Fig. 5.
σ1R modulates kinetics of VGCC in axotomized animals. After whole-cell configuration, the current-voltage relationship (I-V), voltage-dependent activation, and steady-state inactivation of the ICa were measured as described in Fig. 4 using Ba2+ as charge carrier in SNL L5 DRG sensory neurons. (A) Average inward current density (pA/pF) against I-V relationship elicited by PTZ (50 μM) and DTG (100 μM) was fit to a single Boltzmann function (see Materials and Methods). (B) Voltage-dependent activation of VGCC was derived from the I-V curve. (C) In steady-state inactivation, V1/2 was shifted toward a hyperpolarization direction. (D) Sample traces showed that both PTZ and DTG administration decreased slow inactivation constant (τ2). Inset figures revealed summary data of maximal conductance (Gmax; A), voltage at which current is half-maximal (V1/2; B and C), and inactivation constant (τ; D). Mean ± S.E.M.; number in bars represents the sample size; *P < 0.05; **P < 0.01; ***P < 0.001. BL, baseline.