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

Abstract

1 Using a grease-gap recording technique we have investigated the effects of some antagonists of P2-purinoceptors on the depolarization of the rat isolated superior cervical ganglion evoked by 100 gM a,,fmethylene-adenosine 5'-triphosphate (ac,,B-MeATP) or uridine 5'-triphosphate (UTP). The effects of the putative P2z-purinoceptor antagonist, coomassie brilliant blue G, putative P2x-purinoceptor antagonist, 4,4'-diisothiocyanatostilbene-2,2'-disulphonate (DIDS) and uniblue A (an analogue of the P2Y-and P2X-purinoceptor antagonist reactive blue 2) were investigated.2 At the highest concentration examined uniblue A (300 gM) depressed a,#-MeATP-induced depolarization and at 100 and 300 gM enhanced UTP-evoked depolarizations. Coomassie brilliant blue G (1 and 10 gM) did not affect depolarizations evoked by a,#-MeATP or UTP. Depolarizations evoked by potassium (5 mM) or muscarine (100 nM) were unaltered by either coomassie brilliant blue G or uniblue A. Uniblue A (100 and 300 g1M) produced a concentration-dependent depression of hyperpolarizations evoked by adenosine (100 giM) whereas coomassie brilliant blue G at up to 10 UM, did not alter adenosine-induced hyperpolarizations. 3 DIDS (30 and 100 jiM) did not alter adenosine-evoked hyperpolarizations, or depolarizations evoked by potassium or UTP. DIDS at 100 gM did not alter depolarizations evoked by muscarine. In contrast DIDS produced a concentration-dependent depression of ax,fi-MeATP-evoked depolarizations.4 These results are consistent with the proposal that uniblue A and DIDS but not coomassie brilliant blue G are antagonists of P2-purinoceptors and that uniblue A is also an antagonist at P,-purinoceptors present on the rat superior cervical ganglion. 5 The ability of uniblue A and DIDS to distinguish between depolarizations evoked by UTP and a,flMeATP provides further justification for the proposal that these nucleotides activate separate receptors present on the rat superior cervical ganglion, i.e. pyrimidinoceptors and P2-purinoceptors respectively.

Mechanical strain-induced Ca2+waves are propagated via ATP release and purinergic receptor activation

“…An increase of ATP release in the presence of DIDS following hypotonic incubation has been recently reported (25) and has been interpreted as inhibition of ecto-ATPases, which rapidly degrade extracellular ATP. The inhibitory effects of DIDS on Ca i 2ϩ wave propagation therefore may be explained by its previously demonstrated effect as an antagonist of purinergic receptors (5,11,29).…”

Purine and Pyrimidine (P2) Receptors as Drug Targets

“…b. Anthraquinone Class. Reactive Blue 2, 27 , among the most widely used P2 receptor antagonists, is a mixture of m - and p -sulfonate isomers, while Cibachron Blue 3GA, 28 , is the corresponding pure o -isomer. , Compound 27 was reported as a competitive P2Y antagonist at the adenylate cyclase coupled P2Y receptors of C6 glioma cells with a K B value of 25 nM, which had at least a 50-fold higher affinity than those reported in other tissues . Compound 27 blocks P2X 1 -like receptors in rat vas deferens (IC 50 = 30.4 μM, K d = 11.4 μM) and P2Y 1 -like receptors in guinea pig taenia coli ( K d = 3.4 μM) .…”

“…Compound 27 blocks P2X 1 -like receptors in rat vas deferens (IC 50 = 30.4 μM, K d = 11.4 μM) and P2Y 1 -like receptors in guinea pig taenia coli ( K d = 3.4 μM) . Compound 28 is approximately 7-fold more potent than 27 at P2X 1 -like receptors in rat vas deferens (IC 50 = 9.6 μM, K d = 1.6 μM) but has similar potency at P2Y 1 -like receptors in guinea pig taenia coli ( K d = 2.9 μM) . Acid Blue 129, 29 , has modest antagonist activity at P2Y 1 -receptors in guinea pig taenia coli (IC 50 = 3.0 μM, K d = 1.4 μM) and shows greater than 71-fold selectivity versus P2X 1 -like receptors in rat vas deferens ( K d > 100 μM) .…”

“…261 Compound 28 is approximately 7-fold more potent than 27 at P2X 1 -like receptors in rat vas deferens (IC 50 ) 9.6 µM, K d ) 1.6 µM) but has similar potency at P2Y 1 -like receptors in guinea pig taenia coli (K d ) 2.9 µM). 259 Acid Blue 129, 29, has modest antagonist activity at P2Y 1 -receptors in guinea pig taenia coli (IC 50 ) 3.0 µM, K d ) 1.4 µM) and shows greater than 71-fold selectivity versus P2X 1 -like receptors in rat vas deferens (K d > 100 µM). 259 Uniblue A, 30, is a potent antagonist at P2X 1 -like receptors in rat vas deferens (IC 50 ) 7.5 µM, K d ) 0.8 µM) and shows greater than 125-fold selectivity versus P2Y 1 -like receptors in guinea pig taenia coli (K d > 100 µM).…”

Extracellular ATP Activates Calcium Signaling, Ion, and Fluid Transport in Retinal Pigment Epithelium

“…In the presence of cyclopiazonic acid, ATP did not elicit a measurable increase in TEP during phase I and decreased the TEP by 1.2 mV during phase II. Measurements were made in a different tissue from A. cervical ganglia, as well as in P 2X -receptors cloned from smooth muscles heterologously expressed in oocytes and human 293 cells (Bultmann and Starke, 1994;Connolly and Harrison, 1995;Evans et al, 1995). In the present study, we tested the ability of DIDS to block the ATP responses.…”