Open AccessIon Transport in Liver Mitochondria
Author(s) -
Rossi E.,
Azzone G. F.
Publication year - 1969
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1969.tb19626.x
Subject(s) - valinomycin , osmotic concentration , membrane potential , chemistry , ion transporter , biophysics , respiration , mitochondrion , oxygen , ion , efflux , membrane transport , analytical chemistry (journal) , membrane , biochemistry , chromatography , biology , anatomy , organic chemistry
1 The relationship between translocation of K + and respiration has been studied under conditions where large variations of the transmembrane K + concentration gradient were obtained. It is found that the energy expenditure is a function of the number of ions translocated and not of the transmembrane concentration gradient. The K + /∼ ratio is slightly below 3 when measured on the total oxygen uptake and between 3 and 4 when measured on the Δ oxygen uptake. 2 The maximal [K + ] i /[K + ] o ratio maintained by respiring liver mitochondria is about 1,600 corresponding to an equilibrium potential of 192 mV. When the [K + ] i /[K + ] o ratio exceeds 2,000 times addition of valinomycin under aerobic conditions causes an efflux instead of an uptake of K + . 3 Mitochondria behave as perfect osmometers in a wide range of osmolarities. It can be calculated that the concentration of osmotically active internal K + corresponds to 45% of the total osmolarity of the medium.