Spatial and temporal control of intracellular free Ca2+ in chick sensory neurons

• Published in: Pflügers Archiv Vol. 424; no. 2; pp. 183 - 191
• Main Authors: MIRONOV, S. L, USACHEV, YU. M, LUX, H. D
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Heidelberg Springer 01-07-1993
• Subjects: Animals; Biological and medical sciences; Caffeine - pharmacology; Calcium - metabolism; Calcium Channels - drug effects; Calcium Channels - metabolism; Calcium-Transporting ATPases - antagonists & inhibitors; Cells, Cultured; Central nervous system; Chick Embryo; Electrophysiology; Fundamental and applied biological sciences. Psychology; Ganglia, Spinal - cytology; Ganglia, Spinal - drug effects; Ganglia, Spinal - metabolism; Neurites - drug effects; Neurites - metabolism; Neurons, Afferent - drug effects; Neurons, Afferent - metabolism; Potassium Chloride - pharmacology; Spectrometry, Fluorescence; Terpenes - pharmacology; Thapsigargin; Vertebrates: nervous system and sense organs; Cell compartment; Cell culture; Spinal cord; Calcium; Free ion; Central nervous system; Electrophysiology; Depolarization; Vertebrata; Regulation(control); Sensory neuron; Spinal ganglion; Chicken; Intracellular; Membrane potential; Aves
• ISSN: 0031-6768; 1432-2013
• DOI: 10.1007/BF00374610

Digital imaging of fura-2 fluorescence and the voltage-clamp technique were combined to study cytoplasmic free Ca2+ concentration, [Ca]i, in neurons cultured from chick dorsal root ganglia. Depolarizing pulses raised [Ca]i to a new steady-state level which was achieved earlier in neurites than in the soma. The rise in [Ca]i during stimulated bursting or rhythmic activity was also faster in neurites. After stimulation [Ca]i recovered monoexponentially in the soma and biexponentially in neurites. Application of 50 mM KCl produced membrane depolarization and a concomitant increase of [Ca]i. During wash-out [Ca]i often declined to an intermediate steady-state level at which it stayed for several minutes. Thereafter the resting level of [Ca]i was quickly restored. [Ca]i recovery was delayed after treating the cell with 2 microM thapsigargin, an inhibitor of the Ca2+ pump of internal Ca2+ stores. Caffeine (10 mM) transiently increased [Ca]i. A second caffeine application produced smaller [Ca]i changes due to the prior depletion of Ca2+ stores, which could be replenished by brief exposure to KCl. Thapsigargin (2 microM) transiently increased [Ca]i both in the standard and Ca(2+)-free solution. [Ca]i transients due to caffeine and thapsigargin started in the cell interior, in contrast to [Ca]i changes evoked by membrane depolarization, which were noticed first at the cell edge. Caffeine and thapsigargin induced a transient inward current which persisted in the presence of 1 mM La3+ and in Ca(2+)-free solutions, but which was greatly diminished in Na(+)-free solutions. The effects of caffeine and thapsigargin were mutually exclusive both in the generation of [Ca]i transients and in the inward current induction.