Background and Purpose - Experimental evidence supports a major role of increased intracellular calcium [Ca2+](i) levels in the induction of neuronal damage during cerebral ischemia. However, the source of Ca2+ rise has not been fully elucidated. To clarify further the role and the origin of Ca2+ in cerebral ischemia, we have studied the effects of various pharmacological agents in an in vitro model of oxygen (O2)/glucose deprivation. Methods - Pyramidal cortical neurons were intracellularly recorded from a slice preparation. Electrophysiological recordings and microfluorometric measurements of [Ca2+](i) were performed simultaneously in slices perfused with a glucose-free physiological medium equilibrated with a 95% N2/5% CO2 gas mixture. Results -Eight to twelve minutes of O2/glucose deprivation induced an initial membrane hyperpolarization, followed by a delayed, large but reversible membrane depolarization. The depolarization phase was accompanied by a transient increase in [Ca2+](i) levels. When O2/glucose deprivation exceeded 13 to 15 minutes, both membrane depolarization and [Ca2+](i) rise became irreversible. The dihydropyridines nifedipine and nimodipine significantly reduced either the membrane depolarization or the [Ca2+](i) elevation. In contrast, tetrodotoxin had no effect on either of these parameters. Likewise, antagonists of ionotropic and group I and II metabotropic glutamate receptors failed to reduce the depolarization of the cell membrane and the [Ca2+](i) accumulation. Finally, dantrolene, blocker of intracellular Ca2+ release, did not reduce both electrical and [Ca2+](i) changes caused by O2/glucose depletion. Conclusions - This work supports a role of L-type Ca2+ channels both in the electrical and ionic changes occurring during the early phases of O2/glucose deprivation.
|Number of pages||7|
|Publication status||Published - Jan 1998|
- Calcium channels
- Fura 2
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine