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Figure 4 | Molecular Pain

Figure 4

From: Ionic basis of a mechanotransduction current in adult rat dorsal root ganglion neurons

Figure 4

The mechanotransduction current can be carried and blocked by calcium and magnesium ions. (A) Mechanically activated current traces recorded from a 40-μm DRG neuronal soma when bath solution consisted of 100 mM CaCl2 (with HEPES, glucose, and sucrose) at membrane voltages of -112, -72, -32, +48, and +88 mV. Probe velocity was 3.4 mm/s. (B) Mean current-voltage relation in calcium chloride bath (closed circles). The mean amplitude of current seen in standard solutions at -70 mV, in the same cells using the same stimulus parameters, is indicated by the open circle. (C) Current traces recorded from a neuron (41-μm diameter) when bathed in 100 mM MgCl2 at membrane voltages ranging from -112 to +128 mV in steps of 40 mV. Probe velocity was 3.5 mm s-1. (D) Mean current-voltage relation for mechanotransduction currents in magnesium chloride bath (closed circles). The mean amplitude of current seen in standard solutions at -70 mV, in the same cells using the same stimulus parameters, is indicated by the open circle. (E) Amplitudes of mechanically activated current responses at -70 mV in otherwise standard external solution containing CaCl2 concentrations of 0.025 mM, 0.25 mM, 2.5 mM (standard), and 25 mM and no added MgCl2. All current amplitudes were normalized to the size of the current in the same cell (n = 6–8 cells) using the same stimulus parameters in the standard bath solution with 2.5 mM CaCl2 and 0.6 mM MgCl2 at -70 mV. (F) Amplitudes of responses at -70 mV in bath solutions all containing 0.025 mM CaCl2 but with MgCl2 concentrations of 0.06 mM, 0.6 mM (standard), and 6 mM. At the left is the value from panel E for 0.025 mM CaCl2 and 0 MgCl2 for reference. All current amplitudes were normalized to the size of the current in the same cell (n = 3–5 cells) using the same stimulus parameters in the standard bath solution with 2.5 mM CaCl2 and 0.6 mM MgCl2 at -70 mV.

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