After an elegant study in highly purified inside-out submitochondrial particles, which indicated a Pi-dependent Ca2+ uptake, the view has emerged that Pi may play a key role in the physiological pathway of mitochondrial Ca2+ efflux. This paper reports a novel observation, namely the stimulation by Pi of an energydependent Ca2+ efflux which leads to a shift of the steady state extramitochondrial free Ca2+ towards lower pCao values. The distribution of Ca2+ is correlated with the value of deltapsi indicating that deltapsi modulates the activity of the efflux pathway. Thus an increase of deltapsi above 130 mV leads to increased activity of the efflux pathway, with correspondent increase of extramitochondrial free Ca2+ at steady state. Ca2+ distribution at high deltapsi appears therefore to reflect a kinetic steady state were uptake via the electrical uniport is counterbalanced by efflux via the Pi-stimulated, Mg2+dependent pathway modulated by deltapsi.

A Membrane Potential Modulated Pathway for Ca2+ Efflux in Rat Liver Mitochondria

BERNARDI, PAOLO;
1982

Abstract

After an elegant study in highly purified inside-out submitochondrial particles, which indicated a Pi-dependent Ca2+ uptake, the view has emerged that Pi may play a key role in the physiological pathway of mitochondrial Ca2+ efflux. This paper reports a novel observation, namely the stimulation by Pi of an energydependent Ca2+ efflux which leads to a shift of the steady state extramitochondrial free Ca2+ towards lower pCao values. The distribution of Ca2+ is correlated with the value of deltapsi indicating that deltapsi modulates the activity of the efflux pathway. Thus an increase of deltapsi above 130 mV leads to increased activity of the efflux pathway, with correspondent increase of extramitochondrial free Ca2+ at steady state. Ca2+ distribution at high deltapsi appears therefore to reflect a kinetic steady state were uptake via the electrical uniport is counterbalanced by efflux via the Pi-stimulated, Mg2+dependent pathway modulated by deltapsi.
1982
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/141897
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