The Na(+)-independent Ca2+ efflux mechanism of liver mitochondria is not a passive Ca2+/2H+ exchanger |
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| Authors: | K K Gunter M J Zuscik T E Gunter |
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| Institution: | Department of Biophysics, School of Medicine and Dentistry, University of Rochester, New York 14642. |
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| Abstract: | 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. |
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