Evidence for the presence of a reversible Ca2+-dependent pore activated by oxidative stress in heart mitochondria

Abstract

Rat heart mitochondria became permeabilized to sucrose when incubated with 100 nmol of Ca2"/mg of protein in the presence of P. Ca2" chelation with EGTA restored impermeability to sucrose, which became entrapped in the matrix space. t-Butylhydroperoxide markedly promoted permeabilization in the presence of Ca2" but not in its absence, and Ca2+-plus-t-butylhydroperoxide-induced permeabilization was reversed by EGTA. The data suggest that Ca2" and oxidative stress synergistically promote the reversible opening of an inner membrane pore.