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- Balogh, Johanna, et al.
(författare)
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Phospholipase C and cAMP-dependent positive inotropic effects of ATP in mouse cardiomyocytes via P2Y(11)-like receptors.
- 2005
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Ingår i: Journal of Molecular and Cellular Cardiology. - : Elsevier BV. - 1095-8584 .- 0022-2828. ; 39:2, s. 223-230
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Tidskriftsartikel (refereegranskat)abstract
- ATP is released as a cotransmitter together with catecholamines from sympathetic nerves. In the heart ATP has been shown to cause a pronounced positive inotropic effect and may also act in synergy with β-adrenergic agonists to augment cardiomyocyte contractility. The aim of the present study was to investigate the inotropic effects mediated by purinergic P2 receptors using isolated mouse cardiomyocytes. Stable adenine nucleotide analogs were used and the agonist rank order for adenine nucleotide stimulation of the mouse cardiomyocytes was AR-C67085 > ATPγS > 2-MeSATP >>> 2-MeSADP = 0, that fits the agonist profile of the P2Y11 receptor. ATPγS induced a positive inotropic response in single mouse cardiomyocytes. The response was similar to that for the β1 receptor agonist isoproterenol. The most potent response was obtained using AR-C67085, a P2Y11 receptor agonist. This agonist also potentiated contractions in isolated trabecular preparations. The adenylyl cyclase blocker (SQ22563) and phospholipase C (PLC) blocker (U73122) demonstrated that both pathways were required for the inotropic response of AR-C67085. A cAMP enzyme immunoassay confirmed that AR-C67085 increased cAMP in the cardiomyocytes. These findings are in agreement with the P2Y11 receptor, coupled both to activation of IP3 and cAMP, being a major receptor for ATP induced inotropy. Analyzing cardiomyocytes from desmin deficient mice, Des–/–, with a congenital cardiomyopathy, we found a lower sensitivity to AR-C67085, suggesting a down-regulation of P2Y11 receptor function in heart failure. The prominent action of the P2Y11 receptor in controling cardiomyocyte contractility and possible alterations in its function during cardiomyopathy may suggest this receptor as a potential therapeutic target. It is possible that agonists for the P2Y11 receptor could be used to improve cardiac output in patients with circulatory shock and that P2Y11 receptor antagonist could be beneficial in patients with congestive heart failure (CHF).
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| 2. |
- Wihlborg, Anna-Karin, et al.
(författare)
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Positive inotropic effects by uridine triphosphate (UTP) and uridine diphosphate (UDP) via P2Y(2) and P2Y(6) receptors on cardiomyocytes and release of UTP in man during myocardial infarction
- 2006
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Ingår i: Circulation Research. - 0009-7330. ; 98:7, s. 970-976
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine a possible role for extracellular pyrimidines as inotropic factors for the heart. First, nucleotide plasma levels were measured to evaluate whether UTP is released in patients with coronary heart disease. Then, inotropic effects of pyrimidines were examined in isolated mouse cardiomyocytes. Finally, expression of pyrimidine-selective receptors ( a subgroup of the P2 receptors) was studied in human and mouse heart, using real time polymerase chain reaction, Western blot, and immunohistochemistry. Venous plasma levels of UTP were increased (57%) in patients with myocardial infarction. In electrically stimulated cardiomyocytes the stable P2Y(2/4) agonist UTP gamma S increased contraction by 52%, similar to beta(1)-adrenergic stimulation with isoproterenol (65%). The P2Y(6)-agonist UDP gamma S also increased cardiomyocyte contraction (35%), an effect abolished by the P2Y(6)-blocker MRS2578. The phospholipase C inhibitor U73122 inhibited both the UDP beta S and the UTP gamma S-induced inotropic effect, indicating an IP3-mediated effect via P2Y(6) receptors. The P2Y(14) agonist UDP-glucose was without effect. Quantification of mRNA with real time polymerase chain reaction revealed P2Y(2) as the most abundant pyrimidine receptor expressed in cardiomyocytes from man. Presence of P2Y(6) receptor mRNA was detected in both species and confirmed at protein level with Western blot and immunohistochemistry in man. In conclusion, UTP levels are increased in humans during myocardial infarction, giving the first evidence for UTP release in man. UTP is a cardiac inotropic factor most likely by activation of P2Y(2) receptors in man. For the first time we demonstrate inotropic effects of UDP, mediated by P2Y(6) receptors via an IP3-dependent pathway. Thus, the extracellular pyrimidines ( UTP and UDP) could be important inotropic factors involved in the development of cardiac disease.
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