Mild acidosis inhibits the rise in intracellular Ca2+ concentration in response to oxygen-glucose deprivation in rat hippocampal slices.
Changes in the intracellular Ca2+ concentration ([Ca2+]i) induced by ischemia in vitro (oxygen-glucose deprivation) were continuously recorded using fura-2-loaded hippocampal slices under normal (pH 7.4), acidotic (pH 6.8) and alkalotic (pH 7.8) conditions. Oxygen-glucose deprivation induced an initial slow and a subsequent characteristic rapid increase in [Ca2+]i in most of the normal and alkalotic preparations regardless of whether or not Ca2+ was present in the bathing solutions. This characteristic rapid increase in [Ca2+]i was observed in a minority of the acidotic preparations and its latency was significantly longer in acidotic preparations than in normal and alkalotic preparations. The rise in [Ca2+]i at 10 min of oxygen-glucose deprivation was significantly smaller in the acidotic preparations than in the normal and alkalotic preparations, regardless of whether or not Ca2+ was present. At 15 min, the differences in the increase in [Ca2+]i between normal and acidotic preparations in Ca(2+)-containing solutions (2.5 mM) were insignificant. However, significant differences were still observed between the acidotic preparations and either the normal or alkalotic preparations under Ca(2+)-free conditions. These results suggest that acidosis inhibits the ischemia-induced rise in [Ca2+]i by attenuating both Ca2+ influx from the extracellular space and Ca2+ release from intracellular sites.
Department of Anesthesiology, Niigata University School of Medicine, Japan.
Y
Y
Ebine
N
N
Fujiwara
K
K
Shimoji
D000138:Acidosis; D000704:Analysis of Variance; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015687:Cell Hypoxia; D004533:Egtazic Acid / Q000494:pharmacology; D016257:Fura-2; D005947:Glucose / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D004533:Egtazic Acid; D005947:Glucose; D002118:Calcium; D016257:Fura-2