FIG. 3.

Depolarization-induced exocytosis is impaired in β-cells lacking ABCA1. A: β-Cell membrane capacitance (C_m) and voltage-dependent Ca²⁺ currents (I_Ca) in response to a single 500-ms depolarization. B: The average exocytotic response, normalized to initial cell size (n = 40–58). C: FM1-43 destaining in response to 30 mmol/L KCl in ABCA1^+/+ (n = 23, ■) and ABCA1^−P/−P (n = 24, □) β-cells. AU, arbitrary unit. D: Capacitance measurements after a series of membrane depolarizations of progressively increasing duration. E: The average responses of ABCA1^+/+ (n = 40, ■) and ABCA1^−P/−P (n = 58, □) β-cells. *P < 0.05, **P < 0.01, and ***P < 0.001 compared with controls.