UTPγS trisodium salt

The stable pyrimidines UDPbetaS and UTPgammaS discriminate between contractile cerebrovascular P2 receptors.[Pubmed:12504787]

Eur J Pharmacol. 2003 Jan 5;458(3):305-11.

Extracellular nucleotides were used to characterise the contractile P2 receptors in the rat basilar artery. The isometric tension was recorded in vitro and receptor mRNA expression was examined by reverse transcriptase polymerase chain reaction (RT-PCR) after endothelium-denudation. Transient vasoconstriction was evoked by alphabeta-methylene-adenosine triphosphate (alphabeta-MeATP), indicating the presence of P2X(1) receptors. The P2Y receptors were analysed after P2X receptor desensitisation with 10 microM alphabeta-MeATP. Uridine diphosphate (UDP) and uridine triphosphate (UTP) induced sustained contractions of similar magnitude. The stable nucleotide analogue, uridine 5'-O-thiodiphosphate (UDPbetaS), was clearly more potent than uridine 5'-O-3-thiotriphosphate (UTPgammaS), suggesting prominent contractile effects of P2Y(6) receptors. P2Y(2) and P2Y(4) receptors might also be involved in nucleotide responses, since UTPgammaS and adenosine 5'-O-3-thiotriphosphate (ATPgammaS) were of similar potency. The P2Y(1) selective agonists, adenosine 5'-O-thiodiphosphate (ADPbetaS) and 2-methylthioadenosine diphosphate (2-MeSADP) did not induce contractions. RT-PCR analysis demonstrated P2X(1), P2Y(1), P2Y(2) and P2Y(6) receptor mRNA expression, while the P2Y(4) band was weak. In conclusion, extracellular nucleotides induce contractions of cerebral arteries primarily by activation of P2Y(6) receptors on smooth muscle cells, with a lesser contribution of P2Y(2) and P2X(1) receptors. Although mRNA for the P2Y(1) receptor was detected by RT-PCR, it does not mediate contraction.

The stable pyrimidines UDPbetaS and UTPgammaS discriminate between the P2 receptors that mediate vascular contraction and relaxation of the rat mesenteric artery.[Pubmed:10960068]

Br J Pharmacol. 2000 Sep;131(1):51-6.

The contractile and relaxant effects of the different P2 receptors were characterized in the rat isolated mesenteric artery by use of extracellular nucleotides, including the stable pyrimidines uridine 5'-O-thiodiphosphate (UDPbetaS) and uridine 5'-O-3-thiotriphosphate (UTPgammaS). The selective P2X receptor agonist, alphabeta-methylene-adenosine triphosphate (alphabeta-MeATP) stimulated a potent (pEC(50)=6.0) but relatively weak contraction (E:(max)=57% of 60 mM K(+)). The contractile concentration-response curve of adenosine triphosphate (ATP) was biphasic when added in single concentrations. The first part of the response could be desensitized by alphabeta-MeATP, indicating involvement of P2X receptors, while the second part might be mediated by P2Y receptors. The contractile P2Y receptors were further characterized after P2X receptor desensitization with 10 microM alphabeta-MeATP. Uridine diphosphate (UDP), uridine triphosphate (UTP) and ATP stimulated contraction only in high concentrations (1 - 10 mM). The selective P2Y(6) agonist, UDPbetaS, and the P2Y(2)/P2Y(4)-receptor agonists UTPgammaS and adenosine 5'-O-3-thiotriphosphate (ATPgammaS) were considerably more potent and efficacious (E:(max) approximately 250% of 60 mM K(+)). Adenosine 5'-O-thiodiphosphate (ADPbetaS) was inactive, excluding contractile P2Y(1) receptors. After precontraction with 1 microM noradrenaline, UTP, ADP and ATP induced relaxations with similar potencies (pEC(50) approximately 5.0). UTPgammaS, ADPbetaS and ATPgammaS were approximately one log unit more potent indicating the presence of endothelial P2Y(1) and P2Y(2)/P2Y(4) receptors. The P2Y(6) receptor agonist, UDPbetaS, had no effect. UDPbetaS and UTPgammaS are useful tools when studying P2 receptors in tissue preparations with ectonucleotidase activity. Contractile responses can be elicited by stimulation of P2Y(6) and, slightly less potently, P2Y(2)/P2Y(4) receptors. The P2X response was relatively weak, and there was no P2Y(1) response. Stimulation of P2Y(1) and P2Y(2)/P2Y(4) receptors elicited relaxation, while P2Y(6) did not contribute.

Enzymatic synthesis of UTP gamma S, a potent hydrolysis resistant agonist of P2U-purinoceptors.[Pubmed:8825364]

Br J Pharmacol. 1996 Jan;117(1):203-9.

1. The defective Cl- secretion characteristic of cystic fibrosis airway epithelial cells can be bypassed by an alternative Ca2+ dependent Cl- secretory pathway that is activated by extracellular nucleotides, e.g. uridine-5'triphosphate (UTP), acting on P2U purinoceptors. Since UTP is susceptible to hydrolysis by nucleotidases and phosphatases present in the airways, the identification of stable P2U-purinoceptor agonists would be of therapeutic relevance. 2. Uridine-5'-O-(3-thiotriphosphate) (UTP gamma S) was synthesized by nucleoside diphosphate kinase-catalyzed transfer of the gamma-phosphorothioate from guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S) or adenosine-5' = O-(3-thiotriphosphate) (ATP gamma S) to UDP. Formation of UTP gamma S was illustrated by observation of transfer of 35S from [35S]-GTP gamma S and transfer of 3H from [3H]-UDP. The chemical identity of high performance liquid chromatography (h.p.l.c.)-purified UTP gamma S was confirmed by nuclear magnetic resonance analysis. 3. Human 1321N1 astrocytoma cells stably expressing the phospholipase C-coupled human P2U-purinoceptor were utilized to test the activity of UTP gamma S. UTP gamma S (EC50 = 240 nM) was essentially equipotent to UTP and ATP for stimulation of inositol phosphate formation. 4. Unlike [3H]-UTP, [3H]-UTP gamma S was not hydrolyzed by alkaline phosphatase, acid phosphatase, or apyrase. Moreover, no hydrolysis was detected during a 1 h incubation with human nasal epithelial cells. 5. UTP gamma S was equally potent and efficacious with UTP for stimulation of Cl- secretion by human nasal epithelium from both normal donors and cystic fibrosis patients. Based on its high potency and resistance to hydrolysis, UTP gamma S represents a promising compound for treatment of cystic fibrosis.