The glycinergic components of the serotonin-evoked IPSCs account for their slower decay kinetics.A, S-IPSCs and the GABAergic component of L-IPSCs have the same decay time course. Averaged S-IPSCs and L-IPSCs_GABA recorded from the same cell in control conditions and after addition of serotonin and strychnine (1 μm) are plotted on the left. Biexponential functions fitting the decay of the IPSCs are displayed (solid lines). The time constants are 14 and 52 msec for the S-IPSCs and 20 and 57 msec for the L-IPSCs_GABA. The same IPSCs are scaled to their peak on the right. B, The time constants of decay of S-IPSCs and L-IPSCs_GABA obtained in the same six cells are plotted against each other. The slopes of the linear regressions (solid lines) are 1.16 and 0.86 for the fast (circles) and slow (triangles) components, respectively.C, The glycinergic component of L-IPSCs has a slower decay than S-IPSCs have. Averaged S-IPSCs and L-IPSCs_Glyrecorded from the same cell in control conditions and after addition of serotonin and gabazine (30 μm) are plotted on theleft. The sum of two exponential functions of time constants of 14 and 40 msec is superimposed on the decay of the S-IPSC, whereas the decay of the L-IPSCs_Gly is fitted by a monoexponential function with a time constant of 45 msec. The same IPSCs are scaled to their peak on the right.D, A plot the same as that inB is shown. In all cells the decay of the mean glycinergic IPSCs was appropriately fitted by a single-exponential function, and the single decay time constant of glycinergic IPSCs is compared with both time constants of control IPSCs. The slope of the linear regressions are 2.3 and 0.68.