Mitochondrial deenergization underlies neuronal calcium overload following a prolonged glutamate challenge.
The purpose of our work was to study the relationship between glutamate (GLU)-induced mitochondrial depolarization and deterioration of neuronal Ca2+ homeostasis following a prolonged GLU challenge. The experiments were performed on cultured rat cerebellar granule cells using the fluorescent probes, rhodamine 123 and fura-2. All the cells, in which 100 microM GLU (10 microM glycine, 0 Mg2+) induced only relatively slight mitochondrial depolarization (1.1-1.3-fold increase in rhodamine 123 fluorescence), retained their ability to recover [Ca2+]i following a prolonged GLU challenge. In contrast, the cells in which GLU treatment induced pronounced mitochondrial depolarization (2-4-fold increase in rhodamine 123 fluorescence), exhibited a high Ca2+ plateau in the post-glutamate period. Application of 3-5 mM NaCN or 0.25-1 microM FCCP during this Ca2+ plateau phase usually failed to produce a further noticeable increase in [Ca2+]i. Regression analysis revealed a good correlation (r2 = 0.88 +/- 0.03, n = 19) between the increase in the percentage of rhodamine 123 fluorescence and the post-glutamate [Ca2+]i. Collectively, the results obtained led us to conclude that the GLU-induced neuronal Ca2+ overload was due to the collapse of the mitochondrial potential and subsequent ATP depletion.
Khodorov
B
B
Institute of General Pathology and Pathophysiology, Moscow, Russian Federation. rans@rans.msk.ru
Pinelis
V
V
Vergun
O
O
Storozhevykh
T
T
Vinskaya
N
N
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D000968:Antimycin A / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D016257:Fura-2; D018698:Glutamic Acid / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009840:Oligomycins / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D020112:Rhodamine 123; D012235:Rhodamines; D012966:Sodium Cyanide / Q000494:pharmacology
D009840:Oligomycins; D012235:Rhodamines; C032456:antimycin; D020112:Rhodamine 123; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D018698:Glutamic Acid; D000968:Antimycin A; D000255:Adenosine Triphosphate; D012966:Sodium Cyanide; D002118:Calcium; D016257:Fura-2