High-threshold calcium channel activity in rat hippocampal neurones during hypoxia.
Whole-cell patch clamp recordings in combination with direct control and measurements of O2 tension (pO2) in bath solution were used to determine the sensitivity of Ca2+ channels of cultured hippocampal neurones to hypoxia in glucose free solution. In all tested neurones, a lowering of pO2 to 4/50 mmHg did not induce changes either in magnitude, kinetics or voltage-current relations of total Ca2+ currents, which composed mainly from two types, L-type (64%) and N-type (31%) components. Hypoxia only induced a delay of Ca2+ current run-down about 27.5% and 39% at 50 and 4 mmHg pO2 respectively that presumably depended on changes in cytoplasmic channel-modulatory metabolites. The obtained results demonstrate that Ca2+ channel molecules in cultured hippocampal neurones are themselves insensitive to short-lasting (10-20 min) oxygen and glucose deprivation, and that they are not a principal target for hypoxic influences on hippocampal function.
Shkryl
V M
VM
Department of General Physiology of Nervous System, Bogomoletz Institute of Physiology, Bogomoletz str. 4, 252024, Kiev, Ukraine.
Nikolaenko
L M
LM
Kostyuk
P G
PG
Lukyanetz
E A
EA
D000818:Animals; D000831:Animals, Newborn; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D006624:Hippocampus / Q000098:blood supply / Q000166:cytology*; D007003:Hypoglycemia / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology*; D002534:Hypoxia, Brain / Q000503:physiopathology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000737:chemistry* / Q000502:physiology; D009543:Nifedipine / Q000494:pharmacology; D010100:Oxygen / Q000032:analysis; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010455:Peptides; D002104:Cadmium; D020866:omega-Conotoxin GVIA; D009543:Nifedipine; D010100:Oxygen; D002118:Calcium