Flow-induced calcium transients in single endothelial cells: spatial and temporal analysis.
Endothelial cells (EC) are uniquely situated to respond to hemodynamic forces. Because flow-mediated release of endothelial-derived relaxing factors is associated with increased EC intracellular calcium ([Ca2+]i), we sought to determine the effects of fluid shear stress on EC [Ca2+]i. Cells were subjected to flow in parallel-plate flow chambers and glass capillary tubes, and single cell [Ca2+]i was measured using fura-2. Upon initiation of flow (shear stress of 30 dyn/cm2), [Ca2+]i increased within 30 s to a peak value (approximately 4 times basal) and then decreased slowly to a plateau (approximately 2 times basal) that persisted for greater than 5 min. A striking finding was that the increases in [Ca2+]i were nonhomogeneous; the nuclear region and a periplasma membrane region were higher than the cytosol. After flow cessation, the increase in [Ca2+]i could be elicited repeatedly by resumption of flow. Removing extracellular Ca2+ did not eliminate the response. In contrast to EC, rat aortic smooth muscle cells showed no flow-mediated increase in [Ca2+]i. The complexity of EC [Ca2+]i response to flow suggests regulation of [Ca2+]i by several mechanisms that may serve a role in both short- and long-term EC responses to flow.
Geiger
R V
RV
School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332.
Berk
B C
BC
Alexander
R W
RW
Nerem
R M
RM
D000818:Animals; D001011:Aorta; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008856:Microscopy, Fluorescence; D008858:Microscopy, Phase-Contrast; D013314:Stress, Mechanical; D013997:Time Factors
D002118:Calcium