Propagation of intercellular Ca2+ waves in mechanically stimulated articular chondrocytes.
Intercellular Ca2+ signalling in primary cultures of articular chondrocytes was investigated with digital fluorescence video imaging. Mechanical stimulation of a single cell induced a wave of increased Ca2+ that was communicated to surrounding cells. Intercellular Ca2+ spreading was inhibited by 18alpha-glycyrrhetinic acid, demonstrating the involvement of gap junctions in signal propagation. In the absence of extracellular Ca2+ mechanical stimulation failed to induce Ca2+ responses and communicated Ca2+ waves. Under these conditions Ca2+ microinjection induced intercellular waves involving the cells immediately surrounding the stimulated one. Mechanical stress induced Ca2+ influx in the stimulated, but not in the adjacent cells, as assessed by the Mn2+ quenching technique. Cell treatment with thapsigargin failed to block mechanically induced signal propagation, but significantly reduced the number of cells involved in the communicated Ca2+ wave. Similar results were obtained with the phospholipase C inhibitor U73122, which is known to prevent InsP3 generation. These results provide evidence that mechanical stimulation induces a cytosolic Ca2+ increase that may permeate gap junctions, thus acting as an intercellular messenger mediating cell-to-cell communication in articular chondrocytes.
D'Andrea
P
P
Dipartimento di Biochimica, Biofisica e Chimica delle Macromolecole, Università di Trieste, Italy. dandrea@univ.trieste.it
Vittur
F
F
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D007091:Image Processing, Computer-Assisted; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D010726:Phosphodiesterase Inhibitors; D010812:Physical Stimulation; D011760:Pyrrolidinones / Q000494:pharmacology; D015398:Signal Transduction; D013552:Swine; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D004791:Enzyme Inhibitors; D004963:Estrenes; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D019284:Thapsigargin; D010738:Type C Phospholipases; D000252:Calcium-Transporting ATPases; D002118:Calcium