A Channel View at Ca Inactivation
Ca currents rise and fall during a step change in potential (see 1–3) and these changes are termed activation and inactivation. Activation is voltage-dependent but the voltage dependence of inactivation has been recently contested (4–8). The occurrence of inactivation may be exaggerated because outward K currents, particularly Ca-activated currents, and other nonspecific outward currents have time courses that coincide with inactivation. The process is greatly reduced when outward currents are minimized. Tail currents measured at return potentials where outward currents should be negligible have envelopes that follow the rise and fall of Ica and the result is readily taken as evidence of inactivation of Ica (9, see also 10).
KeywordsSingle Channel Outward Current Calcium Current Cell Current Dependent Inactivation
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- 11.Standen NB, Stanfield PR: A binding-site model for calcium channel inactivation that depends on calcium entry. Proc. R. Soc. (Lond.) B217, 101–110, 1982.Google Scholar
- 21.Lux HD: Observations on single Ca channels. In: B Sakmann and E Neher (eds) Single-channel recording. Plenum Publ. Corp., New York, 1983, pp 437-449.Google Scholar
- 22.Colquhoun D, Sigworth FJ: Fitting and statistical analysis of single-channel recordings. In: B Sakmann and E Neher (eds) Single-channel recording. Plenum Publ. Corp., New York, 1983, pp 191–263.Google Scholar