| 1. |
- Kim, HS, et al.
(författare)
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Methanocarba modification of uracil and adenine nucleotides: High potency of northern ring conformation at P2Y(1), P2Y(2), P2Y(4), and P2Y(11) but not P2Y(6) receptors
- 2002
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Ingår i: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 1520-4804 .- 0022-2623. ; 45:1, s. 208-218
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Tidskriftsartikel (refereegranskat)abstract
- The potency of nucleotide antagonists at P2Y(1) receptors was enhanced by replacing the ribose moiety with a constrained carbocyclic ring (Nandanan, et al. J. Med. Chem. 2000, 43, 829842). We have now synthesized ring-constrained methanocarba analogues (in which a fused cyclopropane moiety constrains the pseudosugar ring) of adenine and uracil nucleotides, the endogenous activators of P2Y receptors. Methanocarba-adenosine 5'-triphosphate (ATP) was fixed in either a Northern (N) or a Southern (S) conformation, as defined in the pseudorotational cycle. (N)-Methanocarba-uridine was prepared from the 1-amino-pseudosugar ring by treatment with beta-ethoxyacryloyl cyanate and cyclization to form the uracil ring. Phosphorylation was carried out at the 5'-hydroxyl group through a multistep process: Reaction with phosphoramidite followed by oxidation provided the 5'-monophosphates, which then were treated with 1,1'-carbonyldiimidazole for condensation with additional phosphate groups, The ability of the analogues to stimulate phospholipase C through activation of turkey P2Y(1) or human P2Y(1), P2Y(2), P2Y(4), P2Y(6), and P2Y(11) receptors stably expressed in astrocytoma cells was measured. At recombinant human P2Y(1) and P2Y(2) receptors, (N)-methanocarba-ATP was 138- and 41-fold, respectively, more potent than racemic (S)-methanocarba-ATP as an agonist. (N)methanocarba-ATP activated P2Y(11) receptors with a potency similar to ATP. (N)-Methanocarba-uridine 5'-triphosphate (UTP) was equipotent to UTP as an agonist at human P2Y2 receptors and also activated P2Y(4) receptors with an EC50 of 85 nM. (N)-Methanocarba-uridine 5'-diphosphate (UDP) was inactive at the hP2Y(6) receptor. The vascular effects of (N)-methanocarba-UTP and (N)-methanocarba-UDP were studied in a model of the rat mesenteric artery, The triphosphate was more potent than UTP in inducing a dilatory P2Y(4) response (pEC(50) = 6.1 +/- 0.2), while the diphosphate was inactive as either an agonist or antagonist in a P2Y(6) receptor-mediated contractile response. Our results suggest that new nucleotide agonists may be designed on the basis of the (N) conformation that favors selectivity for P2Y(1), P2Y(2), P2Y(4), and P2Y(11) receptors.
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| 2. |
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| 3. |
- Wihlborg, Anna-Karin, et al.
(författare)
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2,2 '-nitrophenylisatogen potentiates P2X(1) receptor mediated vascular contraction and blood pressure elevation
- 2003
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Ingår i: Drug Development Research (Proceedings of the Seventh International Symposium on Adenosine and Adenine Nucleotides - Part 2). - : Wiley. - 1098-2299 .- 0272-4391. ; 59:1, s. 82-87
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Konferensbidrag (refereegranskat)abstract
- The objective of this research was to examine the effects of chemical compounds with possible P2 receptor modulating effects and to characterize the potentiating effects of 2,2'-nitrophenylisatogen (NPI) on P2X(1) receptors in vitro and in vivo. Chemical compounds were tested in an in vitro pharmacological assay using vascular segments from the rat mesenteric artery stimulated by P2 receptor-specific agonists. Contractions were expressed as a percentage of 60 mM K+-induced contractions. Blood pressure was evaluated in pithed rats. NPI (30 muM) added 15 min before addition of the P2X(1) receptor-specific agonist alphabeta-MeATP increased the maximum vasoconstriction from 23% to 49% (an increase of 113%). Furthermore, NPI prevented the desensitization of repeated UP-MeATP contractions. Related compounds were examined, and 2-(3-methoxy-phenyl)-1-oxy-indol-3-one (MPI) had similar effects as NPI, but several others lacked effect. NPI had no effect on ADPbetaS (P2Y(1)) or acetylcholine-mediated vasodilatation, nor on UTP (P2Y(2/4)), UDP (P2Y(6)), or noradrenaline-mediated contractions. In pithed rats, the blood pressure response to 50 nmol/kg-infusion of alphabeta-MeATP was increased from 50+/-6 to 63+/-5 mmHg (P < 0.05), but had no effect on basal blood pressure or on the cardiovascular response to preganglionic nerve stimulation. In conclusion, NPI and MPI potentiates P2X(1) receptor vascular contractions in vitro and (NPI) blood pressure effects in vivo. It is possible that the effect is mediated by an inhibition of P2X(1) receptor desensitization. Drug Dev. Res. (C) Wiley-Liss, Inc.
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| 4. |
- Wihlborg, Anna-Karin, et al.
(författare)
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ADP Receptor P2Y12 Is Expressed in Vascular Smooth Muscle Cells and Stimulates Contraction in Human Blood Vessels.
- 2004
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1524-4636. ; 24:10, s. 1810-1815
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Tidskriftsartikel (refereegranskat)abstract
- Objective - ADP plays an important role in platelet aggregation by activating P2Y(12) receptors. We assessed the hypothesis that P2Y(12) receptors are expressed in vascular smooth muscle cells (VSMC). Methods and Results - P2Y(12) receptor mRNA was found to have a high expression among the P2 receptors in human VSMC, significantly higher than the other 2 ADP receptors (P2Y(1) and P2Y(13), real-time polymerase chain reaction). Western blots gave a band of 50 kD, similar to that in platelets. To unmask a P2Y(12) receptor-mediated vasoconstriction by simulating the in vivo situation, vessels were precontracted to a submaximal level. 2-MeSADP stimulated contractions in vessel segments from internal mammary artery (IM), IM branches and small veins (E-max = 15 +/- 6% of 60 mmol/L K+ contraction, pEC(50) = 5.6 +/- 0.6, E-max = 21 +/- 1%, pEC(50) = 6.8 +/- 0.1, and E-max = 48 +/- 9%, pEC(50) = 6.6 +/- 0.4). The selective P2Y(12) antagonist AR-C67085 blocked 2-MeSADP contractions. The contraction was not reduced in patients using clopidogrel, a drug inhibiting ADP-induced platelet aggregation by blocking the P2Y(12) receptor. This may be explained by the high instability of the active clopidogrel metabolite that never reaches the systemic circulation. Conclusion - ADP acting on P2Y(12) receptors not only is important for platelet activation but also stimulates vasoconstriction. Stable drugs with antagonistic effects on P2Y(12) receptors, affecting both platelets and VSMC, could be of double therapeutic benefit in their prevention of both thrombosis and vasospasm.
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| 5. |
- Wihlborg, Anna-Karin, et al.
(författare)
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Extracellular nucleotides induce vasodilatation in human arteries via prostaglandins, nitric oxide and endothelium-derived hyperpolarising factor.
- 2003
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Ingår i: British Journal of Pharmacology. - : Wiley. - 1476-5381 .- 0007-1188. ; 138:8, s. 1451-1458
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Tidskriftsartikel (refereegranskat)abstract
- 1. The present study was aimed at examining P2 receptor-mediated vasodilatation in human vessels. The isometric tension was recorded in isolated segments of the human left internal mammary artery branches precontracted with 1 muM noradrenaline. 2. Endothelial denudation abolished the dilator responses. 3. The selective P2Y1 agonist, 2-MeSADP, induced a potent vasodilatation (pEC50=6.9plusminus0.1). The P2Y1 antagonist of 10 muM, MRS 2216, shifted the 2-MeSADP concentration-response curve 1.1 log units to the right. The combined P2Y1 and P2X agonist, 2-MeSATP, stimulated a dilatation with a potency similar to that of 2-MeSADP. Furthermore, MRS 2216 had a similar antagonistic effect on both 2-MeSATP and 2-MeSADP indicating that P2X receptors do not mediate vasodilatation. 4. Both the P2Y2/4 agonist, UTPitalic gammaS and the P2Y6 agonist, UDPbetaS, stimulated potent dilatations (pEC50=7.8plusminus0.4 for UTPitalic gammaS and 8.4plusminus0.2 for UDPbetaS). 5. The 2-MeSADP-induced nitric oxide (NO)-mediated dilatation was studied in the presence of 10 muM indomethacin, 50 nM charybdotoxin and 1 muM apamin. The involvement of the endothelium-derived hyperpolarising factor (EDHF) was investigated in the presence of 0.1 mML-NOARG and indomethacin. The involvement of prostaglandins was investigated in the presence of L-NOARG, charybdotoxin and apamin. Both NO, EDHF and prostaglandins mediated 2-MeSADP dilatation with similar efficacy (Emax=25plusminus5% for NO, 25plusminus6% for EDHF and 27plusminus5% for prostaglandins). 6. In conclusion, extracellular nucleotides induce endothelium-derived vasodilatation in human vessels by stimulating P2Y1, P2Y2/4 and P2Y6 receptors, while P2X receptors are not involved. Endothelial P2Y receptors mediate dilatation by release of EDHF, NO and prostaglandins
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| 6. |
- Wihlborg, Anna-Karin
(författare)
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Novel functions of cardiovascular P2 receptors
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the thesis was to examine the expression and function of the extracellular nucleotide P2 receptors in the cardiovascular system. In the cardiovascular system nucleotides are released during shear stress, hypoxia, ischemia, from endothelial cells, smooth muscle cells, aggregating platelets, inflammatory cells and erythrocytes. We demonstrate that ATP, ADP, UTP and UDP induce vascular relaxation in human blood vessels stimulating P2Y1, P2Y2 and P2Y6 receptors on endothelial cells. ADP, acting on the P2Y1 receptor was the most potent vasodilator and the response was mediated via equal amounts of NO, EDHF and prostaglandins. We show that ADP gives contraction in human blood vessels and reveal functional expression of P2Y12 receptors on the VSMC. In vessels having an intact endothelium, ADP induces vasodilatation but a dysfunctional endothelium leads to ADP induced contraction. Stable drugs with antagonistic effects on P2Y12 receptors, affecting both platelets and VSMC, could be of double therapeutic benefit in their prevention of both thrombosis and vasospasm. Increased ATP release has been shown during cardiac ischemia. We found increased levels of UTP in patients with myocardial infarction and the amounts correlated to the ATP level (1:10). ATP, UTP and UDP stimulated potent inotropic effects acting on the heart muscle cells. The pyrimidine effects were mediated via P2Y2/4 and P2Y6 receptors acting via PLC pathways. Expression of P2Y2, P2Y4 and P2Y6 was verified using real-time PCR. ATP induced inotropic effects mediated via two pathways, PLC and adenylyl cyclase pathway, suggesting a P2Y11-like receptor in mouse. Responses to UDP and a P2Y11 agonist were decreased in mice with cardiomyopathy. Antagonists for P2Y2/4, P2Y6 and P2Y11 receptors could be beneficial in the treatment of hypertension and heart failure. Finally, by designing and synthesizing new chemical compounds, two new P2X1 receptor potentiating substances were found. The clinical use of a P2X1 receptor potentiator could be to increase blood pressure in orthostatic hypotension, counteract urinary incontinence, or even male infertility.
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