Examination of the role of transient receptor potential vanilloid type 4 in endothelial responses to shear forces.
Shear stress is the major mechanical force applied on vascular endothelial cells by blood flow, and is a crucial factor in normal vascular physiology and in the development of some vascular pathologies. The exact mechanisms of cellular mechano-transduction in mammalian cells and tissues have not yet been elucidated, but it is known that mechanically sensitive receptors and ion channels play a crucial role. This paper describes the use of a novel and efficient microfluidic device to study mechanically-sensitive receptors and ion channels in vitro, which has three independent channels from which recordings can be made and has a small surface area such that fewer cells are required than for conventional flow chambers. The contoured channels of the device enabled examination of a range of shear stresses in one field of view, which is not possible with parallel plate flow chambers and other previously used devices, where one level of flow-induced shear stress is produced per fixed flow-rate. We exposed bovine aortic endothelial cells to different levels of shear stress, and measured the resulting change in intracellular calcium levels ([Ca(2+)]i) using the fluorescent calcium sensitive dye Fluo-4AM. Shear stress caused an elevation of [Ca(2+)]i that was proportional to the level of shear experienced. The response was temperature dependant such that at lower temperatures more shear stress was required to elicit a given level of calcium signal and the magnitude of influx was reduced. We demonstrated that shear stress-induced elevations in [Ca(2+)]i are largely due to calcium influx through the transient receptor potential vanilloid type 4 ion channel.
Sara
S
Baratchi
Microplatforms Research Group, School of Electrical and Computer Engineering, RMIT University , Victoria 3001, Australia.
Francisco J
FJ
Tovar-Lopez
Microplatforms Research Group, School of Electrical and Computer Engineering, RMIT University , Victoria 3001, Australia.
Khashayar
K
Khoshmanesh
Health Innovations Research Institute, RMIT University , Victoria 3083, Australia.
Megan S
MS
Grace
Health Innovations Research Institute, RMIT University , Victoria 3083, Australia.
William
W
Darby
Health Innovations Research Institute, RMIT University , Victoria 3083, Australia.
Juhura
J
Almazi
Microplatforms Research Group, School of Electrical and Computer Engineering, RMIT University , Victoria 3001, Australia.
Arnan
A
Mitchell
Health Innovations Research Institute, RMIT University , Victoria 3083, Australia.
Peter
P
McIntyre