Kinetics of calcium inward current activation

Calcium Channel

“…The displacement current, which probably corresponds to the movement of the gating particles of the Na channel in response to sudden changes in membrane potential, was fi rst observed in squid axon (Arm strong & Bezanilla 1973. Similar currents associated with Ca channels have been reported in Aplysia (Adams & Gage 1976, 1979b and Helix neurons (Kostyuk et al 1977a(Kostyuk et al , 1979. Both groups de tected the displacement currents by methods similar to that used fo r the Na channel.…”

Two types of low‐voltage‐activated Ca2+ channels in neurones of rat laterodorsal thalamic nucleus.

“…C, LVA Ca?+ current for P17 neurones after 20 min application of 100 #M nifedipine (nifedipine-insensitive current & Shakhovalov, 1979;Kay & Wong, 1987). The equation used for fitting the LVA Ca2+ current (ICa) was:…”

Sodium and calcium channels in bovine chromaffin cells

“…The models previously proposed to account for the kinetic properties of Ca2+ currents all assume that the opening ofa Ca2+ channel is the result of the simultaneous activation of a independent subunits, with a = 1 , a = 2 (Kostyuk & Krishtal, 1977; Kostyuk, Krishtal, Pidoplichko & Shakhovalov, 1979), or a = 5 (Llinas et al 1981) (for further references see Hagiwara & Byerly, 1981) According to these models, tail current measured at very negative holding potentials should display a single exponential component with a time constant r/a., where r is the activation time constant of one subunit. In addition, a second component having a time constant of r/(a-1) should appear for more depolarized holding potentials.…”