Strontium excitability of the inner mitochondrial membrane: regenerative strontium-induced strontium release.
Regenerative Sr(++)-induced Sr++ release from isolated rat liver mitochondria was studied using ion-selective electrode techniques. Mitochondria, when exposed to a pulse of Sr++, demonstrated a reversible and transient increase in inner membrane permeability to K+ and H+ ions. The increase in permeability was an all-or-none process with a threshold dependent on the amplitude of the Sr++ pulse. The threshold concentration of Sr++ was lowered from 120-150 microM to 20-30 microM when mitochondria were preloaded with 100 nmoles Sr++/mg protein. Release of matrix-stored divalent cations provided a mechanism for amplification of the extramitochondrial Sr++ concentration (regenerative Sr(++)-induced Sr++ release). The mitochondrial inner membrane became refractory, since subsequent cycles of excitation could not be immediately induced. These experiments demonstrate that the inner mitochondrial membrane is an excitable membrane, with threshold-dependent, regenerative and subsequently refractile Sr(++)-induced Sr++ release characteristics.
Holmuhamedov
E L
EL
Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region.
Teplova
V V
VV
Chukhlova
E A
EA
Evtodienko
Y V
YV
Ulrich
R G
RG
D000818:Animals; D002118:Calcium / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism*; D017736:Ion-Selective Electrodes; D008930:Mitochondria, Liver / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D010539:Permeability; D011188:Potassium / Q000378:metabolism; D011522:Protons; D051381:Rats; D017208:Rats, Wistar; D013324:Strontium / Q000378:metabolism* / Q000494:pharmacology
D011522:Protons; D011188:Potassium; D010100:Oxygen; D002118:Calcium; D013324:Strontium