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Bending the MDCK Cell Primary Cilium Increases Intracellular Calcium

Bending the MDCK Cell Primary Cilium Increases Intracellular Calcium We tested the hypothesis that the primary cilium of renal epithelia is mechanically sensitive and serves as a flow sensor in MDCK cells using differential interference contrast and fluorescence microscopy. Bending the cilium, either by suction with a micropipette or by increasing the flow rate of perfusate, causes intracellular calcium to substantially increase as indicated by the fluorescent indicator, Fluo-4. This calcium signal is initiated by Ca2+-influx through mechanically sensitive channels that probably reside in the cilium or its base. The influx is followed by calcium release from IP3-sensitive stores. The calcium signal then spreads as a wave from the perturbed cell to its neighbors by diffusion of a second messenger through gap junctions. This spreading of the calcium wave points to flow sensing as a coordinated event within the tissue, rather than an isolated phenomenon in a single cell. Measurement of the membrane potential difference by microelectrode during perfusate flow reveals a profound hyperpolarization during the period of elevated intracellular calcium. We conclude that the primary cilium in MDCK cells is mechanically sensitive and responds to flow by greatly increasing intracellular calcium. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Bending the MDCK Cell Primary Cilium Increases Intracellular Calcium

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Publisher
Springer Journals
Copyright
Copyright © Inc. by 2001 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
DOI
10.1007/s00232-001-0075-4
Publisher site
See Article on Publisher Site

Abstract

We tested the hypothesis that the primary cilium of renal epithelia is mechanically sensitive and serves as a flow sensor in MDCK cells using differential interference contrast and fluorescence microscopy. Bending the cilium, either by suction with a micropipette or by increasing the flow rate of perfusate, causes intracellular calcium to substantially increase as indicated by the fluorescent indicator, Fluo-4. This calcium signal is initiated by Ca2+-influx through mechanically sensitive channels that probably reside in the cilium or its base. The influx is followed by calcium release from IP3-sensitive stores. The calcium signal then spreads as a wave from the perturbed cell to its neighbors by diffusion of a second messenger through gap junctions. This spreading of the calcium wave points to flow sensing as a coordinated event within the tissue, rather than an isolated phenomenon in a single cell. Measurement of the membrane potential difference by microelectrode during perfusate flow reveals a profound hyperpolarization during the period of elevated intracellular calcium. We conclude that the primary cilium in MDCK cells is mechanically sensitive and responds to flow by greatly increasing intracellular calcium.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Nov 1, 2001

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