Dependence of an adenosine-activated potassium current on a GTP-binding protein in mammalian central neurons.

Laurence Trussell, M. B. Jackson

Research output: Contribution to journalArticle

188 Citations (Scopus)

Abstract

Neurons in hippocampal and striatal cell cultures respond to adenosine with an inhibitory potassium current. This response disappears during whole-cell patch-clamp recording in which the cell is filled with minimal saline. We have found that this loss of sensitivity to adenosine can be prevented by including 100 microM GTP in the patch electrode filling solution. GDP is less effective than GTP in supporting the adenosine response, while GMP has little, if any, effect. Treatments known to inhibit GTP-binding proteins (G-proteins) block the adenosine-activated potassium current: The adenosine response is inhibited by including poorly metabolized analogs of guanine nucleotides along with GTP in the recording electrode. Diphosphate and triphosphate analogs appear to achieve this effect through different mechanisms. The adenosine response is also blocked by incubating cultures in islet-activating protein (pertussis toxin), an inhibitor of a class of G-protein. Thus, our data implicate a G-protein in the activation of a potassium current by adenosine. Intracellular ATP can increase the effectiveness of GMP, GDP, or low concentrations of GTP, suggesting that even during internal dialysis, neurons can maintain GTP levels through phosphotransferase reactions. Intracellular ATP also appears to suppress an outward current that is different from the adenosine-activated current. Raising intracellular cAMP levels either with bath-applied forskolin or by including a cAMP analog in the recording electrode did not alter the adenosine response. These results indicate that a G-protein is involved in the coupling between the adenosine receptor and a potassium channel, and that this coupling is not mediated by cAMP.

Original languageEnglish (US)
Pages (from-to)3306-3316
Number of pages11
JournalJournal of Neuroscience
Volume7
Issue number10
StatePublished - Oct 1987
Externally publishedYes

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GTP-Binding Proteins
Adenosine
Potassium
Neurons
Guanosine Triphosphate
Electrodes
Pertussis Toxin
Adenosine Triphosphate
Corpus Striatum
Purinergic P1 Receptors
Guanine Nucleotides
Diphosphates
Potassium Channels
Colforsin
Baths
Dialysis
Phosphotransferases
Cell Culture Techniques

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Dependence of an adenosine-activated potassium current on a GTP-binding protein in mammalian central neurons. / Trussell, Laurence; Jackson, M. B.

In: Journal of Neuroscience, Vol. 7, No. 10, 10.1987, p. 3306-3316.

Research output: Contribution to journalArticle

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