Examination of the role of transient receptor potential vanilloid type 4 in endothelial responses to shear forces     

Sara Baratchi  Francisco J. Tovar-Lopez  Khashayar Khoshmanesh  Megan S. Grace  William Darby  Juhura Almazi  Arnan Mitchell  Peter McIntyre 《Biomicrofluidics》2014,8(4)

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 ([Ca²⁺]_i) using the fluorescent calcium sensitive dye Fluo-4AM. Shear stress caused an elevation of [Ca²⁺]_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 [Ca²⁺]_i are largely due to calcium influx through the transient receptor potential vanilloid type 4 ion channel.  相似文献