Figure 6.

Effect of L-loop on depolarization-evoked exocytosis in β-cells. (A) Changes in membrane capacitance (ΔC_m) elicited by 500 ms of depolarization under control conditions and after inclusion of the peptides in the pipette solution as indicated. The dotted horizontal line indicates the prestimulatory capacitance level. (B) Histograms summarizing the Lc_753–893 and Lc_753–779 effects on depolarization-induced exocytosis. Values are mean values ± SEM of 16 (control and Lc_753–893) and six experiments (Lc_753–779), respectively. Statistical significance was calculated by using Student’s t test and the asterisks indicate P < 0.001. (C) Ca²⁺ currents elicited by 300-ms depolarization pulses to the indicated potentials in the absence (▾) or presence (○) of Lc_753–893. (D) Voltage dependence of integrated Ca²⁺ currents (Qca). The traces represent mean values ± SEM of seven and six experiments in the absence (■ solid line) or presence (○ dotted line) of Lc_753–893, respectively. (E) Ca²⁺ currents recorded in response to +10 mV (to facilitate analysis of inactivation) 30 s (black) and 4 min (gray) after establishment of the whole cell configuration.