Calcium Current Inactivation Rather than Pool Depletion Explains Reduced Exocytotic Rate with Prolonged Stimulation in Insulin-Secreting INS-1 832/13 Cells
Figure 3
Demonstration of the double-pulse protocol.
Single cells were depolarized from a holding potential of −70 mV to 0 mV during 50 ms. This was followed by a resting period of 100 ms and a second 50-ms depolarization from −70 mv to 0 mV (top trace). The evoked Ca2+ currents were measured and the charges for the first (Q1) and second (Q2) pulses were estimated (middle trace). In addition, the increases in membrane capacitance evoked by the first (ΔCm1) and second (ΔCm2) depolarizations were measured.