Intracellular Ca2+ stores and extracellular Ca2+ are required in the real-time Ca2+ response of bone cells experiencing fluid flow

Hung, C. T.; Allen, F. D.; Pollack, S. R.; Brighton, C. T.

Affiliations

¹Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, U.S.A.

²Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104, U.S.A.

Abstract and keywords

In this study, we sought to determine if there is a requirement for calcium entry from the extracellular space as well as calcium from intracellular stores to produce real-time intracellular calcium responses in cultured bone cells subjected to fluid flow. Understanding calcium cell signaling may help to elucidate the biophysical transduction mechanism(s) mediating the conversion of fluid flow to a cellular signal. An experimental design which utilized a scheme of pharmacological blockers was employed to distinguish between the biochemical pathways involved in this cell signaling. A parallel-plate flow chamber served as the cell stimulating apparatus and a fluorescence microscopy system using the calcium-sensitive dye fura-2 measured the intracellular calcium changes. In the present study, evidence for a role by the inositol-phospholipid biochemical pathway, specifically inositol trisphosphate (IP₃) was obtained using neomycin which completely inhibited the calcium response to flow. Additionally, a concomitant role of extracellular calcium was demonstrated through experiments performed in calcium-free medium which also eliminated the flow response. Experiments conducted with gadolinium, a stretch-activated channel blocker, partially inhibited (∼30%) the flow response while verapamil, a type-L voltage sensitive channel blocker, had no effect on the flow response. These results suggest a requirement of extracellular calcium (or calcium influx) as well as IP₃-induced calcium release from intracellular stores for generating the intracellular calcium response to flow in bone cells.

Keywords: Bone cell; Shear stress; Calcium; Fluid flow; Biochemical pathway

Links

DOI: 10.1016/0021-9290(96)84536-2

PubMed: 8894921

WoS: A1996VK71200002

History

Received: 1996-04-15

Revised: 1996-11-1

Cited Works (7)

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Cited By (42)

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