Polarized effects of amiloride and 4,4′-diisothiocyano-stilbene-2,2′-disulfonic acid on ATP-induced contraction of trachea

Discrimination between UTP‐ and P2‐purinoceptor‐mediated depolarization of rat superior cervical ganglia by 4, 4′‐diisothiocyanatostilbene‐2, 2′‐disulphonate (DIDS) and uniblue A

“…Depolarizations evoked by potassium, muscarine and UTP were unaltered by DIDS, whereas depolarizations evoked by a,fl-MeATP (a selective P2X-purinoceptor agonist) were depressed in a conentration-dependent manner suggesting that DIDS is an antagonist of P2X-purinoceptors. This conclusion is consistent with the observations that DIDS antagonized ATPevoked contraction of the guinea-pig vas deferens (Fedan & Lamport, 1990) and more recently was shown to antagonize contractions of the rat vas deferens elicted by a,#-MeATP Starke, 1994) indicating that it is a P2x-purinoceptor antagonist.…”

“…a pyrimidinoceptor as has been proposed in earlier studies (Connolly et al, 1993b;Connolly, 1994a). Although the effects of DIDS on P2-purinoceptor subtypes other than at P2Z-and P2X-purinoceptors (Fedan et al, 1990;Soltoff et al, 1993;Bfiltmann & Starke, 1994), including the P2Y-purinoceptor have yet to be reported, it seems unlikely that the inability of DIDS to potentiate UTP-evoked depolarizations results from a lack of antagonism of an opposing P2Y-purinoceptor-mediated hyperpolarization. This assumption is based upon the observation that suramin and reactive blue 2 (two antagonists of P2X-and P2y-purinoceptors) and PPADS (a selective P2Xpurinoceptor antagonist) all produced an enhancement of UTP-and a corresponding depression of a,#-MeATP or ATPevoked depolarizations of the rat SCG (Connolly et al, 1993b;Connolly, 1994b;Connolly & Harrison, 1994a;Connolly, 1994c respectively).…”

“…Other compounds apart from suramin have been suggested to antagonize P2-purinceptors, e.g. 4,4'-diisothiocyanatostilbene-2,2'-disulphonate (DIDS) (Figure la) (Fedan & Lamport, 1990;Soltoffet al, 1993;Bultmann & Starke, 1994), coomassie brilliant blue G (Figure lb) (Soltolf et al, 1989;Inoue et al, 1991) and reactive blue 2 (Figure ic) (Burnstock, 1978;Burnstock & Kennedy, 1985) and thus we sought to examine the effect of some of these P2-purinoceptor antagonists on depolarizations of rat SCG elicited by a,,B-MeATP and UTP.…”