Mapping of IP(3)-mediated Ca(2+) signals in single human neuroblastoma SH-SY5Y cells: cell volume shaping the Ca(2+) signal.
Fast confocal laser-scanning microscopy was used to study spatiotemporal properties of IP(3)-mediated Ca(2+) release signals in human SH-SY5Y neuroblastoma cells. [Ca(2+)](i) increases were not affected by ryanodine (30 microgM) or caffeine (10 mM) and largely insensitive to removal of external Ca(2+), indicating predominance of IP(3)-induced Ca(2+) release. Ca(2+) signals evoked by high concentration (10 microM) of the muscarinic agonist carbachol appeared as self-propagating waves initiating in cell processes. At low carbachol concentrations (500 nM) Ca(2+) changes in most cells displayed striking spatiotemporal heterogeneity. The Ca(2+) response in the cell body was delayed and had a smaller amplitude and a slower rise time than that in processes. Ca(2+) changes in processes either occurred in a homogeneous manner throughout the whole process or were sometimes confined to hot spots. Regional differences in surface-to-volume ratio appear to be critical clues that determine the spatiotemporal pattern of intracellular Ca(2+) release signals.
van Acker
K
K
Laboratory of Physiology, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium.
Bautmans
B
B
Bultynck
G
G
Maes
K
K
Weidema
A F
AF
de Smet
P
P
Parys
J B
JB
de Smedt
H
H
Missiaen
L
L
Callewaert
G
G
D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000737:chemistry / Q000502:physiology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D048429:Cell Size / Q000502:physiology; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009447:Neuroblastoma; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000502:physiology; D014407:Tumor Cells, Cultured / Q000737:chemistry / Q000166:cytology / Q000502:physiology
D015220:Calcium Channels; D000697:Central Nervous System Stimulants; D018679:Cholinergic Agonists; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D002110:Caffeine; D015544:Inositol 1,4,5-Trisphosphate; D002217:Carbachol; D002118:Calcium