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Visualizing the temporal effects of vasoconstrictors on PKC translocation and Ca2+ signaling in single resistance arterial smooth muscle cells

By Carl P. Nelson, Jonathon M. Willets, Noel W. Davies, R. A. John Challiss and Nicholas B. Standen

Abstract

This paper was published as American Journal of Physiology: Cell Physiology, 2008, 295 (6), pp. C1590-C1601. It is available from http://ajpcell.physiology.org/cgi/content/abstract/295/6/C1590. Doi: 10.1152/ajpcell.00365.2008Metadata only entryArterial smooth muscle (ASM) contraction plays a critical role in regulating blood distribution and blood pressure. Vasoconstrictors activate cell surface receptors to initiate signaling cascades involving increased intracellular Ca2+ concentration ([Ca2+]i) and recruitment of protein kinase C (PKC), leading to ASM contraction, though the PKC isoenzymes involved vary between different vasoconstrictors and their actions. Here, we have used confocal microscopy of enhanced green fluorescence protein (eGFP)-labeled PKC isoenzymes to visualize PKC translocation in primary rat mesenteric ASM cells in response to physiological vasoconstrictors, with simultaneous imaging of Ca2+ signaling. Endothelin-1, angiotensin II, and uridine triphosphate all caused translocation of each of the PKC isoenzymes , , and ; however, the kinetics of translocation varied between agonists and PKC isoenzymes. Translocation of eGFP-PKC mirrored the rise in [Ca2+]i, while that of eGFP-PKC or - occurred more slowly. Endothelin-induced translocation of eGFP-PKC was often sustained for several minutes, while responses to angiotensin II were always transient. In addition, preventing [Ca2+]i increases using 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra-(acetoxymethyl) ester prevented eGFP-PKC translocation, while eGFP-PKC translocated more rapidly. Our results suggest that PKC isoenzyme specificity of vasoconstrictor actions occurs downstream of PKC recruitment and demonstrate the varied kinetics and complex interplay between Ca2+ and PKC responses to different vasoconstrictors in ASM

Publisher: American Physiological Society
Year: 2008
DOI identifier: 10.1152/ajpcell.00365.2008
OAI identifier: oai:lra.le.ac.uk:2381/8053
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