Fei Wei, Xiaomin Shi, Jiyao Chen, Luwei Zhou Fluid shear stress-induced cytosolic calcium and degranulation dynamics in mast cell Fei Wei, Xiaomin Shi, Jiyao Chen, Luwei Zhou State Key Laboratory of Surface Physics and Department of Physics, Fudan University There is hypothesis that shear stress caused by needle acupuncture and massage may induce calcium increase and histamine release in mast cells, thereby improving the local tissue microcirculation of blood. In the present work, a mast cell line (rat basophilic leukemia cells, RBL-2H3) was used in vitro to study cellular responses to the stimulus of fluid shear stress generated by a rotating rotor in a cell dish. The intracellular calcium was studied by confocal fluorescence microscopy with Fluo-3/AM staining. The calcium oscillate or increase immediately after fluid shear stress was exerted by rotating rotor. From mathematical model we can reproduce calcium and degranulation dynamics in mast cell under fluid shear stress. Calcium dynamics presents a steady and oscillating states in mast cells according to different shear stress, and degranlation increase with shear stress, suggesting that mast cells are so sensitive to the stimulus of shear stress. Calcium increase and histamine release of mast cells under shear stress are important in understanding the mechanism of acupuncture and massage. I. Experiment Experimental method Fluorescence Measurements of [Ca2+]c stained with fluo-3/AM [Ca2+]c fluorescence intensities in a cell under fluid shear stress that is 1.2×10-2 Pa [Ca2+]c fluorescence intensities in a cell under fluid shear stress that is 3×10-2 Pa [Ca2+]c fluorescence intensities in a cell under fluid shear stress that is 3×10-2 Pa Confocal fluorescence microscopy (DSU,IX-71 Olympus) Fluid shear stress II. Model Numerical calculation result of cytosolic calcium concentration c(t) under the shear stress =3 Pa comparing with experiment data Mathematical model Under the shear stress =1.4 Pa, cytosolic calcium concentration c(t) change with time shear stress-induced calcium channel open probability Cytosolic calcium dynamics c(t) : Cytosolic calcium concentration ce(t): ER calcium concentration c(0)=0.1M, ce(0)=2.5 M Degranulation dynamics Under the shear stress =3-5.5 Pa, cytosolic calcium concentration c(t) changes with time. Degranulation dynamics of mast cells under fluid shear stress P1 (t) denotes the activated protein kinase C (PKC) concentration P2(t) the rate of phosphorylated synaptosomal-associated protein 23 (SNAP-23) P3(t) the degranulation rate III. conclusions Explore cytosolic calcium dynamics of mast cells under fluid shear stress by confocal fluorescence microscopy, and establish a mathematical model of calcium and degranulation dynamics of mast cells under fluid shear stress to compare with experiments. Calcium dynamics presents a steady and oscillating states in mast cells according to different shear stress. Calcium oscillations exist under less shear stress, but steady calcium states appear under larger shear stress. Experiments are qualitatively consistent with numerical results. Reference: Wenzhong Yang. et al. Effects of Shear Stress on Intracellular Calcium Change and Histamine Release in Rat Basophilic Leukemia (RBL-2H3) Cells. Journal of Environmental Pathology, Toxicology and Oncology. 2009, 28 (3), p:223-230. Shi XiaoMin et al. A model of calcium signaling and degranulation dynamics induced by laser irradiation in mast cells. Chinese Science Bulletin. 2008, 53 (15), p:2315-2325. Theodore F et al. A mathematical model of the cytosolic-free calcium response in endothelial cells to fluid shear stress. Proc. Natl. Acad. Sci. 1997, 94, p:3726-3731.