The Na(+)-independent Ca2+ efflux mechanism of liver mitochondria is not a passive Ca2+/2H+ exchanger.
Whether the Na(2+)-independent Ca2+ efflux mechanism of liver mitochondria is a Ca2+/2H+ exchanger and whether this exchanger is a passive mechanism have been controversial since shortly after the discovery of this mechanism. Here, a new approach to determining if the mechanism is passive is developed based on the energy available to a passive Ca2+/2H+ exchanger. Conditions are identified in which the Na(+)-independent Ca2+ efflux mechanism transports Ca2+ out of mitochondria against a Ca2+ gradient many times greater than that possible for a passive Ca2+/2H+ exchanger, thus ruling this out as a possible mechanism.
Department of Biophysics, School of Medicine and Dentistry, University of Rochester, New York 14642.
K K
KK
Gunter
M J
MJ
Zuscik
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TE
Gunter
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002151:Calorimetry; D002352:Carrier Proteins / Q000378:metabolism; D007700:Kinetics; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D008954:Models, Biological; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000494:pharmacology*
D002352:Carrier Proteins; D012964:Sodium; D002118:Calcium