Dose-dependency in spatial dynamics of [Ca2+]c in pancreatic acinar cells.
Spatial dynamics of cytosolic concentration of Ca2+, [Ca2+]c, in stimulus-secretion coupling of rat pancreatic acinar cell was monitored by a digital image analysing technique using Fura-2. When freshly isolated acini were stimulated with lower concentrations of CCK-8 (5-30 pM), [Ca2+]c increase began at the region beneath the basolateral membrane and the [Ca2+]c increase depended on the presence of extracellular Ca2+ ([Ca2+]o). CCK-8 at higher concentrations (100 pM and 1 nM), however, caused [Ca2+]c increase even in the absence of [Ca2+]o. Low concentrations of G-protein activator, NaF (10 mM or lower), caused [Ca2+]o-dependent increase in [Ca2+]c, whereas higher concentrations of NaF (15 mM or higher) increased [Ca2+]c in the absence of [Ca2+]o. These results are compatible with the view that G-protein activated by a physiological concentration of secretagogue accelerates Ca2+ entry. This process is in contrast to the process of Ca2+ release from intracellular stores, which can be predominant when pharmacological or toxic concentration of the secretagogue was applied.
Habara
Y
Y
Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
Kanno
T
T
D000818:Animals; D002118:Calcium / Q000032:analysis / Q000493:pharmacokinetics* / Q000494:pharmacology*; D002462:Cell Membrane / Q000737:chemistry / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D002766:Cholecystokinin / Q000494:pharmacology; D003600:Cytosol / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D005453:Fluorescence; D016257:Fura-2; D019204:GTP-Binding Proteins / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D008297:Male; D010179:Pancreas / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D012844:Sincalide / Q000494:pharmacology; D012969:Sodium Fluoride / Q000494:pharmacology
D012969:Sodium Fluoride; D002766:Cholecystokinin; D019204:GTP-Binding Proteins; D012844:Sincalide; D002118:Calcium; D016257:Fura-2