Endothelin-activated calcium signaling in enteric glia derived from neonatal guinea pig.
The ability of guinea pig enteric glia to respond to endothelins was examined using fura 2-based digital microscopy in glial cells derived from guinea pig taenia coli. Each isoform of endothelin (ET-1, ET-2, ET-3) evoked dose-dependent and equipotent increases in intracellular Ca2+ concentration ([Ca2+]i) and in percentage of cells responding, 4alaEt-1, an ETB receptor agonist, elicited similar [Ca2+]i increments. BQ-788, an ETB antagonist, inhibited [Ca2+]i responses to endothelin. Preincubation of glia with U-73122 a phospholipase C inhibitor, abolished the [Ca2+]i response to ET-3 exposure. Thapsigargin also eliminated ET-3-evoked Ca2+ signaling. The inositol 1,4,5-trisphosphate (IP3) receptor antagonist heparin, introduced into glial cells by radio frequency electroporation, blocked [Ca2+]i responses to ET-3 (100 nM) in 63% of glia. Sustained elevation in [Ca2+]i was abolished by removal of Ca2+ from the buffer and inhibited 85. -3% by Ni2+ (1 mM). Preincubation of glia with 100 nM phorbol 12-myristate 13-acetate (24 h) also inhibited sustained increments in [Ca2+]i by 87%. The presence of IP3 receptors in enteric glia was confirmed by immunofluorescent confocal microscopy.
Zhang
W
W
Department of Surgery, University of Michigan Medical School, Ann Arbor 48109-0331, USA.
Sarosi
G
G
Barnhart
D
D
Yule
D I
DI
Mulholland
M W
MW
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D016232:Endothelins / Q000494:pharmacology*; D005110:Extracellular Space / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006168:Guinea Pigs; D007150:Immunohistochemistry; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007422:Intestines / Q000294:innervation*; D008297:Male; D009457:Neuroglia / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D044023:Receptor, Endothelin B; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D017466:Receptors, Endothelin / Q000378:metabolism; D009418:S100 Proteins / Q000378:metabolism; D015398:Signal Transduction
D015220:Calcium Channels; D016232:Endothelins; D053496:Inositol 1,4,5-Trisphosphate Receptors; D044023:Receptor, Endothelin B; D018160:Receptors, Cytoplasmic and Nuclear; D017466:Receptors, Endothelin; D009418:S100 Proteins; D002118:Calcium