Figure 3. Effect of acute exercise on mitochondrial resistance to Ca²⁺-induced MPT (mitochondrial permeability transition) pore opening.

Pore opening was induced by subsequent additions of Ca²⁺ pulses to isolated muscle mitochondria. A, original recordings of absorbance measured at 540 nm. Arrows denote additions of Ca²⁺ (2 μmol (U CS)⁻¹). B, mitochondrial Ca²⁺ resistance denotes the accumulated amount of Ca²⁺ required to initiate rapid progressive swelling of mitochondria indicating opening of MPT pores. Subjects cycled at 70% of V̇_O2peak for 75 min. Values are mean ± s.e.m., n= 7, *P < 0.05.