Fig. 2.

Isolation of amiloride-sensitive transient calcium currents by prepulse inactivation. A: transient (T) current evoked by a test step to −5 mV from a prepulse of −80 mV (PP −80) is blocked by prepulse to −10 mV (PP −10). In contrast, the sustained current (S) is similar in size with prepulses to −10 mV and −80 mV. B: perfusion of the recording chamber with 1 mM amiloride for 10 min reduced the size of the transient current but did not alter the sustained current, confirming that the currents sensitive to prepulse inactivation are inhibited by amiloride. C: magnitude of the transient calcium current, evaluated using the prepulse protocol, is significantly reduced by 1 mM amiloride (***P < 0.001, t-test unpaired). D: magnitude of sustained calcium current was not altered by amiloride. Each bar indicates the means and SE; n = 17 for 1.8 mM Ca²⁺ and n = 11 for 1.8 mM Ca²⁺ + 1 mM amiloride. Whole cell calcium currents were isolated with TTX, PTX, d-tubocurarine, TEA, and internal cesium.