N6-(3-iodobenzyl)-adenosine-5'-N-methylcarboxamide confers cardioprotection at reperfusion by inhibiting mitochondrial permeability transition pore opening via glycogen synthase kinase 3 beta.

Abstract

Although the adenosine A(3) receptor agonist N(6)-(3-iodobenzyl)-adenosine-5'-N-methylcarboxamide (IB-MECA) has been reported to be cardioprotective at reperfusion, little is known about the mechanisms underlying the protection. We hypothesized that IB-MECA may protect the heart at reperfusion by preventing the opening of mitochondrial permeability transition pore (mPTP) through inactivation of glycogen synthase kinase (GSK) 3beta. IB-MECA (1 microM) applied during reperfusion reduced infarct size in isolated rat hearts, an effect that was abrogated by the selective A3 receptor antagonist 1,4-dihydro-2-methyl-6-phenyl-4-(phenylethynyl)-3,5-pyridinedicarboxylic acid 3-ethyl-5-[(3-nitrophenyl)-methyl]ester (MRS1334) (100 nM). The effect of IB-MECA was abrogated by the mPTP opener atractyloside (20 microM), implying that the action of IB-MECA may be mediated by inhibition of the mPTP opening. In cardiomyocytes, IB-MECA attenuated oxidant-induced loss of mitochondrial membrane potential (DeltaPsim), which was reversed by MRS1334. IB-MECA also reduced Ca2+-induced mitochondrial swelling. IB-MECA enhanced phosphorylation of GSK-3beta (Ser9) upon reperfusion, and the GSK-3 inhibitor 3-(2,4-dichlorophenyl)-4-(1-methyl-1H-indol-3-yl)-1H-pyrrole-2,5-dione (SB216763) (3 microM) mimicked the protective effect of IB-MECA by attenuating both infarction and the loss of DeltaPsim. In addition, the effect of IB-MECA on GSK-3beta was reversed by wortmannin (100 nM), and IB-MECA was shown to enhance Akt phosphorylation upon reperfusion. In contrast, rapamycin (2 nM) failed to affect GSK-3beta phosphorylation by IB-MECA, and IB-MECA did not alter phosphorylation of either mTOR (Ser2448) or 70s6K (Thr389). Taken together, these data suggest that IB-MECA prevents myocardial reperfusion injury by inhibiting the mPTP opening through the inactivation of GSK-3beta at reperfusion. IB-MECA-induced GSK-3beta inhibition is mediated by the PI3-kinase/Akt signal pathway but not by the mTOR/p70s6K pathway.

• Authors: Sung-Sik Park, Hong Zhao, Yeongho Jang, Robert A Mueller, Zhelong Xu
• Journal: The Journal of pharmacology and experimental therapeutics (J Pharmacol Exp Ther) Vol. 318 Issue 1 Pg. 124-31 (Jul 2006) ISSN: 0022-3565 [Print] United States
• PMID: 16611852 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cardiotonic Agents
• Mitochondrial Membrane Transport Proteins
• Mitochondrial Permeability Transition Pore
• N(6)-(3-iodobenzyl)-5'-N-methylcarboxamidoadenosine
• Glycogen Synthase Kinase 3 beta
• Gsk3b protein, rat
• Glycogen Synthase Kinase 3
• Adenosine

Topics

• Adenosine (analogs & derivatives, pharmacology, therapeutic use)
• Animals
• Cardiotonic Agents (pharmacology, therapeutic use)
• Glycogen Synthase Kinase 3 (antagonists & inhibitors, metabolism)
• Glycogen Synthase Kinase 3 beta
• Male
• Mitochondrial Membrane Transport Proteins (antagonists & inhibitors, metabolism)
• Mitochondrial Permeability Transition Pore
• Myocardial Reperfusion Injury (enzymology, prevention & control)
• Rats
• Rats, Wistar