Figure 4.
mPTP open probability decreases during cardiac development
The calcium retention capacity (CRC) is a measure of mPTP. Mitochondria are exposed to pulses of calcium in the presence of arsenazo III in the solution, which fluoresces upon the binding of calcium. With each pulse, fluorescence increases and then decreases as mitochondria sequester the calcium until the calcium concentration in the mitochondrial matrix rises to a level that opens the mPTP (the CRC [nmol Ca2+/mg mitochondrial protein]), releasing all the calcium and causing a plateau in the arsenazo fluorescence.
(A–C) Representative CRC traces from E16.5 WT +/−1 μM CsA (A), E16.5 CypD KO +/−1 μM CsA (B), and Adult WT and CypD KO (C) heart mitochondria. Calcium pulses were 10 μM in E16.5 and 20 μM in Adult experiments.
(D) CRC of WT mitochondria from E16.5, P1, P7, weanling (W) and adult (A) hearts, +/− 1 μM CsA.
(E and F) CRC levels in mitochondria from WT and CypD KO E16.5 (E) and adult (F) hearts +/− treatment with 1 μM CsA. Data in D-F is presented as Mean ± SEM and analyzed by one-way ANOVA with Tukey’s or Sidak’s multiple comparison test. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗∗p < 0.0001. N: 3–5 samples per condition.