Multiple calcium patterns of rat osteoblasts under fluidic shear stress

The intracellular calcium ([Ca 2+ ] i ) response induced by external forces can be diverse and complex. Using primary osteoblasts from Wistar rats, we found multiple patterns of [Ca 2+ ] i responses induced by fluidic shear stress (Fss), including homogeneous non‐oscillation and heterogeneous oscillations. These multiple‐patterned [Ca 2+ ] i responses could be influenced by Fss intensity, cell density, and cell differentiation. Our real‐time measurements with free calcium, ATP, ATP without calcium, suramin, apyrase, and thapsigargin confirmed homogeneous [Ca 2+ ] i patterns and/or heterogeneous [Ca 2+ ] i oscillations with respect to the combined degree of external Ca 2+ influx, and intracellular Ca 2+ release. Our theoretical model supported diverse Fss‐induced calcium activities as well. We concluded that a singular factor of Ca 2+ influx or release dominated to produce smooth homogeneous patterns, but combined factors produced oscillatory heterogeneous patterns. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2039–2051, 2018.