Po | n | ||
---|---|---|---|
A | Control (20–100 μM Ca2+) | 0.47 ± 0.04 | 9 |
0.3 mM Suramin | 0.72 ± 0.03 | 9 | |
0.6 mM Suramin | 0.82 ± 0.04 | 6 | |
0.9 mM Suramin | 0.87 ± 0.01 | 6 | |
B | Control (50–100 μM Ca2+) | 0.51 ± 0.05 | 5 |
Control (0.6 μM Ca2+) | 0.003 ± 0.001 | 5 | |
1.2 mM Suramin | 0.050 ± 0.020 | 4 | |
C | Control (50–100 μM Ca2+) | 0.54 ± 0.02 | 6 |
Control (0.05 μM Ca2+) | 0.0008 ± 0.0004 | 6 | |
1.2 mM Suramin | 0.018 ± 0.004 | 6 | |
1.2 mM Suramin + 80 μM 4-CMPS | 0.81 ± 0.03 | 3 |
Single-channel currents were recorded at 0 mV holding potential (A) or+20 mV holding potential (B, C) with 480 mM/50 mM CsCl (cis/trans) and Ca2+ as indicated. Control and test records are from the same channel. Suramin was added to the cis side. A, activation of single channel current by 20 to 100 μM Ca2+ and 0.3, 0.6, and 0.9 mM suramin added sequentially to the cis side to give the indicated final concentration. Significantly different (P = 0.05), control vs. 0.3, 0.6, and 0.9 mM suramin; 0.3 mM suramin vs. 0.9 mM suramin (ANOVA). B, activation of single channel current by 1.2 mM suramin at 0.6 μM Ca2+ (cis). Control (0.6 μM Ca2+) vs. suramin (at 0.6 μM Ca2+) was significantly different (P = 0.03; t test). C, activation of single channel current by 1.2 mM suramin and 1.2 mM suramin plus 80 μM 4-CMPS at 0.05 μM Ca2+ (cis). Significantly different (P = 0.000001): Control (0.05 μM Ca) vs. suramin or suramin plus 4-CMPS (ANOVA). Values are presented as mean ± S.E.M. for the number of experiments (n).