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. 2007 Oct 24;27(43):11560–11572. doi: 10.1523/JNEUROSCI.2147-07.2007

Figure 3.

Figure 3.

Mechanism of direct action of mGluRs on MCH neurons. A, DHPG shows no clear change of the voltage responses after hyperpolarizing current steps (see protocol at the bottom). B, The current–voltage relationship in the absence (white circles) or presence (filled circles) of DHPG. C, DHPG (100 μm) actions on the membrane potential in control condition (control; resting membrane potential, −61.6 mV), when Na+ is replaced by Tris (Tris; resting membrane potential, −65.7 mV), in the presence of nickel (nickel; resting membrane potential, −60.8 mV), with BAPTA in the pipette solution (BAPTA; resting membrane potential, −62.3 mV), in Ca2+-free extracellular solution (Ca-free; resting membrane potential, −61.9 mV), or in the presence of the Na+/Ca2+ exchanger blocker KB-R9743 (KB-R9743; resting membrane potential, −60.7 mV). TTX (1 μm) is added to the bath. D, Mean membrane depolarization by DHPG obtained from C. E, DHPG induces an inward current at voltages between −120 mV and +40 mV. In the presence of TTX, CdCl2, TEA, and with Cs intracellular solution, the DHPG-induced current shows a reversal potential consistent with a Na+/Ca2+ exchanger conductance. F, DHPG reduces whole-cell K+ current, and potassium channel blockers TEA and CsCl block this effect. G, Time course of DHPG effect on K+ current (IK) in the same MCH cell as in F. H, Mean amplitude of K+ current (IK) in control conditions (control), in the presence of DHPG (DHPG), with TEA and CsCl in the bath (after washout of DHPG, TEA plus CsCl), and further application of DHPG (TEA plus CsCl plus DHPG). Ctrl, Control. I, DHPG decreases Ca2+ current. External calcium is replaced by barium in all of these experiments. Bath application of CdCl2 abolished the barium current (IBa). J, Mean effect of DHPG on the amplitude of IBa. Ctrl, Control. K, The effect of DHPG on IBa during a voltage ramp from −60 to +40 mV. The top trace shows the subtracted current. The inset shows the overlay of scaled subtracted current and the control current. L, The mean percentage inhibition of barium current by DHPG was plotted against membrane potential. The number of cells is shown in parentheses. Error bars indicate SEM. The asterisk indicates statistically significant.