Journal of Neuroscience, Vol 15, 135-143, Copyright © 1995 by Society for Neuroscience
Facilitatory coupling between a glutamate metabotropic receptor and dihydropyridine-sensitive calcium channels in cultured cerebellar granule cells
P Chavis, JM Nooney, J Bockaert, L Fagni, A Feltz and JL Bossu
C.C.I.P.E., CNRS/INSERM, Montpellier, France.
The effect of metabotropic glutamate receptor activation on Ca
dihydropyridine (DHP)-sensitive channels recorded in the presence of 1
microM Bay K 8644 was examined on cultured cerebellar granule cells using
the patch-clamp technique in the cell-attached configuration. Bath-applied
agonist (trans-ACPD, 1S,3R-, and 1R,3S-ACPD isomers, and glutamate or
quisqualate in the presence of CPP and CNQX) evoked an increase in Ca
channel activity with a variable latency of 8.9 +/- 8.6 sec in 40% of the
recorded cells. Neither L-CCG1, L-AP3, L-AP4, nor AMPA or NMDA activated Ca
channels. Two dihydropyridine-sensitive channels present in this cell type
were activated by trans-ACPD: the classical 24 pS L-type channel and a
smaller-conductance 7 pS channel. The effect was shown to be mediated by
neither intracellular Ca2+ nor a pertussis toxin (PTX)-sensitive G protein.
Interestingly treatment with BAPTA-AM increased the number of responding
patches and the activity was more sustained throughout the drug
application. After overnight PTX treatment, activation of the Ca channels
persisted even after washout of the agonist. These results indicate that
mGluR1/mGluR5 probably mediate the facilitation of
dihydropyridine-sensitive Ca channels.
Previous Article | Next Article
