Complex sentence: There is controversy about the question of whether the MPTP is able to exist in a harmless, "low-conductance" state which would not induce MPT and which would allow certain molecules and ions to cross the mitochondrial membranes.
Split into simpler sentences: There is controversy about the question of whether the MPTP is able to exist in a harmless, "low-conductance" state. This low-conductance state would not induce MPT and would allow certain molecules and ions to cross the mitochondrial membranes.