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It has been reported (Becker, G.L., Fiskum, G. and Lehninger, A.L. (1980) J. Biol. Chem. 255, 9009-9012) that respiring rat liver mitochondria suspended in KC1 medium containing ATP, Mg2+ and phosphate, maintain a steady state extramitochondrial free Ca2+ concentration of about 0.5 microM. The results reported here show that the addition of the antibiotic X-537A, at concentrations far below those required for ionophorous activity, caused a perturbation in this steady state, lowering the extramitochondrial free Ca2+ concentration by about 0.20 microM. This shift in steady state was clarified by a study of X-537A inhibition of the Ca2+ efflux induced by ruthenium red; a half-maximum effect was observed at approximately 25 nM X-537A. No effect on Ca2+ transport through the influx uniporter was observed. The possibility of a generalized stabilizing action of the antibiotic on the mitochondrial membrane seems to be ruled out by its effectiveness at very low concentrations.
L Pereira da Silva, and
C F Bernardes, and
A E Vercesi
April 1984,
Biochemistry,
L Pereira da Silva, and
C F Bernardes, and
A E Vercesi
March 1984,
Bioscience reports,
L Pereira da Silva, and
C F Bernardes, and
A E Vercesi
November 1980,
FEBS letters,
L Pereira da Silva, and
C F Bernardes, and
A E Vercesi
October 1980,
FEBS letters,
L Pereira da Silva, and
C F Bernardes, and
A E Vercesi
January 1985,
The Biochemical journal,
L Pereira da Silva, and
C F Bernardes, and
A E Vercesi
February 1991,
Biochimica et biophysica acta,
L Pereira da Silva, and
C F Bernardes, and
A E Vercesi
February 1979,
Nature,
L Pereira da Silva, and
C F Bernardes, and
A E Vercesi
January 1985,
The Journal of biological chemistry,
L Pereira da Silva, and
C F Bernardes, and
A E Vercesi
April 1984,
Biochemistry international,
L Pereira da Silva, and
C F Bernardes, and
A E Vercesi
November 1985,
Archives of biochemistry and biophysics,
