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Comment
. 2009 Sep;134(3):259-61; author reply 263-5.
doi: 10.1085/jgp.200910222.

About a new method to measure fractional Ca2+ currents through ligand-gated ion channels

Sergio Fucile, Francesca Grassi
Comment

About a new method to measure fractional Ca2+ currents through ligand-gated ion channels

Sergio Fucile et al. J Gen Physiol. 2009 Sep.
No abstract available

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Figures

Figure 1.
Figure 1.
Decomposition of experimental I-V curves for the total current into the components carried by Ca2+ and by all other ions, assuming an ohmic behavior of all currents. In both A and B, ECa2+ = 86 mV, calculated using the Nernst equations with [Ca2+]o = 100 mM and [Ca2+]i = 0.1 mM (i.e., 0.1% of the main cation, a reasonable upper bound for the value). Total current (itotal; solid lines) has a slope conductance of 30.6 pS (as in Fig. 15 of Elenes et al., 2009). (A) With [Ca2+]o = 100 mM and [Na+]o = 150 mM, itotal has a reversal potential of +18 mV and an amplitude of −0.6 pA at 0 mV (Elenes et al., 2009). The pure Ca2+ current (iCa2+; dotted line) is the line that passes through this experimental point and is 0 at ECa2+, which yields a slope conductance of 7 pS. The lumped current carried by all other ions (iNa+−Mg2+; dashed line) has been calculated by subtraction (itotal− iCa2+) and reverts at 0 mV as expected. (B) When NaCl is not included into the external solution, we can estimate that [Na+]o = 0.1 mM and the Nernst equation yields ENa+−Mg2+ = −180 mV (neglecting Mg2+ for the sake of simplicity). We assumed that itotal has a reversal potential of −10 mV (Villarroel and Sakmann, 1996). iCa2+ was calculated imposing iCa2+ = itotal at −180 mV and iCa2+ = 0 at 86 mV, and has a slope conductance of 20 pS. iNa+−Mg2+ reverts at ENa+−Mg2+ = −180 mV.
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References

    1. Adams D.J., Dwyer T.M., Hille B. 1980. The permeability of endplate channels to monovalent and divalent metal cations.J. Gen. Physiol. 75:493–510 - PMC - PubMed
    1. Bregestovski P.D., Miledi R., Parker I. 1979. Calcium conductance of acetylcholine-induced endplate channels.Nature. 279:638–639 - PubMed
    1. Decker E.R., Dani J.A. 1990. Calcium permeability of the nicotinic acetylcholine receptor: the single-channel calcium influx is significant.J. Neurosci. 10:3413–3420 - PMC - PubMed
    1. Elenes S., Decker M., Cymes G.D., Grosman C. 2009. Decremental response to high-frequency trains of acetylcholine pulses but unaltered fractional Ca2+ currents in a panel of “slow-channel syndrome” nicotinic receptor mutants.J. Gen. Physiol. 133:151–169 - PMC - PubMed
    1. Fucile S., Sucapane A., Grassi F., Eusebi F., Engel A.G. 2006. The human adult subtype ACh receptor channel has high Ca2+ permeability and predisposes to endplate Ca2+ overloading.J. Physiol. 573:35–43 - PMC - PubMed