Ca2+ sparks and Ca2+ glows in superior cervical ganglion neurons.
OBJECTIVE
Ca2+ release from the endoplasmic reticulum (ER) is an integral component of neuronal Ca2+ signaling. The present study is to investigate properties of local Ca2+ release events in superior cervical ganglion (SCG) neurons.


METHODS
Primary cultured SCG neurons were prepared from neonatal rats (P3-P7). Low concentration of caffeine was used to induce Ca2+ release from the ER Ca2+ store, and intracellular Ca2+ was recorded by high-resolution line scan confocal imaging and the Ca2+ indicator Fluo-4.


RESULTS
Two populations of local Ca2+ release events with distinct temporal characteristics were evoked by 1.5 mmol/L caffeine near the surface membrane in the soma and the neurites of SCG neurons. Brief events similar to classic Ca2+ sparks lasted a few hundreds of milliseconds, whereas long-lasting events displayed duration up to tens of seconds. Typical somatic and neurite sparks were of 0.3- and 0.52-fold increase in local Fluo-4 fluorescence, respectively. Typical Ca2+ glows were brighter (deltaF/F0 approximately 0.6), but were highly confined in space. The half maximum of full duration of neurite sparks was much longer than those in the soma (685 vs 381 ms).


CONCLUSIONS
Co-existence of Ca2+ sparks and Ca2+ glows in SCG neurons indicates distinctive local regulation of Ca2+ release kinetics. The local Ca2+ signals of variable, site-specific temporal length may bear important implications in encoding a 'memory' of the trigger signal.
Yao
Li-jun
LJ
Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou 310031, China.
Wang
Gang
G
Ou-Yang
Kun-fu
KF
Wei
Chao-liang
CL
Wang
Xian-hua
XH
Wang
Shi-rong
SR
Yao
Wei
W
Huang
Hong-ping
HP
Luo
Jian-hong
JH
Wu
Cai-hong
CH
Liu
Jie
J
Zhou
Zhuan
Z
Cheng
He-ping
HP
D000818:Animals; D000831:Animals, Newborn; D002110:Caffeine / Q000037:antagonists & inhibitors; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D051381:Rats; D017783:Superior Cervical Ganglion / Q000166:cytology / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology
D002110:Caffeine; D019284:Thapsigargin; D002118:Calcium