a, Representative traces of eIPSC recorded at a holding potential of −90 mV before and after incubation with different DHPs: Nifedipine (Nif), Nitrendipine (Nitren) and Bay-K. b, Bar graph showing that both L-type VGCC antagonists Nif (3 μM) or Nitren (10 μM) caused a significant increase in m whereas the agonist Bay-K (10 μM) caused a significant reduction in this parameter. c, Bar graph illustrating the effects of DHPs on the amplitude of sIPSC. Nifedipine at a concentration of 3 μM had no effects on this parameter. Both Nitrendipine and Bay-K which were used at higher concentrations (10 μM), slightly but significantly, reduced sIPSC amplitude. d, Representative traces showing the average of 10–15 sIPSC before and after incubation with DHPs.