Flow cytometric study of mitochondrial dysfunction after AMPA receptor activation.
The effect of AMPA-receptor stimulation on MMP and on the concentration of intracellular calcium ([Ca2+]i) was studied in dissociated CGC from rat pups, by flow cytometry. In the presence of cyclothiazide, AMPA induced a sodium-independent decrease in MMP up to 30.7+/-2.5%. This effect was antagonized by CNQX and NBQX. Mepacrine and dibucaine reversed the effect of AMPA on MMP, suggesting that it is mediated by a release of arachidonic acid. AMPA alone induced a slight (about 7%) increase in [Ca2+]i. In the presence of cyclothiazide, AMPA induced a concentration-dependent [Ca2+]i increase up to 29.10+/-2.10% that was not reversed by flunarizine. This increase was similar to that observed in a Na+-free medium, and was antagonized by CNQX and NBQX, but not by MK-801. Mitochondria play a key role in the modulation of [Ca2+]i since a significant [Ca2+]i increase was found in the presence of FCCP. On the other hand, the dantrolene-sensitive calcium pools do not participate in the [Ca2+]i increase induced by stimulation of AMPA receptors. It is concluded that when AMPA-receptor desensitization is blocked, a decrease in MMP and an increase in [Ca2+]i occurs, which could be additional events to potentiate neuronal cell death induced by glutamate.
Department of Pharmacy, University of Barcelona, Spain.
A
A
Camins
C
C
Gabriel
L
L
Aguirre
F X
FX
Sureda
M
M
Pallàs
E
E
Escubedo
J
J
Camarasa
D000818:Animals; D002118:Calcium / Q000378:metabolism; D005434:Flow Cytometry; D007425:Intracellular Membranes / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D008928:Mitochondria / Q000502:physiology*; D009994:Osmolar Concentration; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000502:physiology*
D018091:Receptors, AMPA; D002118:Calcium