Figure 5

A selective agonist of S1PR₃, CYM-5541, sensitizes AP firing. (A) Left panel illustrates a representative recording where the ramp evoked 3 APs under control conditions; right panel shows that after a 10-min exposure to 10 μM CYM-5441, 11 APs were generated. The dotted line indicates 0 mV. (B) the time- and concentration-dependence of CYM-5541 on the number of evoked APs over a 10-min recording period. For 100 nM, there was no effect on the number of evoked APs (n = 5, P = 0.80 RM ANOVA); for 1 μM, the increase in AP number at 6 and 10 min was significantly different than the control (n = 6, P = 0.002 RM ANOVA Friedman test on ranks); for 10 μM, the increase at 6 and 10 min was significantly different than the control (n = 6, P < 0.001 Kruskal-Wallis ANOVA on ranks Dunn’s test); for the 1 μM W146 + 10 μM CYM-5541, the increase at 6 and 10 min was significantly different than the control (n = 7 for control, 2 and 6 min, n = 6 for 10 min, P < 0.001 ANOVA Holm-Sidak all-pairs test). The AP values for 10 μM CYM-5541 and 1 μM W146 + 10 μM CYM-5541 at either 6 or 10 min were not different (P > 0.05 ANOVA). (C) Concentration dependence for the normalized fold increase in the number of APs measured after a 10-min exposure to CYM-5541. (D) Recording of membrane potential where the left panel shows the control condition; the right panel shows exposure to 30 μM CYM-5541 (30 to 150 s represented by the bar). (E) Depolarization produced by 30 μM SEW2871 (application 30 to 150 s). Recordings were acquired at 5 kHz; traces are reproduced at 0.5 kHz. Scale bars apply to all three panels. AP - action potential, Cont - control.