Superstoichiometric Ca2+ uptake supported by hydrolysis of endogenous ATP in rat liver mitochondria.
The nature of the energy store causing rapid superstoichiometric leads to H+/2e minus ejection and leads to Ca2+/2e minus uptake ratios in rat liver mitochondria pulsed with Ca2+ has been investigated. The extent and the rate of the initial fast superstoichiometric phase of H plus ejection were greatly reduced by oligomycin and other ATPase inhibitors; the subsequent shoichiometric phase was unaffected. No such inhibition was seen with atractyloside. Similarly, the initial fast phase of Ca2+ uptake was reduced in extent by oligomycin, whereas the slower stoichiometric phase was unaffected. Moreover, the ATP content of mitochondria previously incubated with succinate decreased by about 80% within 5 s after pulsing with Ca2+. The energy store for superstoichiometric Ca2+ uptake and H plus injection is thus identified as endogenous ATP.
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D007700:Kinetics; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D009840:Oligomycins / Q000494:pharmacology; D051381:Rats
D009840:Oligomycins; D000255:Adenosine Triphosphate; D002118:Calcium