Fig. 9.
Ba2+ reduces the effects of dopamine on inhibitory, but not excitatory, synaptic transmission.A, Traces (top) were taken from the example experiment (middle) at the times indicated. Dopamine (75 μm) was applied to pharmacologically isolated IPSPs in cells held at 0 mV, and then reapplied in the presence of BaCl2 (1 mm). The summary graph (bottom, n = 5) compares the dopamine-induced depression of IPSPs in the absence and presence of Ba2+. B, Traces of reversed EPSPs (top) were taken from the example experiment (middle) at the times indicated. The effects of dopamine (75 μm) on EPSPs were examined first in the absence and then in the presence of Ba2+. The cell was held at +25 mV in the presence of d-APV (50 μm) and picrotoxin (50 mm). The summary graph (bottom, n = 5) compares the dopamine-induced depression of EPSPs in the absence and presence of Ba2+.