A monoclonal anti-idiotypic 'internal image' antibody that recognizes the A1 adenosine receptor potentiates the alpha 1-adrenergic activation of phospholipase C in primary cultures of mouse striatal astrocytes.

To determine which subtype of adenosine receptor mediates the potentiating effect of 2-chloroadenosine on the noradrenaline-induced inositol-phosphate formation, we used the monoclonal anti-idiotypic antibody AA1 that acts as an 'internal image' of adenosine and specifically recognizes the A1 adenosine receptor. In cultured mouse striatal astrocytes, AA1 increased the noradrenaline-evoked inositol phosphate (IP) accumulation, thus demonstrating a biological activity of an anti-idiotypic antibody. This effect was inhibited by PACPX, a selective A1 antagonist. Inhibitors of phospholipase A2 activity prevented the potentiation. These results establish the involvement of A1 adenosine receptors in the modulation of phospholipase C activity.