Recombinant GABA(B) receptors formed from GABA(B1) and GABA(B2) subunits selectively inhibit N-type Ca(2+) channels in NG108-15 cells.
Efficient transfection of NG108-15 cells with GABA(B) receptor subunits was achieved using polyethylenimine. Baclofen modulated high voltage-activated Ca(2+) current in differentiated cells transfected with GABA(B1) and GABA(B2) receptor subunits or with the GABA(B2) subunit alone, but not with the GABA(B1) subunit alone. Characteristics of the current modulation were very similar for cells transfected with GABA(B1/2) and GABA(B2) subunits. Using antisense oligonucleotides against GABA(B1) subunits and also western immunoblotting, we are able to show that NG108-15 cells contain endogenous GABA(B1) subunits. Therefore, functional receptors can be formed by the combination of native GABA(B1) subunits with transfected GABA(B2) subunits, in agreement with the proposed heteromeric structure of GABA(B) receptors. Finally, we used selective channel blockers to identify the subtypes of Ca(2+) channels that are modulated by GABA(B) receptors. In fact, in differentiated NG108-15 cells, the recombinant GABA(B) receptors couple only to N-type Ca(2+) channels.
Easter
Alison
A
Division of Neuroscience-Pharmacology, Medical School, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Spruce
Austen E
AE
D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D020747:Calcium Channels, T-Type / Q000502:physiology*; D016373:DNA, Antisense / Q000494:pharmacology; D004274:DNA, Recombinant / Q000502:physiology; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009543:Nifedipine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010721:Phosphinic Acids / Q000494:pharmacology; D010957:Plasmids / Q000235:genetics; D011412:Propanolamines / Q000494:pharmacology; D021122:Protein Subunits; D018080:Receptors, GABA-B / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured; D020866:omega-Conotoxin GVIA / Q000494:pharmacology
D020747:Calcium Channels, T-Type; D016373:DNA, Antisense; D004274:DNA, Recombinant; D018755:GABA Agonists; D018756:GABA Antagonists; D010721:Phosphinic Acids; D011412:Propanolamines; D021122:Protein Subunits; D018080:Receptors, GABA-B; C085075:CGP 55845A; D020866:omega-Conotoxin GVIA; D001418:Baclofen; D009543:Nifedipine; D009638:Norepinephrine