Quantitative and mechanistic aspects of the hydroperoxide-induced release of Ca2+ from rat liver mitochondria

Eur J Biochem. 1985 Jun 18;149(3):633-9. doi: 10.1111/j.1432-1033.1985.tb08971.x.

Abstract

We have previously demonstrated in rat liver mitochondria a hydroperoxide-induced hydrolysis of pyridine nucleotides and release of Ca2+ [Lötscher, H. R., Winterhalter, K. H., Carafoli, E. & Richter, C. (1979) Proc. Natl Acad. Sci. USA 76, 4340-4344, and Lötscher, H. R., Winterhalter, K. H., Carafoli, E. & Richter, C. (1980) J. Biol. Chem. 255, 9325-9330]. Here we investigate pyridine nucleotide hydrolysis and Ca2+ release under conditions of minimized Ca2+ cycling and with smaller Ca2+ loads. The extent of pyridine nucleotide hydrolysis, measured by pyridine-nucleotide-derived nicotinamide release from intact mitochondria, and the Ca2+ release rate show a very similar sigmoidal dependence on the mitochondrial Ca2+ load. The hydrolysis of oxidized pyridine nucleotides is limited under non-cycling conditions. Whereas pyridine nucleotide hydrolysis as measured by nicotinamide release is extensive, net loss of mitochondrial pyridine nucleotides is observed only at relatively high Ca2+ loads. Our results indicate the ability of mitochondria to resynthesize pyridine nucleotides after hydrolysis. Neither a decrease of reduced, nor an increase of oxidized, mitochondrial glutathione favour Ca2+ release. From these and previous findings it is concluded that the hydroperoxide-induced Ca2+ release is triggered by a factor which is distal to the oxidation of mitochondrial pyridine nucleotides. Ca2+ release is stimulated when the movement of protons across the inner mitochondrial membrane is facilitated, giving evidence for the operation of the hydroperoxide-induced release pathway as a Ca2+/H+ antiport.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport
  • Calcium / metabolism*
  • Female
  • Glutathione / metabolism
  • Glutathione Reductase / metabolism
  • Hydrolysis
  • In Vitro Techniques
  • Mitochondria, Liver / enzymology
  • Mitochondria, Liver / metabolism*
  • NAD / metabolism
  • NADP / metabolism
  • Niacinamide / metabolism
  • Oxidation-Reduction
  • Peroxides / metabolism*
  • Protons
  • Rats
  • Rats, Inbred Strains

Substances

  • Peroxides
  • Protons
  • NAD
  • Niacinamide
  • NADP
  • Glutathione Reductase
  • Glutathione
  • Calcium