Regional differences in the activation of synaptosomal mitochondrial Ca2+ uptake by spermine in rat brain.
Several properties of Ca2+ uptake by isolated synaptosomal mitochondria were characterized by using a repetitive Ca2+ loading technique. Synaptosomal mitochondria maintained extramitochondrial Ca2+ concentration at submicromolar levels when challenged with successive additions of small amounts of Ca2+. Ca2+ uptake under these conditions was markedly stimulated by the presence of spermine, a polyamine found in high concentrations in brain. Moreover, mitochondria isolated from telencephalic areas of rat brain were activated to a greater extent by spermine than were mitochondria from non-telencephalic brain regions. The present results support the idea that brain mitochondria could play a significant role in limiting the intraneuronal rise in Ca2+ that follows stimulation or injury. In addition, telencephalic mitochondria exhibit more flexibility in the regulation of Ca2+ uptake than do mitochondria from phylogenetically older non-telencephalic brain regions and this could be related to differences in Ca2+ influx mechanisms in these brain regions.
Center for the Neurobiology of Learning and Memory, University of California, Irvine 92717.
J
J
Jensen
G
G
Lynch
M
M
Baudry
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009928:Organ Specificity; D051381:Rats; D011919:Rats, Inbred Strains; D013096:Spermine / Q000494:pharmacology*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D013687:Telencephalon / Q000378:metabolism
D013096:Spermine; D002118:Calcium