Calcium-activated chloride channels in müller cells acutely isolated from tiger salamander retina.
Ca(2+)-activated chloride channels were identified with whole-cell patch-clamp recording techniques in salamander retinal Müller cells. Cl(Ca) channels were activated by membrane depolarizations that elicited Ca2+ influx or the application of the Ca2+ ionophore, ionomycin. The Ca channel blocker, Cd2+, abolished the Cl(Ca) channel tail currents. Increasing the duration of the depolarizing pulse resulted in enhancement of the Cl(Ca) channel tail current. Repetitive depolarizations with rapid pulses to +20 mV produced a buildup of I(Cl(Ca)), which reversed at 0 mV in symmetrical [Cl-] and at -40 mV when intracellular [Cl-] was reduced to 10% of the external concentration. I(Cl(Ca)) was blocked by the Cl channel blocker niflumic acid, while niflumic acid had no effect on voltage-gated Ca channels. These results offer the first demonstration of Cl(Ca) channels in a nonastrocytic glial cell and expand our understanding of the functional capacities of retinal glial cells.
Welch
Nicole C
NC
Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada.
Lalonde
Melanie R
MR
Barnes
Steven
S
Kelly
Melanie E M
ME
D000557:Ambystoma; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism*; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009457:Neuroglia / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D012160:Retina / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D018118:Chloride Channels; D007476:Ionophores; D015759:Ionomycin; D002118:Calcium