The dextro and levorotatory isomers of N-phenylisopropyladenosine: stereospecific effects on cyclic AMP-formation and evoked synaptic responses in brain slices

Smellie, F.W.; Daly, J.W.; Dunwiddie, T.V.; Hoffer, B.J.

Life Sciences 25(20): 1739-1748

1979


ISSN/ISBN: 0024-3205
PMID: 231163
DOI: 10.1016/0024-3205(79)90477-6
Accession: 068524927

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Abstract
The stereoisomers of N6-phenylisopropyladenosine elicit accumulations of cyclic Amp in brain slices via interaction with adenosine-receptors. The response in guinea pig cerebral cortical slices and in rat hippocampal slices is blocked by theophylline and potentiated by biogenic amines. A chelator, EGTA, potentiates the response to phenylisopropyladenosine in guinea pig cerebral cortical slices. The 1-isomer (EC50 25 μM) is four- to five-fold more potent than the d-isomer in eliciting accumulations of cyclic Amp in brain slices. In a rat coronal hippocampal slice in vitro, 1-phenylisopropyladenosine (IC50 ∼ 0.7 μM) reduces the amplitude of evoked synaptic responses generated via a monosynaptic pathway to the CA1 pyramidal neurons. The d-isomer is nearly one hundred-fold less potent. Thus, the adenosine-receptors involved in the electrophysical response appear much more stereoselective for the 1-isomer of phenylisopropyladenosine than the adenosine-receptors involved in cyclic AMP-generation in brain slices.