Fluid flow modulates vascular endothelial cytosolic calcium responses to adenine nucleotides.
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 Ca(2+)-sensitive dye fura-2, and placed in a parallel-plate flow chamber designed to generate defined laminar fluid flow. Cytosolic free Ca2+ concentration ([Ca2+]i) 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 microM) or ADP (0.1-1.0 microM) evoked repetitive oscillations in [Ca2+]i in individual BAEC. The frequency of the [Ca2+]i 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+]i oscillations. In the presence of nonhydrolyzable nucleotide analog, ATP gamma S or ADP beta S, application of flow resulted in similar shear-dependent [Ca2+]i oscillations, suggesting that flow modulation of the [Ca2+]i 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.
Shen
J
J
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Luscinskas
F W
FW
Gimbrone
M A
MA
Dewey
C F
CF
D000227:Adenine Nucleotides / Q000494:pharmacology*; D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000166:cytology; D001783:Blood Flow Velocity; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D013873:Thionucleotides / Q000494:pharmacology
D000227:Adenine Nucleotides; D013873:Thionucleotides; D000266:Adenylyl Imidodiphosphate; C030812:adenosine 5'-O-(2-thiodiphosphate); C022571:adenosine 5'-O-(3-thiotriphosphate); D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D002118:Calcium