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. 2017 Feb 1;7:41782. doi: 10.1038/srep41782

Figure 1. Functional characterization of Am-CaV3 in Xenopus oocytes.

Figure 1

(a) Ba2+ Current traces recorded from oocytes expressing Am-CaV3. Holding potential: −100 mV, Step potential −30 mV, duration: 150 ms. (b) Averaged activation and inactivation curves recorded from Am-CaV3-injected oocytes. The inactivation curves were obtained using 2.5 s conditioning potentials from −100 to various potentials (10 mV increment) followed by a subsequent test pulse to −30 mV. Voltages for half-activation (Vact): −47 ± 1 mV, activation slope: 6.7 ± 0.3 mV, voltage for half-inactivation (Vinact): −66 ± 1 mV, inactivation slope: 3.5 ± 0.2 mV, percentage of non-inactivating current: 5 ± 1% (n = 12). The window current, is underlined as a dotted surface. (c) Current inactivation time-course was fitted at each potential using a mono-exponential decay with a time constant Tau. The voltage-dependence of Tau displayed an exponential decrease with an e-fold decrease (Vdep.) every 7.9 ± 0.4 mV (n = 10). (d) Increase in Ba2+ current amplitudes recorded on oocytes expressing CaV3 Ca2+ channel produced by the coexpression of the CaVβ subunit20. Currents were normalized to the current amplitude of Am-CaV3 without CaVβ (n = 4). (e) Pharmacological profile of Am- CaV3 Ca2+ channels defined by the response to several calcium antagonists, insecticides and toxins. The residual currents in response to these antagonists are shown relative to the current recorded in control condition. Pe: permethrin 50 μM; Al: allethrin 50 μM: Iv: ivermectine 10 μM; Pi: picrotoxin 10 μM; Fi: fipronil 10 μM; Cl: clothianidine 10 μM; Ch: Chlorantraniliprole 10 μM; Mi: mibefradil 10 μM; NN: NNC 55-0396 10 μM; TT: TTA-A2 10 μM; Ni: nifedipine: 10 μM; BK: bay-k 8644 10 μM; Ve: verapamil 10 μM; Di: diltiazem 10 μM; Am: amiloride 1 mM; At: atrachotoxin 10 μM; Ag: w-aga-IV-A 10 μM; SN: SNX 482 10 μM; Ni: nickel chloride 0.12 mM, CdCl2: cadmium chloride 0.2 mM. (f) Dose-response curve of mibefradil on Am-CaV3 current amplitude. Continuous line is the best fit using the Hill equation (n = 10). The effect of mibefradil (10 μM, holding potential of −100 mV and depolarization to −30 mV, trace marked “M”) is shown on the inset. Rel cur: currents normalized to the current amplitude recorded in the absence of mibefradil.