Effects of hemichannel blockers on VG outward currents and ATP secretion in taste cells of the type II. (A) Representative recordings of VG currents in control (top panels) and after a 10-min incubation with the Cx mimetic peptide 43GAP26 (500 μM; n = 21), 3 mM octanol (n = 11), Px mimetic peptide 10Px1 (300 μM; n = 9), and 20 μM carbenoxolone (n = 7) in the bath. The traces presented in different panels were obtained from four different cells, which were held at −70 mV and polarized by 100-ms voltage pulses between −100 and 50 mV with the 10-mV decrement, as shown in the top left panel. (B) VG currents on the 100-ms depolarization to 20 mV recorded in control cells (n = 32) and in cells preincubated either with 10Px1 (300 μM; n = 7) or with 43GAP26 (300 μM; n = 12) for 30 min. The difference between the averaged current magnitudes in control and in the presence of 10Px1 is not statistically significant at the P < 0.05 confidence level. (C) Evolution of steady-state VG currents measured in the end of voltage pulses (•, ▾) and ATP sensor responses (○, ▵) after the addition of 43GAP26 (300 μM; •, ○; n = 14), and Px1 mimetic peptide 10Px1 (300 μM; ▾, ▵; n = 9) to the bath at t = 0. The VG currents were elicited by the 100-ms depolarization of taste cells from −70 to 0 mV that did not stimulate detectable ATP efflux. The secretion of ATP was elicited by the 2-s depolarization of taste cells to 10 mV. In B and C, the data are presented as a mean ± SD. In all cases, VG currents were recorded with 140 mM CsCl in the recording pipette and 140 mM NaCl in the bath using the perforated patch approach.
