Evidence for separate receptors for ATP and adenosine in the guinea-pig taenia coli.

Inhibitory actions of three pairs of congeneric ATP and adenosine analogues on the isolated guinea-pig taenia coli were compared with the actions of ATP and adenosine. 8-Bromoadenosine, and 9-beta-D-arabinofuranosyladenosine (ara-adenosine) were inactive; 2'-deoxyadenosine was a weak partial agonist. 8-Bromo-ATP, ara-ATP and 2'-deoxy-ATP behaved like ATP and elicited rapid relaxations of the taenia but were not potentiated by dipyridamole. The divergent effects of identical structural modifications to ATP and adenosine provide evidence for separate adenosine and ATP receptors in the taenia coli.