Pertussis toxin-sensitive G proteins mediate the inhibition of basal phosphoinositide metabolism caused by adenosine A1 receptors in rat hippocampal slices.
The adenosine A1 receptor selective agonist, N6-cyclopentyladenosine (CPA, 300 nM) inhibited basal accumulation of [3H]inositol phosphates ([3H]InsPs), but not the total levels of membrane [3H]-phosphoinositides, in rat hippocampal slices. This action of CPA was not significantly modified when synaptic transmission was blocked with tetrodotoxin (TTX, 200 nM) but was prevented in slices pre-incubated with pertussis toxin (PTX, 5 microg/mL) for 12-16 hr. Neither PTX nor TTX, when applied in the absence of CPA, influenced basal [3H]InsPs accumulation. It is concluded that the inhibition of the basal phosphatidylinositol metabolism by adenosine A1 receptor activation is independent of neurotransmission and involves a PTX-sensitive G protein, probably of the Gi/Go family.
Cascalheira
José F
JF
Laboratory of Biochemistry, Department of Chemistry, University Beira Interior, 6200 Covilhã, Portugal.
Sebastião
Ana M
AM
Ribeiro
J Alexandre
JA
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D066298:In Vitro Techniques; D037342:Pertussis Toxin / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000378:metabolism*; D058906:Purinergic P1 Receptor Agonists; D051381:Rats; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects; D013779:Tetrodotoxin / Q000494:pharmacology
D010716:Phosphatidylinositols; D058906:Purinergic P1 Receptor Agonists; D018047:Receptors, Purinergic P1; C048599:N(6)-cyclopentyladenosine; D013779:Tetrodotoxin; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D000241:Adenosine