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Vasington 1962 J Biol Chem

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Vasington FD, Murphy JV (1962) Ca++ uptake by rat kidney mitochondria and its dependence on respiration and phosphorylation. J Biol Chem 237:2670-7.

Β» PMID: 13925019 Open Access; PDF

Vasington FD, Murphy JV (1962) J Biol Chem

Abstract: Rat kidney mitochondria bind large quantities of Ca++. Maximal Ca++ binding requires the presence o f a respiratory substrate such as isocitrate or succinate, as well as adenosine triphosphate (ATP), inorganic orthophosphate (Pi), and Mg++. No Ca++ is bound in the absence of ATP, whereas if Pi or Mg++ is omitted, the amount of Ca++ bound is decreased 40 to 70%. Adenosine diphosphate (ADP) can substitute partially for ATP, presumably through formation of ATP by adenylate kinase, but other nucleoside di- and triphosphates tested are essentially inactive.

Respiratory inhibitors such as Amytal, antimycin A, cyanide, and azide inhibit Ca++ binding, as do uncoupling agents such as dinitrophenol, dicoumarol, and gramicidin. Significantly, Ca++ is bound by mitochondria even in the presence of uncoupling quantities of Ca++. Dinitrophenol and other uncoupling agents therefore block Ca++ binding under conditions in which phosphorylation is already uncoupled by Ca++.

Endogenous Ca++ is released from mitochondria incubated in the absence of ATP or ADP or in the presence of antimycin A, dinitrophenol, or HgC12, suggesting that similar factors influence the retention of endogenous Ca++ and the uptake of exogenous Ca++. Ca++ binding is stimulated by 0.05 to 0.15 M Na+ or K+ and 0.05 to 0.25 M Li+, whereas NH4+, Rb+, and Cs+ have little effect or are inhibitory at these concentrations; at higher concentrations, all of the alkali metal cations become inhibitory. β€’ Keywords: Ca++ uptake, Respiration, Phosphorylation


Labels: MiParea: Respiration 


Organism: Rat  Tissue;cell: Kidney  Preparation: Isolated mitochondria 

Regulation: ADP, Calcium, Coupling efficiency;uncoupling, Inhibitor, Ion;substrate transport 



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