The Journal of Neuroscience, March 15, 2001, 21(6):1893-1901
Mitochondria Control AMPA/Kainate Receptor-Induced Cytoplasmic
Calcium Deregulation in Rat Cerebellar Granule Cells
A. Cristina
Rego,
Manus W.
Ward, and
David G.
Nicholls
Buck Institute for Age Research, Novato, California 94945-1400
Although mitochondria mediate the delayed failure of cytoplasmic
Ca2+ homeostasis [delayed Ca2+
deregulation (DCD)] in rat cerebellar granule cells resulting from
chronic activation of NMDA receptors, their role in AMPA/KA-induced DCD
remains to be established. The mitochondrial ATP synthase inhibitor
oligomycin protected cells against KA- but not NMDA-evoked DCD. In
contrast to NMDA-evoked DCD, no additional protection was afforded by
the further addition of rotenone. The effects of KA on cytoplasmic
Ca2+ homeostasis, including the protection afforded
by oligomycin, could be reproduced by veratridine. KA exposure induced
a partial mitochondrial depolarization that was enhanced by oligomycin, indicating ATP synthase reversal. The nonglycolytic substrates pyruvate
and lactate were unable to maintain Ca2+ homeostasis
in the presence of KA. In contrast to NMDA, KA exposure did not cause
mitochondrial Ca2+ loading. The data indicate
that Na+ entry via noninactivating AMPA/KA receptors
or voltage-activated Na+ channels compromises
mitochondrial function sufficiently to cause ATP synthase reversal.
Oligomycin may protect by preventing the consequent mitochondrial drain
of cytoplasmic ATP.
Key words:
calcium; cerebellar granule cells; kainate; mitochondrial
membrane potential; NMDA; glutamate excitotoxicity; glutamate
receptors
Copyright © 2001 Society for Neuroscience 0270-6474/01/2161893-09$05.00/0