1 Mariannick Marcil, Karine Bourduas, Alexis Ascah, Yan Burelle ...

Calcium concentration in the matrix is the most important determinant of PTP gating, with
high [Ca 2+ ] favouring the open conformation (60). In addition, a variety of factors modulate the
sensitivity of the PTP to Ca 2+ , including variations in the , redox state of pyridine nucleotides
(PNs), ROS production and matrix pH as well as Pi and adenylates content (see (60) for review).
In skeletal muscle mitochondria the Ca 2+ sensitivity of the PTP was also shown to depend on the
type of respiratory substrate oxidized, with complex I donors acting as sensitizers compared to
complex II donors (22).
In the present study we therefore determined if exercise training is associated with
changes in the sensitivity to Ca 2+ -induced PTP opening in isolated heart mitochondria. We also
determined if the type of substrate used for energization influences Ca 2+ -induced PTP opening in
this organ and whether exercise training elicits changes in selected physiological modulators of
PTP gating.
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