Calcium mobilization from the intracellular mitochondrial and nonmitochondrial stores of the rat cerebellum.
Two major intracellular Ca2+ stores, the mitochondrial and nonmitochondrial (microsomes) fractions isolated from rat cerebellum exhibited a Ca2+ concentration and ATP-dependent Ca2+ accumulation. The maximal Ca2+ accumulation in mitochondria was higher than in microsomes, but the affinity of the mitochondria for Ca2+ was lower. In this study, Ca2+ accumulation within the mitochondria was energized by ATP hydrolysis. Thus, the protonophore, carbonyl cyanide p-trifluoromethoxyphenylhydrazone, and the F1F0 ATP synthase inhibitor, oligomycin, blocked Ca2+ accumulation and induced the discharge of the entrapped Ca2+ in the mitochondria, whereas the metabolic inhibitor, rotenone, affected neither the Ca2+ accumulation nor discharge. On the other hand, the uniporter inhibitor, ruthenium red, blocked the mitochondrial accumulation of Ca2+, but did not cause the discharge of preloaded Ca2+. In addition, arachidonic acid (AA), sphingosylphosphorylcholine (SPC) and sphingosine (SPH) elicited the dose-dependent release of Ca2+ from microsomal stores. Although the magnitudes of the Ca2+ release induced by AA, SPC or SPH were all dependent on the presence of extravesicular Ca2+ at concentrations ranging from 0.01 to 0.1 microM Ca2+, only the AA- and SPC-evoked Ca2+ releases were insensitive to temperature. The mitochondria were more sensitive than the microsomes to the AA induced release of accumulated Ca2+. Our results indicate the existence of multiple intracellular Ca2+ stores in nerve cells which can be released by various Ca2+ mediators.
Huang
W C
WC
Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan.
Chueh
S H
SH
D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D066298:In Vitro Techniques; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012430:Ruthenium Red / Q000494:pharmacology; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D001095:Arachidonic Acids; D002121:Calcium Channel Blockers; C005356:sphingosine phosphorylcholine; D010767:Phosphorylcholine; D012430:Ruthenium Red; D013110:Sphingosine; D002118:Calcium