Dopamine and 5-hydroxytryptamine selectively potentiate neuronal type ATP receptor channels

Dopamine and 5-hydroxytryptamine have been shown to facilitate a cationic current activated by extracellular ATP in rat pheochromocytoma PC12 cells. Effects of these and other modulators were examined by expressing ATP receptor channels in Xenopus oocytes using cDNAs from rat vas deferens ('P2x1-purinoceptor channels') and PC12 cells ('P2x2-purinoceptor channels'). Dopamine and 5-hydroxytryptamine (10 and 100 mu M) facilitated the ATP-activated current mediated through P2x2-purinoceptor channels, but not the current through P2x1-purinoceptor channels. Adenosine (1 mu M) facilitated the current through both P2x1- and P2x2-purinoceptor channels. Cd2+ (1 mM) as well as Zn2+ (10 mu M) selectively potentiated the current through P2x2-purinoceptor channels. The results suggest that (1) the facilitation by dopamine and other modulators also occurs in recombinant ATP-receptor channels, and (2) the selective facilitation by dopamine, 5-hydroxytryptamine and divalent cations of P2x2-purinoceptor channels is attributed to some structural difference of the channels from P2x1-purinoceptor channels.