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Na + /H + exchange in mitochondria as monitored by BCECF fluorescence
Author(s) -
Kapus András,
Ligeti Erzsébet,
Fonyó Attila
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81426-7
Subject(s) - chemistry , kinetics , matrix (chemical analysis) , fluorescence , mitochondrial matrix , biophysics , mitochondrion , analytical chemistry (journal) , ion exchange , membrane potential , chromatography , cytosol , biochemistry , ion , biology , enzyme , physics , organic chemistry , quantum mechanics
The recently developed method of loading isolated heart mitochondria with the fluorescent pH indicator, BCECF, was applied to monitor the Na + 0 /H + i exchange process from the matrix side of the membrane. The Na + ‐induced changes in the pH of the matrix (pH m ) showed that: (i) the Na + 0 /H + i exchange followed Michaelis‐Menten kinetics with respect to external Na + with a K m of approx. 20 mM; (ii) in contrast to this, the dependence of the exchange rate on the matrix [H + ] did not obey the Michaelian model. No Na + ‐induced alkalinization occurred above a pH m of 7.45±0.09 ( n =4). Below this value the reciprocal of the transport rate and that of the matrix [H + ] deviated upwardly from the straight line. The results suggest that internal H + might exert allosteric control on the mitochondrial Na + /H + exchange process.