Depletion of intracellular Ca2+ stores or lowering extracellular calcium alters intracellular Ca2+ changes during cerebral energy deprivation

• Published in: Brain research 1998-06, Vol.796 (1-2), p.125-131
• Main Authors: GRØNDAHL, T. Ø, HABLITZ, J. J, LANGMOEN, I. A
• Format: Article
• Language: English
• Subjects: Aniline Compounds; Animals; Benzofurans; Biological and medical sciences; Calcium - metabolism; Calcium Channel Blockers - pharmacology; Energy Metabolism - physiology; Extracellular Space - metabolism; Fluorescent Dyes; Hippocampus - cytology; Hippocampus - drug effects; Hippocampus - metabolism; Imidazoles; In Vitro Techniques; Intracellular Membranes - metabolism; Medical sciences; Microscopy, Confocal; Neurology; Osmolar Concentration; Pyramidal Cells - drug effects; Pyramidal Cells - metabolism; Rats; Rats, Wistar; Thapsigargin - pharmacology; Vascular diseases and vascular malformations of the nervous system; Xanthenes
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/s0006-8993(98)00279-0

Cytoplasmatic calcium concentrations are elevated two to three fold during cerebral ischemia. In order to determine the role of calcium-release from intracellular stores vs. calcium entry from the extracellular space, intracellular stores were depleted by the use of thapsigargin and calcium was removed from the incubation fluid prior to energy deprivation (ED). CA 1 pyramidal neurons in hippocampal rat slices were filled with a 1:2 mixture of Fluo-3 and Fura Red by intracellular injection. The neurons were visualized in a Confocal Laser Scanning Microscope (CLSM) and the fluorescence ratio from the probe mixture was used to quantify the calcium concentration. Intracellular calcium concentration was monitored before and during ED. The intracellular calcium concentration was 55 nM prior to ED and increased to 25 microM during ED. The resting levels were the same in the experimental groups, but the increase during ED was significantly lower in the intervention groups. The increase in the calcium free group was to 1 microM and in the thapsigargin group to 5 microM. In the last experimental group, thapsigargin treatment and removal of extracellular calcium, the intracellular calcium increased to 630 nM. These results demonstrate that the increased intracellular calcium seen during ED originates from several sources. Calcium-release from intracellular stores may be of major importance in calcium-related neuronal injury during cerebral ischemia.