Table 2.
Effect of Ca2+ Channel Antagonists
| Current Clamp
|
Voltage Clamp
|
||||
|---|---|---|---|---|---|
| n | APdur50, ms | AHPampl, mV | Ipeak Inward, pA/pF | Ipeak Outward, pA/pF | |
| Control | 9 | 3.4 ± 0.7 | −17.5 ± 1.4 | −239.5 ± 49.2 | 269.3 ± 38.0 |
| Blockade | 9 | 5.5 ± 1.3* | −12.2 ± 1.6* | −126.9 ± 26.6* | 147.5 ± 27.5* |
Ca2+ channel antagonists mimic injury effect. Blockade with specific high voltage-activated Ca2+ channels prolonged action potential (AP) duration and decreased afterhyperpolarization (AHP) amplitude in current clamp mode, whereas peak inward and outward currents were decreased in the same cell in voltage clamp mode.
*
P ≤ 0.01 vs. control, paired t test.
AHPampl = AHP amplitude; APdur50 = AP duration at 50%; Ipeak Inward, Outward = peak inward and outward voltage clamped currents in response to AP waveform from same cell.