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Chen W., Hui C. S. Existence of Q gamma in frog cut twitch fibers with little Q beta. Biophys J. 1991 Feb;59(2):503–507. doi: 10.1016/S0006-3495(91)82243-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Csernoch L., Huang C. L., Szucs G., Kovacs L. Differential effects of tetracaine on charge movements and Ca2+ signals in frog skeletal muscle. J Gen Physiol. 1988 Nov;92(5):601–612. doi: 10.1085/jgp.92.5.601. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Hollingworth S., Marshall M. W., Robson E. The effects of tetracaine on charge movement in fast twitch rat skeletal muscle fibres. J Physiol. 1990 Feb;421:633–644. doi: 10.1113/jphysiol.1990.sp017966. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Horowicz P., Schneider M. F. Membrane charge movement in contracting and non-contracting skeletal muscle fibres. J Physiol. 1981 May;314:565–593. doi: 10.1113/jphysiol.1981.sp013725. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Huang C. L., Peachey L. D. Anatomical distribution of voltage-dependent membrane capacitance in frog skeletal muscle fibers. J Gen Physiol. 1989 Mar;93(3):565–584. doi: 10.1085/jgp.93.3.565. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Huang C. L. Pharmacological separation of charge movement components in frog skeletal muscle. J Physiol. 1982 Mar;324:375–387. doi: 10.1113/jphysiol.1982.sp014118. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Huang C. L. The differential effects of twitch potentiators on charge movements in frog skeletal muscle. J Physiol. 1986 Nov;380:17–33. doi: 10.1113/jphysiol.1986.sp016269. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Huang C. L. Voltage-dependent block of charge movement components by nifedipine in frog skeletal muscle. J Gen Physiol. 1990 Sep;96(3):535–557. doi: 10.1085/jgp.96.3.535. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Hui C. S., Chandler W. K. Intramembranous charge movement in frog cut twitch fibers mounted in a double vaseline-gap chamber. J Gen Physiol. 1990 Aug;96(2):257–297. doi: 10.1085/jgp.96.2.257. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Hui C. S., Chandler W. K. Q beta and Q gamma components of intramembranous charge movement in frog cut twitch fibers. J Gen Physiol. 1991 Sep;98(3):429–464. doi: 10.1085/jgp.98.3.429. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Hui C. S., Chen W. Effects of conditioning depolarization and repetitive stimulation on Q beta and Q gamma charge components in frog cut twitch fibers. J Gen Physiol. 1992 Jun;99(6):1017–1043. doi: 10.1085/jgp.99.6.1017. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Hui C. S. Comparison of charge movement components in intact and cut twitch fibers of the frog. Effects of stretch and temperature. J Gen Physiol. 1991 Aug;98(2):287–314. doi: 10.1085/jgp.98.2.287. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Hui C. S. Differential properties of two charge components in frog skeletal muscle. J Physiol. 1983 Apr;337:531–552. doi: 10.1113/jphysiol.1983.sp014640. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Hui C. S. Factors affecting the appearance of the hump charge movement component in frog cut twitch fibers. J Gen Physiol. 1991 Aug;98(2):315–347. doi: 10.1085/jgp.98.2.315. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Hui C. S. Pharmacological dissection of charge movement in frog skeletal muscle fibers. Biophys J. 1982 Jul;39(1):119–122. doi: 10.1016/S0006-3495(82)84498-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Hui C. S. Pharmacological studies of charge movement in frog skeletal muscle. J Physiol. 1983 Apr;337:509–529. doi: 10.1113/jphysiol.1983.sp014639. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Irving M., Maylie J., Sizto N. L., Chandler W. K. Intrinsic optical and passive electrical properties of cut frog twitch fibers. J Gen Physiol. 1987 Jan;89(1):1–40. doi: 10.1085/jgp.89.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Kovacs L., Rios E., Schneider M. F. Measurement and modification of free calcium transients in frog skeletal muscle fibres by a metallochromic indicator dye. J Physiol. 1983 Oct;343:161–196. doi: 10.1113/jphysiol.1983.sp014887. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Lamb G. D. Components of charge movement in rabbit skeletal muscle: the effect of tetracaine and nifedipine. J Physiol. 1986 Jul;376:85–100. doi: 10.1113/jphysiol.1986.sp016143. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Maylie J., Irving M., Sizto N. L., Chandler W. K. Calcium signals recorded from cut frog twitch fibers containing antipyrylazo III. J Gen Physiol. 1987 Jan;89(1):83–143. doi: 10.1085/jgp.89.1.83. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Melzer W., Schneider M. F., Simon B. J., Szucs G. Intramembrane charge movement and calcium release in frog skeletal muscle. J Physiol. 1986 Apr;373:481–511. doi: 10.1113/jphysiol.1986.sp016059. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Rios E., Brum G. Involvement of dihydropyridine receptors in excitation-contraction coupling in skeletal muscle. Nature. 1987 Feb 19;325(6106):717–720. doi: 10.1038/325717a0. [DOI] [PubMed] [Google Scholar]
  35. Schneider M. F., Chandler W. K. Voltage dependent charge movement of skeletal muscle: a possible step in excitation-contraction coupling. Nature. 1973 Mar 23;242(5395):244–246. doi: 10.1038/242244a0. [DOI] [PubMed] [Google Scholar]
  36. Vergara J., Caputo C. Effects of tetracaine on charge movements and calcium signals in frog skeletal muscle fibers. Proc Natl Acad Sci U S A. 1983 Mar;80(5):1477–1481. doi: 10.1073/pnas.80.5.1477. [DOI] [PMC free article] [PubMed] [Google Scholar]

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