Figure 6.

Effects of paeonol on steady-state outward currents of the RP4 neuron in Na⁺-free and Co²⁺-substituted Ca²⁺-free saline in the absence and presence of TEA (50 mmol/L). A and B were recorded from two different RP4 neurons. Currents were elicited by 500-ms-long command steps from holding potentials of -60 mV to test potentials (ie, from -70 to 50 mV at intervals of 10 mV). A1: Control; steady-state outward currents of the RP4 neuron in Na⁺-free and Co²⁺-substituted Ca²⁺-free saline. A2, A3 and A4: 20 min after administration of paeonol 150 μmol/L, 500 μmol/L and 1.5 mmol/L, respectively. B1: Steady-state outward currents of the RP4 neuron in TEA (50 mmol/L)-containing Na⁺-free and Co²⁺-substituted Ca²⁺-free saline. B2: 20 min after administration of paeonol (500 μmol/L), from B1. C1 and C2: Effects of paeonol (500 μmol/L and 1.5 mmol/L) on the current-voltage relationships of the steady-state outward currents measured at 500 ms of the RP4 neuron in Co²⁺-substituted Ca²⁺-free and Na⁺-free solution, respectively. The closed circle (•) in C1 and C2 represents the I–V relationship before paeonol (500 μmol/L) application. The open circle (○) in C1 and closed square (▪) in C2 represent the I–V relationship at 20 min after paeonol (500 μmol/L and 1.5 mmol/L) application, respectively (^bP<0.05 vs control, n=5). C3: Effects of paeonol (500 μmol/L) on the current-voltage relationships of the steady-state outward currents measured at 500 ms of the RP4 neuron in TEA (50 mmol/L)-containing Co²⁺-substituted Ca²⁺-free and Na⁺-free solution. The closed circle (•) and open circle (○) in C3 represent the I–V relationship before and at 20 min after paeonol (500 μmol/L) application, respectively (^bP<0.05 vs the data in TEA 50 mmol/L). However, when neurons were pretreated with TEA, paeonol was less effective at decreasing the outward current.