title: A novel single-photon counting technique applied to highly sensitive measurement of [Ca2+]i transient in human aortic smooth muscle cells.
abstract: This study demonstrates that aequorin, a luminescent natural dye, is useful for vascular cell intracellular Ca2+ concentration ([Ca2+]i) determination. A new single-photon counting technique was developed to resolve the effects of fluid flow shear stress on [Ca2+]i in human aortic smooth muscle cells (HASMCs). Confluent HASMCs were grown on petri dishes loaded with aequorin. Then the dishes were placed in a luminometer chamber after the physiological level of shear stress was applied to the HASMC surfaces. The chamber was housed inside a highly sensitive photomultiplier tube. It detected ultraweak photon emission in response to the [Ca2+]i transient. In the presence of 2.0 mM extracellular Ca2+, a shear stress of 12 dyn cm2, applied for 60 s to the top surface of the HASMC monolayer, elicited a sharp increase in [Ca2+]i.
authors.affiliation: Energy Phenomena Laboratory, Department of Mechanical Engineering and Science, Tokyo Institute of Technology, 2-12-1 Meguro-ku, Tokyo 152-8859, Japan. stada@mech.titech.ac.jp
authors.forename: Shigeru
authors.initials: S
authors.lastname: Tada
authors.forename: Ken
authors.initials: K
authors.lastname: Okazaki
mesh_terms: D001011:Aorta / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002478:Cells, Cultured; D006801:Humans; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D017785:Photons; D011874:Radiometry / Q000379:methods*; D012680:Sensitivity and Specificity; D033081:Shear Strength; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D002118:Calcium