Xanthurenic Acid Binds to Neuronal G-Protein-Coupled Receptors That Secondarily Activate Cationic Channels in the Cell Line NCB-20
Figure 5
Whole cell recording of XA responses from differentiated NCB-20 cells.
A and B: Current traces recorded in conditions of high (A) or low (B) cytoplasmic chloride ([Cl]i) concentrations. XA was applied to the recorded cells as indicated by the horizontal bars. C: Mean I–V relationships obtained in conditions of low (filled circles) or high (open circles) [Cl]i (5 cells in each condition). The dashed and continuous lines are the zero current level and linear regression to the data points respectively. Note that the reversal potential of XA responses did not change (−4.8 and −4.4 mV) with cellular chloride activities and was close to the cationic reversal potential which had a value of −0.9 and 0.4 mV in conditions of high and low cellular Cl concentrations respectively. D: mean cellular conductances activated by XA (20–30 µM) in high (black bar) and low (white bar) Cl concentrations respectively (mean±SEM, n = 7 cells). E: Dose-response relationship of XA. The continuous curve is the optimized Hill equation to the data points. Optimization parameters were EC50 = 11.7 µM, maximal conductance = 12.5 nS and Hill coefficient = 3.5.