Fig. 5.

A high concentration of either CCh or ACPD prevented the other from enhancing DSI and reducing eIPSC amplitude.A, ACPD (50 μm), which normally reduces eIPSC amplitude and occludes DSI at this concentration, did not affect DSI or eIPSC when applied with 25 μm CCh. Note that 50 μm ACPD had little effect on either eIPSC or sIPSC.B, In this cell, only sIPSCs were measured. DSI and eIPSC amplitudes were unaffected by 50 μm ACPD in the presence of 25 μm CCh. Ca²⁺ current and associated transient current were blanked for clarity. For clear comparison of DSI, a fast inward current activated by depolarization was subtracted from the baseline. The two DSI trials in each column are consecutive. C, In this cell, 50 μm ACPD was applied before 1 μm CCh. CCh slightly enhanced DSI but had no effect on eIPSC amplitude. D, Group data of ΔDSI. When 25 μm CCh was applied first (open bars), 50 μm ACPD had no effect on DSI of eIPSC (n = 5; paired t test;p > 0.5) or DSI of sIPSC (n = 7; paired t test; p > 0.5). When 50 μm ACPD was applied first (filled bar), 1 μm CCh slightly increased DSI of eIPSC, but it was not significant (n = 5; pairedt test; p > 0.1). In the experiments in which CCh was applied first, both sIPSC and eIPSC were measured in four cells, only sIPSC was measured in three cells, and only eIPSC was measured in one cell. E, When 25 μm CCh was applied first (open bars), 50 μm ACPD had no effect on amplitude of eIPSC (n = 5; paired t test;p > 0.1) or charge of sIPSC (n= 7; paired t test; p > 0.5). When 50 μm ACPD was applied first (filled bar), 1 μm CCh did not change the amplitude of eIPSC (n = 5; paired t test;p > 0.1). Charge carried by sIPSC was measured by integrating the area under sIPSC for 20 sec before and 16 sec after the 0 mV pulse. “Charge per second” was used as a magnitude of sIPSC.