Na+/H+ exchange in mitochondria as monitored by BCECF fluorescence

FEBS Letters

Ligeti, Erzsébet¹  Fonyó, Attila¹  Kapus, András¹ 

[1] Department of Physiology, Semmelweis University of Medicine, PO Box 259, H-1444 Budapest 8, Hungary

关键词: Na+/H+ exchange;    Matrix pH;    Biscarboxyethylcarboxyfluorescein;    (Mitochondria);    BCECF/AM;    the acetoxymethylester form of 2′;    7′-bis(carboxyethyl)-5(6)-carboxyfluorescein;    CCCP;    carbonyl cyanide p-trifluoromethoxyphenylhydrazone;    pHm;    pH of the intramitochondrial matrix;    Δψ;    mitochondrial membrane potential;    TMPD;    N;    N;    N′;    N′-tetramethyl-p -phenylenediaminedehydrochloride;    TPP+;    tetraphenylphosphonium;   

DOI  :  10.1016/0014-5793(89)81426-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown