ATP-induced unspecific channel in yeast mitochondria.
ATP induced swelling of isolated yeast mitochondria suspended in an isoosmotic solution of potassium gluconate. Valinomycin stimulated the swelling rate, indicating that K+ influx in the presence of ATP is rate-controlling. This swelling was inhibited by ADP, phosphate (probably acting on the external face of the inner membrane), and Mg2+, which forms a complex with ATP. ATP-induced swelling did not require working F0-F1-ATPase since it was not inhibited by oligomycin and uncoupler. CTP and GTP also induced a swelling. ATP also induced mitochondrial swelling in potassium glutamate, chloride, and acetate but not in phosphate solutions. Sodium, but not ammonium, can replace potassium ion. It is probable that the ATP-channel opening also necessitates an electrogenic cation influx. Respiration also induced swelling of mitochondria suspended in isoosmotic potassium gluconate solution. ATP- or respiration-induced swelling were inhibited equally by N,N'-dicyclohexylcarbodiimide, propranolol, and Zn2+ but not by quinine; all these drugs inhibit the H+/K+ exchange. It was concluded that this unspecific channel is not open under conditions used to measure oxidative phosphorylation. Its physiological role remains unknown.
Guérin
B
B
Institut de Biochimie et Génétique Cellulaires, Université de Bordeaux 2, France.
Bunoust
O
O
Rouqueys
V
V
Rigoulet
M
M
D000085:Acetates / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D001692:Biological Transport; D004305:Dose-Response Relationship, Drug; D005942:Gluconates / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010316:Particle Size; D010710:Phosphates / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011803:Quinine / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
D000085:Acetates; D005942:Gluconates; D007473:Ion Channels; D010710:Phosphates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011803:Quinine; D008274:Magnesium; D011188:Potassium