Fig. 8.

Effect of dopamine and dopamine antagonists on the ability of picrotoxin to cause slow enhancement of glycinergic IPSCs. Light stimuli and recording conditions are as described in Figure 1.A, Addition of 20 μm dopamine caused a rapid increase in IPSC amplitude within 2 min (DOP 2′), but there was no further increase after 15 additional minutes in dopamine (DOP 17′). The initial enhancement of the IPSC by dopamine was seen in only two of the four cells tested; in all four cells the mean enhancement was 1.13 (± 0.32)-fold (p = 0.65). After 18 min in dopamine, addition of 150 μm picrotoxin caused an immediate strong reduction in the IPSC (DOP + PTX 2′). In the continued presence of PTX the IPSC was slowly enhanced (DOP + PTX 17′). The mean enhancement by PTX was 4.02 (± 1.48)-fold (p = 0.02;n = 4). B, Addition of 15 μm SCH23390 and 150 μmPTXcaused an immediate reduction of the IPSC (SCH + PTX 2′), but in the continued presence of PTX andSCH the response slowly became enhanced (SCH + PTX 17′). In the five cells tested, the maximum enhancement byPTX in the presence of SCH was 4.42 (± 1.24)-fold (p = 0.02). In bothA and B the enhanced IPSC inPTX was completely blocked by 2 μmstrychnine in all cells (data not shown).