mGluR7 expression in rat SCG neurons. A, Time course of calcium current amplitude during a test pulse to +10 mV (measured at 10 msec after the start of the step) in a rat SCG neuron expressing mGluR7. Application of 30 μM, 300 μM, and 1 mM L-AP4 at the indicated times produced a rapid and reversible inhibition of the current. Sample control (☆) and inhibited (★) current traces are shown in the inset. B, Average responses (±SEM) to a range of [L-AP4] from neurons expressing mGluR7 (■), and to 1 mM L-AP4 in control, uninjected cells (♢). Solid line represents a fit to the Hill equation, revealing an IC50 value of approximately 170 μM.