[Mg2+ release from heart mitochondria in ischemia: is it the defense mechanism or damage?].

It is established that at the early stage of total heart ischemia in rats (5-10 min) the oligomycin-sensitive ATPase activity of mitochondria measured in heart homogenates in the medium and containing no Mg2+ decreases considerably, whereas the activity of respiratory chain, the value of respiratory control and Mg2+-ATPase activity are practically unchanged. The hypothetic trigger mechanism is suggested for Mg2+ ejection from mitochondria under conditions of respiration cessation. It is supposed to be a defence reaction of cells aimed to prevent ATP hydrolysis by mitochondria under ischemia.