title: Non-specific caspase inhibition reduces infarct size and improves post-ischaemic recovery in isolated ischaemic/reperfused rat hearts.
abstract: Myocardial ischaemia and reperfusion lead to myocardial cell death due, at least in part, to apoptotic mechanisms. Although cysteinyl aspartate-specific proteinase (caspase) activation is a major event and the most-cited culprit in the development of apoptosis, its potential contribution to ischaemic myocardial cell death is largely unknown. To study the role of caspase activation, isolated rat hearts (n=6 per group) were subjected to 30 min coronary artery occlusion followed by 120 min reperfusion. A non-selective [0.1 or 0.5 microM acetyl-Tyr-Val-Ala-Asp chloromethylketone (YVAD-cmk)] or selective caspase inhibitors [0.07 or 0.2 microM acetyl-Asp-Glu-Val-Asp-cmk (Ac-DEVD-cmk, caspase-3 inhibitor); 0.07 or 0.2 microM benzoxycarbonyl-Leu-Glu-OMe-His-Asp(OMe)-fluoromethylketone (z-LEHD-fmk, caspase-9 inhibitor)] were added to the perfusate at the start of reperfusion. Non-selective caspase inhibition with 0.1 or 0.5 microM YVAD-cmk limited infarct size: (21 +/- 4%, P<0.05; 17 +/- 3%, P<0.05, respectively) compared with the ischaemic/reperfused control (32 +/- 5%). In hearts treated with 0.1 or 0.5 microM caspase II non-selective inhibitor, the fraction of terminal-deoxynucleotidyl-transferase deoxyuridine nick end labelling (TUNEL)-positive myocyte nuclei in the infarcted zone was reduced from the ischaemic/reperfused non-treated control of 11.2 +/- 2.1% to 6.2 +/- 1.6% (P<0.05) and 1.2 +/- 0.2% (P<0.05), respectively. The recovery of post-ischaemic cardiac function (coronary flow, aortic flow and left-ventricular developed pressure) improved significantly with the application of the non-selective caspase inhibitor as well. In hearts perfused with specific caspase inhibitors (caspase-3 and caspase-9) there was no significant reduction in the infarct size, no improvement in post-ischaemic cardiac function and no reduction of apoptotic cell death. We conclude that non-specific inhibition of caspases may be therapeutically beneficial in myocardial ischaemia/reperfusion-induced damage, while selective caspase inhibitors may fail to prevent such reperfusion-induced injury in our model system.
authors.affiliation: Dept Pharmacology, School of Medicine, University of Debrecen, Hungary.
authors.forename: P
authors.initials: P
authors.lastname: Kovacs
authors.forename: I
authors.initials: I
authors.lastname: Bak
authors.forename: L
authors.initials: L
authors.lastname: Szendrei
authors.forename: M
authors.initials: M
authors.lastname: Vecsernyes
authors.forename: E
authors.initials: E
authors.lastname: Varga
authors.forename: I E
authors.initials: IE
authors.lastname: Blasig
authors.forename: A
authors.initials: A
authors.lastname: Tosaki
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D053148:Caspase 3; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use*; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000201:enzymology; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy* / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; C505410:Casp3 protein, rat; C506435:Casp9 protein, rat; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases