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- Title
Mechanisms of spontaneous cytosolic Ca[sup 2+] transients in differentiated human neuronal cells.
- Authors
Gao, Zhi‐yong; Chen, Meng; Collins, Heather W.; Matschinsky, Franz M.; Lee, Virginia M. ‐Y.; Wolf, Bryan A.
- Abstract
We have studied Ca[sup 2+] homeostasis in a unique model of human neurons, the NT2N cell, which differentiates from a human teratocarcinoma cell line, NTera2/C1.D1 by retinoic acid treatment. When perifused with Krebs–HEPES buffer containing 2.5 mm CaCl[sub 2], fura-2 loaded NT2N cells produced spontaneous cytosolic Ca[sup 2+] oscillations, or Ca[sup 2+] transients. These cytosolic Ca[sup 2+] transients were not blocked by antagonists of glutamate (6-cyano-7-nitroquinoxaline-2,3-dione and d(–)-2-amino-5-phosphonopentanoic acid) or muscarinic (atropine) receptors. Omission of extracellular Ca[sup 2+] completely abolished Ca[sup 2+] oscillations and decreased the average Ca[sup 2+] level from 106 ± 14 nm to 59 ± 8 nm. Addition of the L-type Ca[sup 2+] channel blocker nifedipine (1 or 10 μm) or of the N-type inhibitor ω-conotoxin GVIA (5 μm) significantly, although incompletely, suppressed Ca[sup 2+] oscillations, while ω-conotoxin MVIIC (5 μm), a selective antagonist of P- and Q-channels, had no effect. Ni[sup 2+], at 100 μm, a concentration selective for T-type channels, did not inhibit Ca[sup 2+] transients. Non-specific blockage of Ca[sup 2+] channels by higher concentrations of Ni[sup 2+] (2–5 mm) or Co[sup 2+] (1 mm) abolished Ca[sup 2+] oscillations completely. The endoplasmic reticulum Ca[sup 2+]-ATPase inhibitor, thapsigargin (1 μm), slightly decreased Ca[sup 2+] oscillation frequency, and induced a small transitory increase in the average cytosolic Ca[sup 2+] concentration. The mRNAs of L- (α[sub 1D] subunit) and N-type (α[sub 1B] subunit) Ca[sup 2+] channel were present in NT2N cells, while that of a T-type Ca[sup 2+] channel (α[sub 1]-subunit) was not present in the NT2N cells as shown by reverse transcription–polymerase chain reaction. In conclusion, NT2N neuronal cells generate cytosolic Ca[sup 2+] oscillations mainly by influx of extracellular Ca[s...
- Subjects
CALCIUM; NEURONS
- Publication
European Journal of Neuroscience, 1998, Vol 10, Issue 7
- ISSN
0953-816X
- Publication type
Article
- DOI
10.1046/j.1460-9568.1998.00252.x