Propagation of calcium waves between colonic smooth muscle cells in culture.
Intercellular propagation of a diffusible substance through direct cytoplasmic communication between multiple cells could represent an important mechanism for mutual multiple cell signaling between cells in a tissue. The current study was aimed at characterizing the mechanism(s) underlying the intercellular propagation of calcium concentration ([Ca2+]i) transients between colonic smooth muscle cells. Changes in [Ca2+]i in smooth muscle cells from the rabbit distal colon in primary cultures were monitored using videomicroscopy with the fluorescent dye Fura-2. Myocytes responded to light mechanical deformation of the plasma membrane with a localized increase in [Ca2+]i which spread in a wave-like fashion through up to 5 adjacent cells, with little change in wave amplitude. Dye coupling between cells was demonstrated by Lucifer Yellow, and intercellular wave propagation was abolished by octanol, suggesting propagation of Ca2+ waves via gap junctions. Wave propagation was not dependent on extracellular [Ca2+]i suggesting regenerative release of Ca2+ from intracellular stores. Propagation of Ca2+ waves through silent cells suggested a diffusible messenger other than Ca2+. Wave propagation and kinetics were unaffected by ryanodine (50 microM) or caffeine (10 mM), but abolished by depletion of thapsigargin-sensitive Ca2+ stores and by the phospholipase C inhibitor U-73122 (10 microM), implicating inositol 1,4,5-trisphosphate (Ins(1,4,5)P3)-sensitive stores as the major Ca2+ source for propagated Ca2+ transients. These results indicate that, in a connected complex of colonic smooth muscle cells in culture, multiple cells can monitor the mechanical status of a single cell through diffusion of Ins(1,4,5)P3, Ca2+, or another intercellular messenger.
Department of Medicine, University of California at Los Angeles, USA. shyoung@ucla.edu
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Young
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Ennes
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Mayer
D000818:Animals; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D002478:Cells, Cultured; D005456:Fluorescent Dyes; D016257:Fura-2; D018715:Microscopy, Video; D009130:Muscle, Smooth / Q000378:metabolism*; D011817:Rabbits
D005456:Fluorescent Dyes; D002118:Calcium; D016257:Fura-2