PT  - JOURNAL ARTICLE
AU  - G L Kamatchi
AU  - M K Ticku
TI  - A functional assay to measure postsynaptic gamma-aminobutyric acidB responses in cultured spinal cord neurons: heterologous regulation of the same K+ channel.
DP  - 1991 Feb 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 426--431
VI  - 256
IP  - 2
4099  - http://jpet.aspetjournals.org/content/256/2/426.short
4100  - http://jpet.aspetjournals.org/content/256/2/426.full
SO  - J Pharmacol Exp Ther1991 Feb 01; 256
AB  - The stimulation of postsynaptic gamma-aminobutyric acid (GABA)B receptors leads to slow inhibitory postsynaptic potentials due to the influx of K(+)-ions. This was studied biochemically, in vitro in mammalian cultured spinal cord neurons by using 86Rb as a substitute for K+. (-)-Baclofen, a GABAB receptor agonist, produced a concentration-dependent increase in the 86Rb-influx. This effect was stereospecific and blocked by GABAB receptor antagonists like CGP 35 348 (3-aminopropyl-diethoxymethyl-phosphonic acid) and phaclofen. Apart from the GABAB receptors, both adenosine via adenosine1 receptors and 5-hydroxytryptamine (5-HT) via 5-HT1 alpha agonists also increased the 86Rb-influx. These agonists failed to show any additivity between them when they were combined in their maximal concentration. In addition, their effect was antagonized specifically by their respective antagonists without influencing the others. These findings suggest the presence of GABAB, adenosine1 and 5-HT1 alpha receptors in the cultured spinal cord neurons, which exhibit a heterologous regulation of the same K(+)-channel. The effect of these agonists were antagonized by phorbol 12,13-didecanoate, an activator of protein kinase C, and pretreatment with pertussis toxin. This suggests that these agonists by acting on their own receptors converge on the same K(+)-channel through the Gi/Go proteins. In summary, we have developed a biochemical functional assay for studying and characterizing GABAB synaptic pharmacology in vitro, using spinal cord neurons.