title: Dual action of cytosolic calcium on calcium channel activity during hypoxia in hippocampal neurones.
abstract: The role of cytoplasmic calcium level (Ca(i)) in regulation of Ca channel activity during hypoxia was studied in hippocampal neurones from rats. Whole-cell patch clamp recordings in combination with measurements of O(2) partial pressure (pO(2)) were used. Lowering of pO(2) induced a potentiation of HVA Ca channel activity by 25.7% at Ca(i) = 75 nM in comparison with Ca(2+)-free solution. Increase of Ca(i) up to 410 nM slightly increased the effect and significantly slowed the Ca(2+) current run-down. On the other hand, hypoxia increased a steady-state channel inactivation and speeded up the kinetics of Ca(2+) current decay by about 30%. We conclude that moderate hypoxia induces dual action on Ca channels: intracellularly mediated augmentation of Ca influx via Ca channels and their Ca(2+)-dependent inactivation.
authors.affiliation: Department of General Physiology of Nervous System, Bogomoletz Institute of Physiology, Bogomoletz str. 4, Kiev 01024, Ukraine.
authors.forename: V M
authors.initials: VM
authors.lastname: Shkryl
authors.forename: P G
authors.initials: PG
authors.lastname: Kostyuk
authors.forename: E A
authors.initials: EA
authors.lastname: Lukyanetz
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology*; D002534:Hypoxia, Brain / Q000378:metabolism* / Q000503:physiopathology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar
chemical_list: D015220:Calcium Channels; D002118:Calcium