Synchronized spontaneous Ca2+ transients in acute anterior pituitary slices.
We investigated the organization of spontaneous rises in cytosolic free Ca2+ concentration ([Ca2+]i) due to electrical activity in acute pituitary slices. Real time confocal imaging revealed that 73% of the cells generated fast peaking spontaneous [Ca2+]i transients. Strikingly, groups of apposing cells enhanced their [Ca2+]i in synchrony with a speed of coactivation >1,000 microm/s. Single-cell injection of Neurobiotin or Lucifer yellow labeled clusters of cells, which corresponded to coactive cells. Halothane, a gap junction blocker, markedly reduced the spread of tracers. Coupling between excitable cells was mainly homologous in nature, with a prevalence of growth hormone-containing cells. We conclude that spontaneously active endocrine cells are either single units or arranged in synchronized gap junction-coupled assemblies scattered throughout the anterior pituitary gland. Synchrony between spontaneously excitable cells may help shape the patterns of basal secretion.
Guérineau
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NC
INSERM U469, Centre CNRS/INSERM de Pharmacologie et d'Endocrinologie, 141 rue de la Cardonille, 34094 Montpellier Cedex 5, France. guerinea@u469.montp.inserm.fr
Bonnefont
X
X
Stoeckel
L
L
Mollard
P
P
D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D004396:Coloring Agents / Q000378:metabolism; D004058:Diffusion; D005260:Female; D013006:Growth Hormone / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D017136:Ion Transport; D007546:Isoquinolines / Q000378:metabolism; D007700:Kinetics; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*
D004396:Coloring Agents; D007546:Isoquinolines; C070614:neurobiotin; D001710:Biotin; D013006:Growth Hormone; C017475:lucifer yellow; D002118:Calcium