CD2-LIVER MITOCHONDRIA WERE MODIFIED BY MONOVALENT CATIONS( EFFECTS ON RESPIRATION AND SWELLING OF RAT)

Changes in Cd2+ effects on respiration of succinate-energized rat live r mitochondria were studied after replacement of 100 mM KCl in an incu bation medium by equimolar amounts of NaCl or LiCl, or by 200 mM sucro se. In KCl medium, 2.5-10 mu M Cd2+ decreased the state 3 and 2,4-dini trophenol (DNP)-stimulated respiration of mitochondria, and increased their respiration in the state 4, however, 10-40 mu M Cd2+ diminished the state 4 respiration. Compared to the experiments with KCl medium, it was demonstrated that Cd2+ effects on the mitochondrial respiration was increased in NaCl medium, decreased in sucrose medium, and unchan ged in LiCl medium, except that 10-25 mu M Cd2+ decreased the state 4 respiration of mitochondria in the same way as in the NaCl medium. Cd2 + (20 mu M) stimulated an extensive swelling of nonenergized mitochond ria incubated in 125 mM nitrate media, the effect being increased in t he series of Li < Na < K < NH4. Swelling of succinate-energized mitoch ondria incubated in K-acetate medium was additionally stimulated by 10 mu M C-d2+. The initially low swelling of succinate-energized mitocho ndria in the KCl medium increased with increase in Cd2+ concentrations in this medium. Differences found in the Cd2+ effects on respiration and on swelling of mitochondria incubated in the media used are discus sed in terms of general ion permeabilities and differences in Cd2+ bin ding, its uptake, and interaction with respiratory enzymes. (C) 1998 E lsevier Science Inc. All rights reserved.