The effect of calcium channel antagonists on the release of [3H]noradrenaline in the human neuroblastoma, SH-SY5Y (original) (raw)

1991, Neuroscience Letters

The effect of calcium channel antagonists on depolarization and carbachol evoked release of [3H]noradrenaline in the human neuroblastoma, SH-SY5Y, was investigated. Nifedipine, verapamil and diltiazem completely inhibited the depolarization evoked release of [3H]noradrenaline with IC50 values of 0.44 ___ 0.1 #M, 3.6 + 0.24 laM and 5.6 ___ 0.2/~M respectively. In addition, nickel, cobalt and cadmium, all at 2 mM, inhibited depolarization evoked release by 89.2 ___ 2.3%, 72.6 ___ 1.6% and 102.5 + 1.4% respectively. Furthermore, to-conotoxin resulted in at least 20% inhibition of potassium evoked release, suggesting a role of N-type calcium channels. Carbachol evoked release of [3H]noradrenaline was inhibited by l0-4 M nifedipine, diltiazem and verapamil by 15.6 + 1.1%, 14.6 ___ 3.2% and 23.6 + 1.8% respectively and by 2 mM nickel, cobalt and cadmium by 13.8 ___ 3.2%, 34 +2.1% and 6.5 + 3.7% respectively. These results suggest that depolarization evoked release of [3Hlnoradrenaline is mediated via Land N-type calcium channels, whereas, carbachol evoked release does not appear to be coupled an L-, T-or N-type voltage sensitive calcium channel.