Rat isolated heart model
Female Wistar rats (180–200g; total of 52) were anaesthetized with pentobarbital sodium (60mgkg−1 i.p.), and hearts were excised, mounted on a Langendorff apparatus and perfused in a constant pressure mode with modified Krebs–Henseleit bicarbonate buffer containing (mM) 118.5 NaCl, 24.8 NaHCO3, 4.7 KCl, 1.2 MgSO4, 1.2 KH2PO4, 2.5 CaCl2 and 10 glucose. A suture was passed around a major branch of the left coronary artery. After equilibration, hearts were subjected to 30min of regional ischemia by occluding the snared artery followed by 2h of reperfusion as depicted in Figure 1. Control hearts were subjected to only 30min of regional ischemia and then reperfusion. Four groups of hearts were treated with different vardenafil dosages (1, 10, 100 and 1000nM) during the reperfusion period starting 5min before reperfusion. In the next groups, one of three inhibitors was co-infused along with the protective vardenafil dose of 10nM. These inhibitors included the GC inhibitor ODQ (10μM) and the PKG inhibitor KT-5823 (1μM). Finally, three groups of hearts were treated with only ODQ or KT-5823, as noted above, to exclude independent effects of the blockers.
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