Detection of a trigger zone of bradykinin-induced fast calcium waves in PC12 neurites
| Autor: | Benno Schindelholz, Bernhard F.X. Reber |
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| Rok vydání: | 1996 |
| Předmět: |
Neurite
Physiology Clinical Biochemistry Bradykinin Inositol 1 4 5-Trisphosphate PC12 Cells Cell Line law.invention chemistry.chemical_compound Confocal microscopy law Caffeine Physiology (medical) Neurites Animals Inositol Nerve Growth Factors Growth cone Egtazic Acid Evoked Potentials Benzofurans Neurons Aniline Compounds Microscopy Confocal Phospholipase C Ryanodine Imidazoles Rats Xanthenes chemistry Biochemistry Biophysics Calcium Intracellular |
| Zdroj: | Pflügers Archiv - European Journal of Physiology. 432:893-903 |
| ISSN: | 1432-2013 0031-6768 |
| DOI: | 10.1007/s004240050213 |
| Popis: | Bradykinin and caffeine were used as two different agonists to study inositol 1,4,5-trisphosphate (IP3)-sensitive and caffeine/ryanodine-sensitive intracellular Ca2+ release in the outgrowing neurites of nerve-growth-factor (NGF)-treated rat phaeochromocytoma cells (PC12). Changes in neuritic intracellular free Ca2+ ([Ca2+]i) in single cells were measured after loading with a 1:1 mixture of the acetoxymethyl (AM) ester of the Ca2+-sensitive dyes Fura-red and Fluo-3, in combination with confocal microscopy. Bradykinin-induced Ca2+ release was blocked by U73211, a specific phospholipase C inhibitor. Caffeine-induced Ca2+ release was very low in neurites at rest. It increased after the cells were pre-loaded with Ca2+. The Ca2+ signal evoked at high concentrations of bradykinin (> 500 nM) arose from a trigger zone in the proximal part of the neurite, as a bi-direction-al wave towards the growth cone and cell body. The speed of neuritic Ca2+ waves was reduced in cells loaded with the Ca2+ chelator l,2-bis(2-aminophenoxy)ethane-tetraacetic acid/AM. Preloading of Ca2+ stores led to increased bradykinin-induced Ca2+ release, as seen for caffeine, and faster Ca2+ wave speeds. Caffeine evoked a simultaneous [Ca2+]i rise along the neurites of Ca2+ pre-loaded cells. Higher Ca2+ signal amplitudes and faster Ca2+ wave speeds, but no longer-lasting IP3-induced [Ca2+]i signals, correlated with increased caffeine-induced Ca2+ release in the neurites. At low concentrations of bradykinin (< 1.0 nM), the Ca2+ signals ceased to propagate as complete Ca2+ waves. Instead, repetitive stochastic Ca2+ release events (neuritic Ca2+ puffs) were observed. Neuritic Ca2+ puffs spread across only a few microns, at a slower speed than neuritic Ca2+ waves. These Ca2+ puffs represent elementary Ca2+ release units, whereby the released Ca2+ ions form these elementary events into the shape of a Ca2+ wave. |
| Databáze: | OpenAIRE |
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