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Publications (4)12.86 Total impact

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    ABSTRACT: Myocardial damage from ischemia/reperfusion injury can be minimized through endogenous protective mechanisms, including activation of A1 adenosine receptors. Transgenic mice with cardiac-specific A1 adenosine receptor overexpression (A1AR Trans) have demonstrated functional and metabolic tolerance to in vitro and in vivo myocardial ischemia/reperfusion injury. The purpose of this investigation is to examine the role of p38 MAP kinase in A1 receptor-mediated cardioprotection. Activation of p38 MAPK by A1 adenosine receptor stimulation was evaluated in neonatal rat cardiomyocytes subjected to simulated ischemia. A1 activation by cyclopentyladenosine decreased cell death and simultaneously enhanced p38 phosphorylation by simulated ischemia. The role of p38 MAP kinase activation in cardioprotection with A1 adenosine receptor overexpression was evaluated in isolated perfused hearts from A1AR Trans mice subjected to 20 min ischemia and 30 min reperfusion. Inhibition of p38 MAPK activity with 10 μM SB-203580 prior to ischemia and during reperfusion decreased postischemic total functional recovery in A1AR Trans hearts from 54 ± 1 to 27±7% of maximal and increased final EDP from 10±3 mmHg to 34±8 mmHg. A1 adenosine receptor-mediated activation of p38 MAP kinase in cardiomyocytes is involved in the protection of cells from ischemic death. Tolerance to ischemic injury by A1 receptor overexpression is dependent upon activation of p38 MAPK. These findings suggest that adenosine A1 mediated cardioprotection in transgenic mice involves activation of the p38 MAP kinase cascade. Drug Dev. Res. 58:439–446, 2003. © 2003 Wiley-Liss, Inc.
    No preview · Article · Apr 2003 · Drug Development Research
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    ABSTRACT: We tested the hypothesis that myocardial ischemia-reperfusion (I/R)-induced apoptosis is attenuated in transgenic mice overexpressing cardiac A(1) adenosine receptors. Isolated hearts from transgenic (TG, n = 19) and wild-type (WT, n = 22) mice underwent 30 min of ischemia and 2 h of reperfusion, with evaluation of apoptosis, caspase 3 activity, function, and necrosis. I/R-induced apoptosis was attenuated in TG hearts. TG hearts had less I/R-induced apoptotic nuclei (0.88 +/- 0.10% vs. 4.22 +/- 0.24% terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells in WT, P < 0.05), less DNA fragmentation (3.30 +/- 0.38-fold vs. 4.90 +/- 0.39-fold over control in WT, P < 0.05), and less I/R-induced caspase 3 activity (145 +/- 25% over nonischemic control vs. 234 +/- 31% in WT, P < 0.05). TG hearts also had improved recovery of function and less necrosis than WT hearts. In TG hearts pretreated with LY-294002 (3 microM) to evaluate the role of phosphosinositol-3-kinase in acute signaling, there was no change in the functional protection or apoptotic response to I/R. These data suggest that cardioprotection with transgenic overexpression of A(1) adenosine receptors involves attenuation of I/R-induced apoptosis that does not involve acute signaling through phosphoinositol-3-kinase.
    Preview · Article · Mar 2003 · AJP Heart and Circulatory Physiology
  • SE Regan · RJ Cerniway · RM Broad · AM Byford · GP Matherne

    No preview · Article · Apr 2002 · Pediatric Research
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    ABSTRACT: To characterize effects of A(3) adenosine receptor (A(3)AR) activation and gene knock-out on responses to ischemia-reperfusion in mouse heart. Perfused hearts from wild-type and A(3)AR gene knock-out (A(3)AR KO) mice were subjected to 20 min ischemia and 30 min reperfusion. Functional responses were assessed and changes in energy metabolism and cytosolic pH monitored via 31P-NMR spectroscopy. Selective A(3)AR agonism with 100 nM 2-chloro-N(6)-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (chloro-IB-MECA) enhanced post-ischemic contractile recovery without altering contracture development in wild-type hearts, an effect unrelated to non-selective activation of A(1) or A(2) adenosine receptors. Chloro-IB-MECA also improved recovery in hearts overexpressing A(1)ARs. Paradoxically, post-ischemic recovery was enhanced by A(3)AR KO. Developed pressure, +dP/dt, and -dP/dt all recovered to higher levels in A(3)AR KO (70-80% of pre-ischemia) vs. wild-type hearts (45-50% of pre-ischemia) (P<0.05). Enhanced recovery was unrelated to recoveries of ATP, phosphocreatine (PCr), inorganic phosphate (P(i)), energy state ([ATP]/[ADP] x [P(i)], DeltaG(ATP)) or cytosolic pH. Selective A(3)AR activation is cardioprotective in wild-type hearts and hearts overexpressing A(1)ARs, yet A(3)AR gene deletion generates an ischemia-tolerant phenotype without altering energy metabolism or pH. This may be due to compensatory changes or undefined genotypic differences in A(3)AR KO vs. wild-type hearts.
    No preview · Article · Feb 2002 · Cardiovascular Research