Pharmacological profile of the inward currents.A, The dihydropyridine antagonist isradipine (10 μm) blocks the ICa elicited by a depolarizing step to −30 mV (Vh, −70 mV). Each trace is the average of 24 records.B, ICa was increased after bath application of Bay K 8644 (10 μm), a specific agonist of L-type Ca2+ channels. Note the increase in amplitude and slower decay of the tail upon return to the holding potential of −70 mV. Each trace is the average of 36 records. C, Evidence for the activation of reciprocal synapses. Current fluctuations superimposed upon depolarization-evokedICa in control external saline (top trace) and after bath perfusion with antagonists of GABA and glycine receptors (bottom trace). Each current record is the result of a single depolarizing pulse to 0 mV. Internal solution for A–C was CsGlu.