During the past five years we developed and characterized a model of spontaneously beating, isolated rabbit heart, perfused with purified human PMNL, showing that PMNL activation causes cys-LT formation through PMNL-endothelial cell transcellular synthesis, resulting in increased coronary resistance and cardiac damage . Under the working hypothesis that 5-lipoxygenase inhibition may result in cardio-protection in cardiac ischemia, we studied the effect of a 5-lipoxygenase inhibitor, BAY X1005 , both in the PMNL-perfused isolated rabbit heart and in an in vivo model of cardiac ischemia induced by permanent ligation of the left descending coronary artery.
ANIMALS AND METHODS
Rabbit hearts were isolated and perfused retrogradely through the aorta in the Langendorff mode at constant flow. Coronary perfusion pressure (CPP), left ventricular pressure and left ventricular end-diastolic pressure (LVEDP) were monitored continuously. Blood cells were prepared according to the method of Haslett et al . PMNL (5×106 cells) were supplied with calcium (2 mM) and magnesium (0.5 mM), and infused into the perfusing medium (50 mL) of recirculating hearts, with or without pretreatment of the heart with BAY X1005 (1 pM). At the end of the experiment, the entire heart reservoir (approximately 45 mL) was collected, spiked with 50,000 dpm (=disintegrations per minute??) 3H-LTD4 as well as 25 ng of prostaglandin B2, extracted and analyzed by reversed phase high performance liquid chromatography with diode-array ultraviolet detection.