Arachidonic acid-induced calcium signalling in human airway smooth muscle cells.
The spatiotemporal distribution of Ca2+ signals evoked by arachidonic acid (AA) was investigated in human bronchial smooth muscle cells (SMC), using the single cell video imaging technique and Fura-2 as a fluorescent dye. Baseline Ca2+ levels were markedly heterogeneous in one and the same cell; the local Ca2 concentration laid between 90 +/- 11 and 215 +/- 18 nM (n = 15). AA (2 mM) induced propagating Ca2+ waves, travelling at a mean velocity of 18 +/- 3 microns/sec (n = 7). Ca2+ signals originated at discrete trigger zones, whose kinetic properties differed from those of neighbouring regions. Ca2+ in the trigger zones rose in two phases, with rates of 9.5 +/- 0.8 and 88 +/- 6 nM/sec (n = 17). A single cell frequently exhibited more than one trigger zones. In some cells, the wave did not reach all regions; such inert zones separated functionally the cell in independently active regions. Some regions presented Ca2+ signals that did not spread to the rest of the cell, forming isolated foci. The spatiotemporal variability of Ca2+ signals evoked by AA could result from the heterogeneity of Ca2+ homeostatic processes.
Colliard-Rouiller
C
C
Institut de Physiologie, Fribourg, Switzerland.
Durand
J
J
D016718:Arachidonic Acid / Q000494:pharmacology*; D001980:Bronchi / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D005071:Evoked Potentials / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects; D013050:Spectrometry, Fluorescence
D015220:Calcium Channels; D016718:Arachidonic Acid; D002118:Calcium