The role of ecto-ATPase in modulating the purinergic component of neur
otransmission in the guinea-pig vas deferens has been investigated usi
ng ARL 67156, a recently developed inhibitor of ecto-ATPase. ARL 67156
rapidly and reversibly potentiated neurogenic contractions in a conce
ntration-dependent manner ARL 67156 also potentiated contractions evok
ed by exogenous ATP, but had no effect on those to the stable analogue
alpha,beta-methyleneATP or on those to noradrenaline and KCl in the p
resence of the P-2-purinoceptor antagonist PPADS. These results are co
nsistent with an inhibitory action of ARL 67156 on ecto-ATPase and sug
gest that ecto-ATPase modulates purinergic neurotransmission in the gu
inea-pig vas deferens. (C) 1996 Academic Press Ltd