PACPX--a substituted xanthine--antagonizes both the A1 and A2 subclasses of the P1-purinoceptor: antagonism of the A2 subclass is competitive but antagonism of the A1 subclass is not

PACPX--a substituted xanthine--antagonizes both the A1 and A2 subclasses of the P1-purinoceptor: antagonism of the A2 subclass is competitive but antagonism of the A1 subclass is not