CORRELATION BETWEEN DEGREE OF RUPTURE OF OUTER MITOCHONDRIAL-MEMBRANEAND CHANGES OF KINETICS OF REGULATION OF RESPIRATION BY ADP IN PERMEABILIZED HEART AND LIVER-CELLS

Kinetics of regulation of respiration by ADP in skinned cardiac fibers and permeabilized isolated hepatocytes was compared before and after mitochondrial swelling due to hypoosmotic treatment in 30-50 mOsM solu tions. In both systems the apparent Km for ADP was high before mitocho ndrial swelling and equal to 297 +/- 35 mu M and 275 +/- 35 mu M, corr espondingly. Hypoosmotic treatment resulted in the rupture of outer mi tochondrial membrane and in the loss of exogenous cytochrome c, and bo th in skinned cardiac fibers and permeabilized hepatocytes the value o f apparent Km for ADP was decreased in correlation with the extent of the rupture of the outer mitochondrial membrane. It is concluded that both in heart and liver cells in vivo, the ADP diffusion in the cells is retarded due to very low permeability of the outer mitochondrial me mbrane for ADP. (C) 1995 Academic Press, Inc.