Figure 7. InsP₃-induced changes in [Ca²⁺]_L determined in the presence of oxidizable mitochondrial substrates.

Preparations were challenged by step-wise increases in [InsP₃] applied in ICM-citrate (A), ICM-succinate (B), or ICM-pyruvate/malate (C). Under all these conditions, increasing [InsP₃] caused graded declines in [Ca²⁺]_L accompanied by an increase in the frequency of [Ca²⁺]_L oscillations. To avoid changes in the free Ca²⁺ concentration of the intracellular-like media resulting potentially from the addition of mitochondrial substrates, these experiments were performed in ICM supplemented with 100 μM EGTA.