Fluid Flow Modulates Vascular Endothelial Cytosolic Calcium Responses to Adenine Nucleotides

Authors

  • Jian Shen,

    1. Fluid Mechanics Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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  • Francis W. Luscinskas,

    1. Vascular Research Division, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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  • Michael A Gimbrone Jr.,

    1. Vascular Research Division, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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  • Dr. C. Forbes Dewey Jr.

    Corresponding author
    1. Fluid Mechanics Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Room 3–250, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, 02139, USA

ABSTRACT

Objective: To determine whether fluid flow influences the action of soluble vasoactive agonists on vascular endothelium.

Methods: Confluent monolayers of bovine aortic endothelial cells (BAEC) were cultured on glass coverslips, prelabeled with the Ca2+-sensitive dye fura-2, and placed in a parallel-plate flow chamber designed to generate defined laminar fluid flow. Cytosolic free Ca2+ concentration ([Ca2+];) in individual BAEC was monitored during perfusion with medium containing adenine nucleotide under defined flow conditions.

Results: Continuous perfusion with ATP (0.3–3.0 μM) or ADP (0.1–1.0 μM) evoked repetitive oscillations in [Ca2+]; in individual BAEC. The frequency of the [Ca2+]; oscillations was dependent on both nucleotide concentration and levels of applied shear stress; at constant bulk concentration of nucleotide, the frequency increased with shear stress. Stopping flow in the continuous presence of agonists immediately extinguished the oscillatory response. Elimination of extracellular Ca2+ did not inhibit the [Ca2+]; oscillations. In the presence of nonhydrolyzable nucleotide analog, ATPγS or ADPβS, application of flow resulted in similar shear-dependent [Ca2+]; oscillations, suggesting that flow modulation of the [Ca2+]; response was not simply due to depletion of ATP or ADP in the vicinity of BAEC monolayers as a result of hydrolysis of nucleotides by ectonucleotidases.

Conclusions: These findings suggest that local hemodynamic conditions may modulate the action of vasoactive agents on the vascular endothelium in vivo.

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