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Journal Article

Rhythmic exocytosis stimulated by GnRH-induced calcium oscillations in rat gonadotropes


Almers,  Wolfhard
Department of Molecular Cell Research, Max Planck Institute for Medical Research, Max Planck Society;

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Tse, A., Tse, F. W., Almers, W., & Hille, B. (1993). Rhythmic exocytosis stimulated by GnRH-induced calcium oscillations in rat gonadotropes. Science, 260(5104), 82-84. doi:10.1126/science.8385366.

Cite as: http://hdl.handle.net/11858/00-001M-0000-0019-AA86-3
In pituitary gonadotropes, gonadotropin-releasing hormone (GnRH) induces the rhythmic release of Ca2+ from an inositol 1,4,5-trisphosphate (IP3)-sensitive store. Simultaneous measurement of the concentration of cytosolic free Ca2+ ([Ca2+]i) and exocytosis in single identified gonadotropes showed that each elevation of [Ca2+]i induced a burst of exocytosis. These phenomena were largely suppressed by buffering of [Ca2+]i but persisted in the absence of extracellular Ca2+. Activation of voltage-gated Ca2+ channels by brief depolarizations seldom supplied enough Ca2+ for exocytosis, but [Ca2+]i elevations induced by photolysis of caged IP3 did trigger exocytosis, confirming that GnRH-stimulated gonadotropic hormone secretion is closely coupled to intracellular Ca2+ release. Agonist-induced oscillations of [Ca2+]i in secretory cells may be a mechanism to optimize the secretory output while avoiding the toxic effects of sustained elevation of [Ca2+]i.