ATP hydrolysis induces variable porosity to mannitol in the mitochondrial inner membrane.
Osmotic titration of ATPase activity in rat liver mitochondria was consistent with enhanced porosity of the mitochondrial inner membrane to mannitol due to ATP hydrolysis even when endogenous respiration was inhibited by rotenone. The occluded ATPase activity, which exhibits osmotic activation with an optimum near isotonicity, depends both on the ATPase activity per se and on the activity of the ADP/ATP carrier. Purified ADP/ATP carrier incorporated into small, unilamellar liposomes was critically shown to exhibit dependence of its activity on the osmotic pressure differences across the membrane, with maximal activity corresponding to isotonicity, regardless of the actual internal tonicity.
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D007425:Intracellular Membranes / Q000378:metabolism*; D008081:Liposomes; D008353:Mannitol / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D000226:Mitochondrial ADP, ATP Translocases / Q000378:metabolism*; D009713:Nucleotidyltransferases / Q000378:metabolism*; D009997:Osmotic Pressure; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D006180:Proton-Translocating ATPases / Q000378:metabolism; D051381:Rats; D012402:Rotenone / Q000494:pharmacology; D013395:Sucrose / Q000378:metabolism
D008081:Liposomes; D012402:Rotenone; D008353:Mannitol; D013395:Sucrose; D011189:Potassium Chloride; D000255:Adenosine Triphosphate; D000226:Mitochondrial ADP, ATP Translocases; D009713:Nucleotidyltransferases; D006180:Proton-Translocating ATPases