title: TRP channel Ca(2+) sparklets: fundamental signals underlying endothelium-dependent hyperpolarization.
abstract: Important functions of the vascular endothelium, including permeability, production of antithrombotic factors, and control of vascular tone, are regulated by changes in intracellular Ca(2+). The molecular identities and regulation of Ca(2+) influx channels in the endothelium are incompletely understood, in part because of experimental difficulties associated with application of patch-clamp electrophysiology to native endothelial cells. However, advances in confocal and total internal reflection fluorescence microscopy and the development of fast, high-affinity Ca(2+)-binding fluorophores have recently allowed for direct visualization and characterization of single-channel transient receptor potential (TRP) channel Ca(2+) influx events in endothelial cells. These events, called "TRP channel Ca(2+) sparklets," have been optically recorded from primary endothelial cells and the intact endothelium, and the biophysical properties and fundamental significance of these Ca(2+) signals in vasomotor regulation have been characterized. This review will first briefly discuss the role of endothelial cell TRP channel Ca(2+) influx in endothelium-dependent vasodilation, describe improved methods for recording unitary TRP channel activity using optical methods, and highlight discoveries regarding the regulation and physiological significance of TRPV4 Ca(2+) sparklets in the vascular endothelium enabled by this new technology. Perspectives on the potential use of these techniques to evaluate changes in TRP channel Ca(2+) influx activity associated with endothelial dysfunction are offered.
authors.affiliation: Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada; and.
authors.forename: Michelle N
authors.initials: MN
authors.lastname: Sullivan
authors.forename: Scott
authors.initials: S
authors.lastname: Earley
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D004727:Endothelium / Q000502:physiology*; D008564:Membrane Potentials; D050051:Transient Receptor Potential Channels / Q000378:metabolism*
chemical_list: D050051:Transient Receptor Potential Channels; D002118:Calcium
keywords: Ca2+ sparklet; TRPV4; confocal microscopy; endothelium; total internal reflection fluorescence microscopy
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