Accumulations of inositol phosphates and cyclic AMP in brain slices: Synergistic interactions of histamine and 2-chloroadenosine

Abstract 2-Chloroadenosine, 5′-N-ethylcarboxamidoadenosine, N 6 -cyclohexyladenosine and other adenosine analogs enhance histamine-elicited, but not norepinephrine- or carbamylcholine-elicited accumulations of inositol phosphates in [ 3 H]inositol-labeled guinea-pig cerebral cortical slices. The adenosine analogs alone have no effect on accumulations of inositol phosphates. The effect of 2-chloroadenosine is blocked by the adenosine receptor antagonists theophylline and 1,3-dialkyl-8-p-sulfophenylxanthines. The rank order of activity of the six adenosine analogs with respect to augmentation of histamine-elicited accumulation of inositol phosphates in guinea-pig cerebral cortical slices is different from the rank order at an A 2 -adenosine receptor that mediates synergistic accumulations of cyclic AMP by adenosine analogs and histamine in guinea-pig cerebral cortical slices.