'Pore' formation is not required for the hydroperoxide-induced Ca2+ release from rat liver mitochondria.
It has recently been suggested by several investigators that the hydroperoxide- and phosphate-induced Ca2+ release from mitochondria occurs through a non-specific 'pore' formed in the mitochondrial inner membrane. The aim of the present study was to investigate whether 'pore' formation actually is required for Ca2+ release. We find that the t-butyl hydroperoxide (tbh)-induced release is not accompanied by stimulation of sucrose entry into, K+ release from, and swelling of mitochondria provided re-uptake of the released Ca2+ ('Ca2+ cycling') is prevented. We conclude that (i) the tbh-induced Ca2+ release from rat liver mitochondria does not require 'pore' formation in the mitochondrial inner membrane, (ii) this release occurs via a specific pathway from intact mitochondria, and (iii) a non-specific permeability transition ('pore' formation) is likely to be secondary to Ca2+ cycling by mitochondria.
Schlegel
J
J
Laboratory of Biochemistry I, Swiss Federal Institute of Technology (ETH), Zürich.
Schweizer
M
M
Richter
C
C
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent; D005260:Female; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000648:ultrastructure; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D008933:Mitochondrial Swelling; D010710:Phosphates / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012430:Ruthenium Red
D002413:Cations, Divalent; D010710:Phosphates; D012430:Ruthenium Red; D006861:Hydrogen Peroxide; D011188:Potassium; D002118:Calcium