Reactive blue 2 discriminates between responses mediated by UTP and those evoked by ATP or alpha,beta-methylene-ATP on rat sympathetic ganglia.

The effect of reactive blue 2, a P2 purinoceptor antagonist on depolarisation of the rat superior cervical ganglion evoked by ATP, alpha,beta-methylene-ATP (alpha,beta-Me-ATP) and uridine 5'-triphosphate (UTP) was determined. UTP, alpha,beta-Me-ATP and ATP (in the presence of an A1 purinoceptor antagonist) produced a depolarisation in that order of potency. Reactive blue 2 (30 microM) antagonised alpha,beta-Me-ATP-evoked depolarisations without altering responses evoked by adenosine or UTP. Reactive blue (100 or 300 microM) enhanced UTP- and depressed alpha,beta-Me-ATP- or ATP- (at 100 microM reactive blue 2) evoked depolarisations. These results indicate that rat superior cervical ganglia possess purinoceptors and pyrimidinoceptors.