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Mechanism of Mechanically Induced Intercellular Calcium Waves in Rabbit Articular Chondrocytes and in HIG‐82 Synovial Cells
Author(s) -
Grandolfo Micaela,
Calabrese Alessandra,
D'andrea Paola
Publication year - 1998
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1998.13.3.443
Subject(s) - intracellular , gap junction , extracellular , thapsigargin , microbiology and biotechnology , chemistry , stimulation , chondrocyte , calcium in biology , biophysics , biology , endocrinology , biochemistry , in vitro
Intercellular communication through gap junctions allows tissue coordination of cell metabolism and sensitivity to extracellular stimuli. Intercellular Ca 2+ signaling was investigated with digital fluorescence video imaging in primary cultures of articular chondrocytes and in HIG‐82 synovial cells. In both cell types, mechanical stimulation of a single cell induced a wave of increased Ca 2+ that was communicated to surrounding cells. Intercellular Ca 2+ spreading was inhibited by 18α‐glycyrrhetinic acid, demonstrating the involvement of gap junctions in signal propagation. In the absence of extracellular Ca 2+ , mechanical stimulation induced communicated Ca 2+ waves similar to controls; however, the number of HIG‐82 cells recruited decreased significantly. Mechanical stress induced Ca 2+ influx both in the stimulated chondrocyte and HIG‐82 cell, but not in the adjacent cells, as assessed by the Mn 2+ quenching technique. Treatment of cells with thapsigargin and with the phospholipase C (PLC) inhibitor U73122 blocked mechanically induced signal propagation. These results provide evidence that in chondrocytes and in HIG‐82 synovial cells, mechanical stimulation activates PLC, thus leading to an increase of intracellular inositol 1,4,5‐trisphosphate. The second messenger, by permeating gap junctions, stimulates intracellular Ca 2+ release in neighboring cells. It is concluded that intercellular Ca 2+ waves may provide a mechanism to coordinate tissue responses in joint physiology.