HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 285/2/C467    most recent 00042.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science 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 Web of Science (19) Citing Articles via Google Scholar Google Scholar Articles by He, M.-L. Articles by Stojilkovic, S. S. Search for Related Content PubMed PubMed Citation Articles by He, M.-L. Articles by Stojilkovic, S. S.

METHODS IN CELL PHYSIOLOGY

Intracellular calcium measurements as a method in studies on activity of purinergic P2X receptor channels

Mu-Lan He,^* Hana Zemkova,^* Taka-aki Koshimizu, Melanija Tomi, and Stanko S. Stojilkovic

Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4510

Submitted 29 January 2003 ; accepted in final form 22 April 2003

Extracellular nucleotide-activated purinergic receptors (P2XRs) are a family of cation-permeable channels that conduct small cations, including Ca²⁺, leading to the depolarization of cells and subsequent stimulation of voltage-gated Ca²⁺ influx in excitable cells. Here, we studied the spatiotemporal characteristics of intracellular Ca²⁺ signaling and its dependence on current signaling in excitable mouse immortalized gonadotropin-releasing hormone-secreting cells (GT1) and nonexcitable human embryonic kidney cells (HEK-293) cells expressing wild-type and chimeric P2XRs. In both cell types, P2XR generated depolarizing currents during the sustained ATP stimulation, which desensitized in order (from rapidly desensitizing to nondesensitizing): P2X₃R > P2X_2b + X₄R > P2X_2bR > P2X_2a + X₄R > P2X₄R > P2X_2aR > P2X₇R. HEK-293 cells were not suitable for studies on P2XR-mediated Ca²⁺ influx because of the coactivation of endogenously expressed Ca²⁺-mobilizing purinergic P2Y receptors. However, when expressed in GT1 cells, all wild-type and chimeric P2XRs responded to agonist binding with global Ca²⁺ signals, which desensitized in the same order as current signals but in a significantly slower manner. The global distribution of Ca²⁺ signals was present independently of the rate of current desensitization. The temporal characteristics of Ca²⁺ signals were not affected by voltage-gated Ca²⁺ influx and removal of extracellular sodium. Ca²⁺ signals reflected well the receptor-specific EC₅₀ values for ATP and the extracellular Zn²⁺ and pH sensitivities of P2XRs. These results indicate that intracellular Ca²⁺ measurements are useful for characterizing the pharmacological properties and messenger functions of P2XRs, as well as the kinetics of channel activity, when the host cells do not express other members of purinergic receptors.

ATP-gated receptor channels; inward currents; intracellular calcium signals; desensitization-inactivation; voltage-gated calcium influx; localized and global calcium signals

This article has been cited by other articles:

				S. Dolovcak, S. L. Waldrop, J. G. Fitz, and G. Kilic 5-Nitro-2-(3-phenylpropylamino)benzoic Acid (NPPB) Stimulates Cellular ATP Release through Exocytosis of ATP-enriched Vesicles J. Biol. Chem., December 4, 2009; 284(49): 33894 - 33903. [Abstract] [Full Text] [PDF]

				Z. Yan, S. Li, Z. Liang, M. Tomic, and S. S. Stojilkovic The P2X7 Receptor Channel Pore Dilates under Physiological Ion Conditions J. Gen. Physiol., October 27, 2008; 132(5): 563 - 573. [Abstract] [Full Text] [PDF]

				I. A. Khasabova, C. L. Stucky, C. Harding-Rose, L. Eikmeier, A. J. Beitz, L. G. Coicou, A. E. Hanson, D. A. Simone, and V. S. Seybold Chemical Interactions between Fibrosarcoma Cancer Cells and Sensory Neurons Contribute to Cancer Pain J. Neurosci., September 19, 2007; 27(38): 10289 - 10298. [Abstract] [Full Text] [PDF]

				X. Zhang, Y. Chen, C. Wang, and L.-Y. M. Huang Neuronal somatic ATP release triggers neuron-satellite glial cell communication in dorsal root ganglia PNAS, June 5, 2007; 104(23): 9864 - 9869. [Abstract] [Full Text] [PDF]

				T. M. Egan and B. S. Khakh Contribution of Calcium Ions to P2X Channel Responses J. Neurosci., March 31, 2004; 24(13): 3413 - 3420. [Abstract] [Full Text] [PDF]

				M.-L. He, A. E. Gonzalez-Iglesias, and S. S. Stojilkovic Role of Nucleotide P2 Receptors in Calcium Signaling and Prolactin Release in Pituitary Lactotrophs J. Biol. Chem., November 21, 2003; 278(47): 46270 - 46277. [Abstract] [Full Text] [PDF]