Bergmann glial cells in situ express endothelinB receptors linked to cytoplasmic calcium signals.
The endothelin (ET) isoforms ET-1, ET-2 and ET-3 applied at 100 nM triggered a transient increase in [Ca2+]i in Bergmann glial cells in cerebellar slices acutely isolated from 20-25 day-old mice. The intracellular calcium concentration ([Ca2+]i) was monitored using Fura-2-based [Ca2+]i microfluorimetry. The ET-triggered [Ca2+]i transients were mimicked by ETB receptor agonist BQ-3020 and were inhibited by ETB receptor antagonist BQ-788. ET elevated [Ca2+]i in Ca(2+)-free extracellular solution and the ET-triggered [Ca2+]i elevation was blocked by 500 nM thapsigargin indicating that the [Ca2+]i was released from InsP3-sensitive intracellular pools. The ET-triggered [Ca2+]i increase in Ca(2+)-free solution was shorter in duration. Restoration of normal extracellular [Ca2+] briefly after the ET application induced a second [Ca2+]i increase indicating the presence of a secondary Ca2+ influx which prolongs the Ca2+ signal. Pre-application of 100 microM ATP or 10 microM noradrenaline blocked the ET response suggesting the involvement of a common Ca2+ depot. The expression of ETB receptor mRNAs in Bergmann glial cells was revealed by single-cell RT-PCR. The mRNA was also found in Purkinje neurones, but no Ca2+ signalling was triggered by ET. We conclude that Bergmann glial cells are endowed with functional ETB receptors which induce the generation of intracellular [Ca2+]i signals by activation of Ca2+ release from InsP3-sensitive intracellular stores followed by a secondary Ca2+ influx.
Tuschick
S
S
Max-Delbrück Center for Molecular Medicine, Berlin-Buch, Germany.
Kirischuk
S
S
Kirchhoff
F
F
Liefeldt
L
L
Paul
M
M
Verkhratsky
A
A
Kettenmann
H
H
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000737:chemistry / Q000378:metabolism; D004594:Electrophysiology; D019332:Endothelin-1 / Q000494:pharmacology; D019334:Endothelin-3 / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D009457:Neuroglia / Q000737:chemistry* / Q000166:cytology / Q000187:drug effects; D011689:Purkinje Cells / Q000737:chemistry / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000819:agonists / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D019332:Endothelin-1; D019334:Endothelin-3; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D012333:RNA, Messenger; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D013779:Tetrodotoxin; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D002118:Calcium; D001640:Bicuculline