title: Effects of fluid flow on intracellular calcium in bovine articular chondrocytes.
abstract: Fluid flow-induced shear stress results in a variety of morphological and metabolic changes in cultured bovine articular chondrocytes (BAC). However, the mechanism by which the flow signal is transduced into a biological response is unknown. Therefore, we investigated the effects of fluid flow on intracellular Ca2+ concentration ([Ca2+]i) in BAC. Cells loaded with fura 2 were exposed to steady and pulsatile (0.5 Hz) flow at 9, 18, and 34 ml/min in a parallel-plate flow chamber. In response to flow, there was a significant and flow rate-dependent increase in the percentage of cells showing a rise in [Ca2+]i, but no effect on the [Ca2+]i response amplitude. There was no significant difference between the [Ca2+]i responses to steady and pulsatile flow. Mean intracellular Ca2+ response values ranged between 26.2 +/- 1.6 (9 ml/min) and 38.0 +/- 6.8 nM (34 ml/min) above basal [Ca2+]i (81.3 +/- 24.1 nM, n = 90). Removal of extracellular Ca2+ or addition of Gd3+ significantly reduced the percentage of cells responding, suggesting that influx of Ca2+, possibly through mechanosensitive channels, contributes to the rise in intracellular Ca2+. Our data suggest fluid flow-induced mobilization of intracellular Ca2+ may contribute to the mechanism by which mechanical loads are transduced by chondrocytes.
authors.affiliation: Department of Orthopaedics and Rehabilitation, Pennsylvania State University College of Medicine, Hershey 17033, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Yellowley
authors.forename: C R
authors.initials: CR
authors.lastname: Jacobs
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.forename: Z
authors.initials: Z
authors.lastname: Zhou
authors.forename: H J
authors.initials: HJ
authors.lastname: Donahue
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis*; D004533:Egtazic Acid / Q000494:pharmacology; D019084:Fluorescent Antibody Technique, Indirect; D016257:Fura-2; D005682:Gadolinium / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology; D007700:Kinetics; D013314:Stress, Mechanical; D013997:Time Factors
chemical_list: D007473:Ion Channels; D004533:Egtazic Acid; D003094:Collagen; D005682:Gadolinium; D002118:Calcium; D016257:Fura-2