Gi is involved in ethanol inhibition of L-type calcium channels in undifferentiated but not differentiated PC-12 cells
Mullikin-Kilpatrick, D.; Mehta, N.D.; Hildebrandt, J.D.; Treistman, S.N.
Molecular Pharmacology 47(5): 997-1005
1995
ISSN/ISBN: 0026-895X PMID: 7746286 Document Number: 449375
The effects of acute exposure to 25 mM ethanol on high voltage-activated, L-type Ca-2+ channels in undifferentiated and nerve growth factor-treated pheochromocytoma (PC-12) cells were examined using conventional, whole-cell, patch-clamp techniques. Acute exposure to 25 mM ethanol inhibited macroscopic L-type Ca-2+ currents in undifferentiated PC-12 cells significantly more than in nerve growth factor-treated PC-12 cells. Intracellular infusion with guanosine-5'-O-(2-thio)diphosphate or pretreatment with pertussis toxin reduced ethanol inhibition in undifferentiated cells without altering inhibition in nerve growth factor-treated cells, suggesting the involvement of a G protein in ethanol inhibition of Ca-2+ channels in undifferentiated cells. Intracellular infusion with an affinity-purified antibody that recognizes the carboxyl termini of alpha-i1 and alpha-i2 significantly reduced ethanol inhibition in undifferentiated cells, in contrast to the effects of antibodies that recognize the carboxyl termini of alpha-oA and alpha-oB. None of these antibodies reduced ethanol inhibition in nerve growth factor-treated cells. These results indicate that G-i1alpha or G-i2alpha mediates ethanol inhibition of L-type Ca-2+ channel currents in undifferentiated but not in nerve growth factor-treated PC-12 cells.