Table 1.
Comparison of the properties of highly selective and nonselective channels
| Highly Selective | Nonselective | |
|---|---|---|
| Na/K selectivity (48, 61) | >40 | 1.1 |
| Unit conductance, pS (48, 50, 61) | 6 | 21 |
| Amiloride Ki, nM (48, 82) | 38 | 2,300 |
| Increased cellular cAMP or β-adrenergic stimulation (15, 22) |
Channel surface density increases | Po increases |
| Increased cGMP or nitric oxide (46) |
Po decreases | Po decreases |
| PKC activation (16, 23) | Po decreases and surface density decreases | Channel surface density increases |
| Increased intracellular Ca2+ (15) | No effect | Po increases |
| Purinergic stimulation (18, 59, 70, 78) | Po decreases | Po increases |
| Dopaminergic stimulation (41, 43) |
Po increases | No effect |
| Superoxide production (42) | Po increases | Channel surface density increases |
| Hypoxia (48) | Channel surface density decreases | Channel surface density increases |
Po, channel open probability; Ki, inhibitory constant, i.e., the dose that reduces open probability by 50%.