High Quality Content by WIKIPEDIA articles! The Mitochondrial Permeability Transition, or MPT, is defined as an increase in the permeability of the mitochondrial membranes to molecules of less than 1500 Daltons in molecular weight. MPT results from the opening of a mitochondrial permeability transition pore, also known as the MPT pore or MPTP. The MPT pore is a protein pore that is formed in the inner membrane of the mitochondria under certain pathological conditions such as traumatic brain injury and stroke. Induction of the permeability transition pore can lead to mitochondrial swelling and cell death through apoptosis or necrosis depending on the particular biological setting.