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Uncoupler-stimulated Na+ pump and its possible role in the halotolerant bacterium, Ba.

Uncoupler-stimulated Na+ pump and its possible role in the halotolerant bacterium, Ba.

Authors :
Ken-Dror S
Shnaiderman R
Avi-Dor Y
Source :
Archives of biochemistry and biophysics [Arch Biochem Biophys] 1984 Mar; Vol. 229 (2), pp. 640-9.
Publication Year :
1984

Abstract

In cells of Ba1 suspended in K salt as the osmoticum, the respiratory rate declined by 80% between the pH values of 6.5 and 8.5. Catalytic amounts of Na+ ions prevented this drop. The possibility that Na+ exerted its effect by an influence on proton fluxes across the membrane (Na+/H+ exchange) was explored. Addition of catalytic amounts of Na+ ions to cells respiring at pH 8.5 elicited an influx of protons and, as a result, the delta pH across the membrane became diminished. delta psi (membrane potential) was not affected by Na+. At pH 6.5, Na+ caused no proton influx. FCCP (carbonylcyanide-p-trifluoromethoxyphenylhydrazone) collapsed delta psi, but the Na+-dependent proton influx observed at pH 8.5 became enhanced, leading to an inversion of delta pH (more acid inside). When a Na salt was used as the osmoticum, delta pH of reversed polarity was generated by respiration also in the absence of FCCP. Respiring, inverted membrane vesicles responded to a Na+ pulse essentially as the intact cells. Based on the above and some additional findings it is suggested that these Na+-dependent effects are suited to prevent a raise in the intracellular pH over the level which hinders the respiratory activity. It may also play a role in the regulation of intracellular Na salt content.

Details

Language :
English
ISSN :
0003-9861
Volume :
229
Issue :
2
Database :
MEDLINE
Journal :
Archives of biochemistry and biophysics
Publication Type :
Academic Journal
Accession number :
6322699
Full Text :
https://doi.org/10.1016/0003-9861(84)90197-8