Figure 2. Effects of the TCA cycle intermediate succinate on [Ca²⁺]_m and insulin secretion in permeabilised INS-1 cells.

Cells expressing the Ca²⁺-sensitive photoprotein aequorin targeted to the mitochondria were permeabilised with α-toxin and perifused with an intracellular buffer containing 500 nM free Ca²⁺ and high ATP (10 mm). The effects of succinate (Suc) on [Ca²⁺]_m (A) and insulin secretion (B) were measured simultaneously. Influx of Ca²⁺ into the mitochondria via the uniporter was blocked using Ruthenium Red (RR) before the addition of Suc during the measurement of [Ca²⁺]_m (C) and insulin secretion (D). Modified with permission from Maechler et al. (1997).