Biophysical Journal 72: 1080-1091 (1997)
© 1997 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Li, Y X Articles by Rinzel, J Search for Related Content PubMed PubMed Citation Articles by Li, Y X Articles by Rinzel, J

Sensing and refilling calcium stores in an excitable cell.

Y X Li, S S Stojilkovi, J Keizer and J Rinzel

Mathematical Research Branch, National Institute of Arthritis, Diabetes, and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.

ABSTRACT

Inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ mobilization leads to depletion of the endoplasmic reticulum (ER) and an increase in Ca2+ entry. We show here for the gonadotroph, an excitable endocrine cell, that sensing of ER Ca2+ content can occur without the Ca2+ release-activated Ca2+ current (Icrac), but rather through the coupling of IP3-induced Ca2+ oscillations to plasma membrane voltage spikes that gate Ca2+ entry. Thus we demonstrate that capacitative Ca2+ entry is accomplished through Ca(2+)-controlled Ca2+ entry. We develop a comprehensive model, with parameter values constrained by available experimental data, to simulate the spatiotemporal behavior of agonist-induced Ca2+ signals in both the cytosol and ER lumen of gonadotrophs. The model combines two previously developed models, one for ER-mediated Ca2+ oscillations and another for plasma membrane potential-driven Ca2+ oscillations. Simulations show agreement with existing experimental records of store content, cytosolic Ca2+ concentration ([Ca2+]i), and electrical activity, and make a variety of new, experimentally testable predictions. In particular, computations with the model suggest that [Ca2+]i in the vicinity of the plasma membrane acts as a messenger for ER content via Ca(2+)-activated K+ channels and Ca2+ pumps in the plasma membrane. We conclude that, in excitable cells that do not express Icrac, [Ca2+]i profiles provide a sensitive mechanism for regulating net calcium flux through the plasma membrane during both store depletion and refilling.

This article has been cited by other articles:

				A. Khadra and Y.-X. Li A Model for the Pulsatile Secretion of Gonadotropin-Releasing Hormone from Synchronized Hypothalamic Neurons Biophys. J., July 1, 2006; 91(1): 74 - 83. [Abstract] [Full Text] [PDF]

				H. Zemkova, A. Balik, Y. Jiang, K. Kretschmannova, and S. S. Stojilkovic Roles of Purinergic P2X Receptors as Pacemaking Channels and Modulators of Calcium-Mobilizing Pathway in Pituitary Gonadotrophs Mol. Endocrinol., June 1, 2006; 20(6): 1423 - 1436. [Abstract] [Full Text] [PDF]

				J. M. A. M. Kusters, M. M. Dernison, W. P. M. van Meerwijk, D. L. Ypey, A. P. R. Theuvenet, and C. C. A. M. Gielen Stabilizing Role of Calcium Store-Dependent Plasma Membrane Calcium Channels in Action-Potential Firing and Intracellular Calcium Oscillations Biophys. J., December 1, 2005; 89(6): 3741 - 3756. [Abstract] [Full Text] [PDF]

				N. Hernjak, B. M. Slepchenko, K. Fernald, C. C. Fink, D. Fortin, I. I. Moraru, J. Watras, and L. M. Loew Modeling and Analysis of Calcium Signaling Events Leading to Long-Term Depression in Cerebellar Purkinje Cells Biophys. J., December 1, 2005; 89(6): 3790 - 3806. [Abstract] [Full Text] [PDF]

				D. Parthimos, D. H. Edwards, and T. M. Griffith Minimal model of arterial chaos generated by coupled intracellular and membrane Ca2+ oscillators Am J Physiol Heart Circ Physiol, September 1, 1999; 277(3): H1119 - H1144. [Abstract] [Full Text] [PDF]

				A. F. Fomina and M. C. Nowycky A Current Activated on Depletion of Intracellular Ca2+ Stores Can Regulate Exocytosis in Adrenal Chromaffin Cells J. Neurosci., May 15, 1999; 19(10): 3711 - 3722. [Abstract] [Full Text] [PDF]

				V. A. Tobin and B. J. Canny The Regulation of Gonadotropin-Releasing Hormone-Induced Calcium Signals in Male Rat Gonadotrophs by Testosterone Is Mediated by Dihydrotestosterone Endocrinology, March 1, 1998; 139(3): 1038 - 1045. [Abstract] [Full Text] [PDF]

				F. Van Goor, D. Zivadinovic, A. J. Martinez-Fuentes, and S. S. Stojilkovic Dependence of Pituitary Hormone Secretion on the Pattern of Spontaneus Voltage-gated Calcium Influx. CELL TYPE-SPECIFIC ACTION POTENTIAL SECRETION COUPLING J. Biol. Chem., August 31, 2001; 276(36): 33840 - 33846. [Abstract] [Full Text] [PDF]