Spatial and temporal aspects of ACh-induced [Ca2+]i oscillations in porcine tracheal smooth muscle.
This study evaluated the relationship between regional elevation in intracellular calcium concentration ([Ca2+]i) induced by acetylcholine (ACh) and the global cellular responses in porcine tracheal smooth muscle (TSM) cells. Regional (approximately 1.5 microm3) and global (whole cell) changes in [Ca2+]i were measured in fluo-3 loaded TSM cells using real-time confocal microscopy. Regional responses appeared as propagating [Ca2+]i oscillations whereas global responses reflected the spatiotemporal integration of these regional responses. Within a region, [Ca2+]i oscillations were 'biphasic' with initial higher frequencies, followed by slower steady-state oscillations. With increasing ACh concentration, the peak (maximum value relative to 0 nM) of regional [Ca2+]i oscillations remained relatively constant, whereas both frequency and propagation velocity increased. In contrast, the global spatiotemporal integration of the regional oscillatory responses appeared as a concentration-dependent increase in peak as well as mean cellular [Ca2+]i. We conclude that the significance of ACh-induced [Ca2+]i oscillations lies in the establishment of mean [Ca2+]i level for slower Ca2+-dependent physiological processes via modulation of oscillation frequency and propagation velocity.
Prakash
Y S
YS
Department of Anesthesiology, Mayo Foundation, Rochester, MN 55905, USA.
Pabelick
C M
CM
Kannan
M S
MS
Sieck
G C
GC
D000109:Acetylcholine / Q000494:pharmacology*; D000704:Analysis of Variance; D000814:Aniline Compounds / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D003592:Cytophotometry; D004305:Dose-Response Relationship, Drug; D005456:Fluorescent Dyes / Q000378:metabolism; D007700:Kinetics; D018613:Microscopy, Confocal / Q000379:methods; D008954:Models, Biological; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D013552:Swine; D014132:Trachea; D014966:Xanthenes / Q000378:metabolism
D000814:Aniline Compounds; D005456:Fluorescent Dyes; D014966:Xanthenes; C059715:Fluo-3; D000109:Acetylcholine; D002118:Calcium