Subcellular heterogeneity of voltage-gated Ca2+ channels in cells of the oligodendrocyte lineage.
We studied the distribution of voltage-gated Ca2+ channels in cells of the oligodendrocyte lineage from retinal and cortical cultures. Influx of Ca2+ via voltage-gated channels was activated by membrane depolarization with elevated extracellular K+ concentration ([K+]e) and local, subcellular increases in cytosolic free Ca2+ concentration ([Ca2+]in) could be monitored with a fluometric system connected to a laser scanning confocal microscope. In glial precursor cells from both retina and cortex, small depolarizations (with 10 or 20 mM K+) activated Ca2+ transients in processes indicating the presence of low-voltage-activated Ca2+ channels. Larger depolarizations (with 50 mM K+) additionally activated high-voltage-activated Ca2+ channels in the soma. An uneven distribution of Ca2+ channels was also observed in the mature oligodendrocytes; Ca2+ transients in processes were considerably larger. Recovery of Ca2+ levels after the voltage-induced influx was achieved by the activity of the plasmalemmal Ca2+ pump, while mitochondria played a minor role to restore Ca2+ levels after an influx through voltage-operated channels. During the development of white matter tracts, cells of the oligodendrocyte lineage contact axons to form myelin. Neuronal activity is accompanied by increases in [K+]e; this may lead to Ca2+ changes in the processes and the Ca2+ increases might be a signal for the glial precursor cell to start myelin formation.
Kirischuk
S
S
Max-Delbrück Center for Molecular Medicine, Berlin-Buch, Germany.
Scherer
J
J
Möller
T
T
Verkhratsky
A
A
Kettenmann
H
H
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000145:classification* / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000196:embryology; D005136:Eye Proteins / Q000145:classification / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D015640:Ion Channel Gating / Q000187:drug effects; D051379:Mice; D018613:Microscopy, Confocal; D009419:Nerve Tissue Proteins / Q000145:classification* / Q000502:physiology; D009836:Oligodendroglia / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000494:pharmacology; D012160:Retina / Q000166:cytology; D012433:Ryanodine / Q000494:pharmacology; D013234:Stem Cells / Q000187:drug effects / Q000502:physiology; D014700:Verapamil / Q000494:pharmacology
D015220:Calcium Channels; D005136:Eye Proteins; D009419:Nerve Tissue Proteins; D002104:Cadmium; D012433:Ryanodine; D014700:Verapamil; D011188:Potassium; D002118:Calcium