Figure 6. D₃- but not D₁-like dopamine agonists evoke activity in IC neurones.

A, each panel shows plots of holding current (ordinate) required to hold IC neurones at -80 mV against the time (abscissae) after drug exposure (> 5 min) for 3 neurones exposed tothe D₃-selective compound PD 128907 (300 nm; a) and3 neurones (different to those in a; superimposed on a single graph) exposed to 10 μm SKF-38393, a D₁ agonist (b). B, a direct comparison of the effects of 10 μm SKF-38393 and 300 nm PD 128907 in one neurone (not included in the experiments of A); the traces are membrane currents driven by 25 mV hyperpolarizing steps from -80 mV before, during (marked SKF and PD) and after exposure to the drug. SKF-38393 induced no systematic response but PD 128907 caused a 2 nA inward current which is not shown. All the data were from slices bathed in ACSF containing 0.5 μm TTX and 1 mm Ba²⁺.