mrs-1191 and Myocardial-Infarction

Recent studies demonstrated that resveratrol, a grape-derived polyphenolic phytoalexin, provides pharmacological preconditioning (PC) of the heart through a NO-dependent mechanism. Because adenosine receptors play a role in PC, we examined whether they play any role in resveratrol PC. Rats were randomly assigned to groups perfused for 15 min with 1) Krebs-Henseleit bicarbonate buffer (KHB) only; 2) KHB containing 10 microM resveratrol; 3) 10 microM resveratrol + 1 microM 8-cyclopentyl-1,3-dimethylxanthine (CPT; adenosine A(1) receptor blocker); 4) 10 microM resveratrol + 1 microM 8-(3-chlorostyryl)caffeine (CSC; adenosine A(2a) receptor blocker); 5) 10 microM resveratrol + 1 microM 3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1,4-(+/-)-dihydropyridine-3,5-dicarboxylate (MRS-1191; adenosine A(3) receptor blocker); or 6) 10 microM resveratrol + 3 microM 2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride [LY-294002, phosphatidylinositol (PI)3-kinase inhibitor], and groups perfused with adenosine receptor blockers alone. Hearts were then subjected to 30-min ischemia followed by 2-h reperfusion. The results demonstrated significant cardioprotection with resveratrol evidenced by improved ventricular recovery and reduced infarct size and cardiomyocyte apoptosis. CPT and MRS 1191, but not CSC, abrogated the cardioprotective abilities of resveratrol, suggesting a role of adenosine A(1) and A(3) receptors in resveratrol PC. Resveratrol induced expression of Bcl-2 and caused its phosphorylation along with phosphorylation of cAMP response element-binding protein (CREB), Akt, and Bad. CPT blocked phosphorylation of Akt and Bad without affecting CREB, whereas MRS 1191 blocked phosphorylation of all compounds, including CREB. LY-294002 partially blocked the cardioprotective abilities of resveratrol. The results indicate that resveratrol preconditions the heart through activation of adenosine A(1) and A(3) receptors, the former transmitting a survival signal through PI3-kinase-Akt-Bcl-2 signaling pathway and the latter protecting the heart through a CREB-dependent Bcl-2 pathway in addition to an Akt-Bcl-2 pathway.

Topics: Adenosine A3 Receptor Antagonists; Animals; Apoptosis; bcl-Associated Death Protein; Carrier Proteins; Cyclic AMP Response Element-Binding Protein; Dihydropyridines; Heart; Male; Myocardial Infarction; Myocytes, Cardiac; Phosphorylation; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Purinergic P1 Receptor Antagonists; Rats; Rats, Sprague-Dawley; Receptor, Adenosine A3; Resveratrol; Signal Transduction; Stilbenes; Theophylline

A recent study documented a role of adenosine A(3)-Akt-cAMP response element-binding protein (CREB) survival signaling in resveratrol preconditioning of the heart. In this study, we demonstrate that resveratrol-mediated CREB activation can also occur through an Akt-independent pathway. Isolated rat hearts were perfused for 15 min with Krebs-Henseleit bicarbonate (KHB) buffer containing resveratrol in the absence or presence of adenosine A(3) receptor blocker MRS-1191 [3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1,4-(+/-)-dihydropyridine-3,5-dicar-boxylate], phosphatidylinositol 3 (PI3)-kinase inhibitor LY294002 [2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride], mitogen-activated extracellular signal-regulated protein kinase inhibitor PD098059 [2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one], or a combination of LY294002 and PD098059. All hearts were subsequently subjected to 30-min ischemia followed by 2-h reperfusion. Cardioprotection was examined by determining infarct size, cardiomyocyte apoptosis, and ventricular recovery. Resveratrol phosphorylated both Akt and CREB that was blocked by MRS-1191, which also abolished cardioprotective abilities of resveratrol. LY294002 completely inhibited Akt phosphorylation but partially blocked the phosphorylation of CREB. Inhibition of PI3-kinase also partially blocked resveratrol's ability to precondition the heart. PD098059 partially blocked the phosphorylation of CREB and resveratrol-mediated cardioprotection. Preperfusing the hearts with LY294002 and PD098059 together completely abolished the phosphorylation of CREB, simultaneously inhibiting resveratrol-mediated cardioprotection. The results indicate that resveratrol preconditions the hearts through adenosine A(3) receptor signaling that triggers the phosphorylation of CREB through both Akt-dependent and -independent pathways, leading to cardioprotection.

Topics: Adenosine A3 Receptor Antagonists; Animals; Apoptosis; Biotransformation; Blotting, Western; Cyclic AMP Response Element-Binding Protein; Dihydropyridines; Enzyme Inhibitors; Heart Function Tests; In Situ Nick-End Labeling; Male; Mitogen-Activated Protein Kinases; Myocardial Contraction; Myocardial Infarction; Myocytes, Cardiac; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Resveratrol; Stilbenes

We investigated the role of protein kinase C in adenosine A3 receptor (A3AR)-induced delayed cardioprotection in the mouse heart. Mice were treated with selective A3AR agonist N6-(3-iodobenzyl)adenosine-5'-N-methyluronamide (IB-MECA). Twenty-four hours later, hearts were perfused in the Langendorff mode and subjected to 30 min of global ischemia and 30 min of reperfusion. Infarct size was determined by computer morphometry of tetrazolium-stained sections, and ventricular function was monitored by inserting a fluid-filled balloon into the left ventricle (LV). Chelerythrine chloride (CHE, 5.0 mg/kg) and rottlerin (Rot, 0.3 mg/kg) were given 30 min before IB-MECA to block total and PKC-delta isoforms, respectively. IB-MECA caused postischemic reduction in necrosis and improvement in ventricular function, which was abolished by CHE. Western blot analysis demonstrated translocation of the PKC-delta isoform but not the alpha, epsilon, xi, eta isoform(s) from cytoplasm to the membrane fraction after 30 min of IB-MECA administration. A3AR antagonist MRS-1191 and CHE blocked the translocation of PKC-delta. Furthermore, IB-MECA-induced increase in nuclear factor-kappaB binding was diminished by CHE. These results provide direct evidence of an essential role of PKC, and more specifically, PKC-delta in A3AR-induced delayed cardioprotection.

Topics: Adenosine; Alkaloids; Animals; Benzophenanthridines; Blotting, Western; Cell Nucleus; Cytosol; Dihydropyridines; Electrophoretic Mobility Shift Assay; Enzyme Inhibitors; Heart Diseases; Heart Function Tests; In Vitro Techniques; Isoenzymes; Male; Mice; Myocardial Contraction; Myocardial Infarction; NF-kappa B; Phenanthridines; Protein Kinase C; Purinergic P1 Receptor Antagonists; Receptor, Adenosine A3; Receptors, Purinergic P1

Adenosine-enhanced ischemic preconditioning (APC) extends the cardioprotection of ischemic preconditioning (IPC) by both significantly decreasing myocardial infarct size and significantly enhancing postischemic functional recovery. In this study, the role of adenosine receptors during ischemia-reperfusion was determined. Rabbit hearts (n = 92) were used for Langendorff perfusion. Control hearts were perfused for 180 min, global ischemia hearts received 30-min ischemia and 120-min reperfusion, and IPC hearts received 5-min ischemia and 5-min reperfusion before ischemia. APC hearts received a bolus injection of adenosine coincident with IPC. Adenosine receptor (A(1), A(2), and A(3)) antagonists were used with APC before ischemia and/or during reperfusion. GR-69019X (A(1)/A(3)) and MRS-1191/MRS-1220 (A(3)) significantly increased infarct size in APC hearts when administered before ischemia and significantly decreased functional recovery when administered during both ischemia and reperfusion (P < 0.05 vs. APC). DPCPX (A(1)) administered either before ischemia and/or during reperfusion had no effect on APC cardioprotection. APC-enhanced infarct size reduction is modulated by adenosine receptors primarily during ischemia, whereas APC-enhanced postischemic functional recovery is modulated by adenosine receptors during both ischemia and reperfusion.

Topics: Adenosine; Animals; Dihydropyridines; In Vitro Techniques; Ischemic Preconditioning, Myocardial; Myocardial Infarction; Myocardial Reperfusion Injury; Purinergic P1 Receptor Agonists; Purinergic P1 Receptor Antagonists; Rabbits; Receptors, Purinergic P1; Ventricular Pressure; Xanthines

There is currently general agreement that adenosine is not involved in ischemic preconditioning (IP) in rat hearts. We hypothesized that the failure to show a role for adenosine is due to the use of brief preconditioning stimuli, and therefore investigated whether adenosine is involved when longer stimuli are employed and which receptor subtypes are involved.. Infarct size (IS) was determined in anesthetized rats after 180 min of reperfusion (REP) following a 60-min coronary artery occlusion (CAO). IS was 69+/-2% (n=15) of the risk area in control rats and 45+/-2% (n=19; P<0.05) following IP by a single 15-min CAO. The non-selective adenosine receptor antagonist SPT, which itself had no effect on IS (74+/-1%), blunted the protection by IP (IS=57+/-2%, P<0.05) in a dose of 2 x 5 mg/kg i.v., and abolished the protection (IS=70+/-1%) at 2 x 25 mg/kg i.v. Following IP by three cycles of 3-min CAO and 3-min REP, IS was 24+/-6% (P<0.05), which was not affected by SPT in doses of 2 x 10 and 2 x 25 mg/kg i.v. The A(3) antagonist MRS-1191 (3.3 mg/kg, i.p.), which itself did not affect IS (70+/-2%), blunted the protection by IP with a 15-min CAO (IS=54+/-2%, P<0.05). When 2 x 5 mg/kg SPT (a dose selective for A(1)-receptors, as it did not affect the protection by the A(3) selective agonist IB-MECA, 51+/-3%) and MRS 1191 were combined the protection by IP was abolished (IS=67+/-2%).. Involvement of adenosine in IP in rats depends critically on the duration of the stimulus. Thus, whereas adenosine was not involved when stimuli of 3-min duration were employed, activation of both A(1) and A(3) receptors contributed when a stimulus of 15 min was used.

Topics: Acetamides; Adenosine; Analysis of Variance; Animals; Cryoprotective Agents; Dihydropyridines; Histamine H1 Antagonists; Ischemic Preconditioning, Myocardial; Male; Myocardial Infarction; Purinergic Antagonists; Purinergic P1 Receptor Antagonists; Pyrilamine; Rats; Rats, Wistar; Receptors, Purinergic; Receptors, Purinergic P1; Theophylline; Time Factors