1. The aim of the present investigation was to evaluate the effect of cloricromene on myocardial infarct size, regional myocardial blood flow and neutrophil accumulation in a canine model of ischaemia-reperfusion.
2. Dogs were instrumented to measure blood pressure, left anterior descending (LAD) coronary flow (flow probe) and regional myocardial blood flow (coloured microspheres), Two groups were studied: (i) CLO (n = 8) received an infusion of cloricromene (15 mu g/kg per min); and (ii) VEH (It = 8) received saline. Infusions began at the onset of ischaemia (60 min) and continued through reperfusion (180 min).
3. Haemodynamic responses were not different between groups. CIoricromene reduced the area of necrosis expressed as a percentage of the area at risk from 35 +/- 3% in the VEH group to 23 +/- 4% in the CLO group (P<0.05), Regional myocardial blood how in the ischaemic region was different between groups; VEH dogs showed an early reperfusion hyperaemia followed by a progressive reduction in how while CLO dogs exhibited a gradual increase in reflow in the absence of an early hyperaemic response (P<0.05). Left anterior descending how was enhanced during the reperfusion period in the CLO group compared with VEH (P<0.05), Cloricromene reduced polymorphonuclear neutrophil (PMN) infiltration (myeloperoxidase activity) in all myocardial regions when compared with VEH (non-ischaemic zone, 0.34 +/- 0.54 vs 0.05 +/- 0.01 IU/100 mg; ischaemic zone, 2.03 +/- 0.80 vs 0.24 +/- 0.08 IU/100 mg; and necrotic zone, 0.56 +/- 0.04 vs 3.59 +/- 1,09 IU/100 mg for VEH vs CLO groups, respectively; P<0,01), In a separate in vitro preparation, cloricromene reduced adherence of platelet-activating factor (PAF)-stimulated PMN to canine coronary endothelium. Stimulation of PMN by 100 nmol/L PAF resulted in adherence of 176 +/- 36 compared with 48 +/- 12 cells/mm(2) in PAF-stimulated PMN treated with 100 mu mol cloricromene (P<0.001).
4. These data indicate that cloricromene reduces myocardial infarct size in a canine model of ischaemia-reperfusion injury. Postischaemic blood how patterns are significantly different in cloricromene-treated dogs. Cloricromene-mediated reductions in infarct size, neutrophil accumulation and adherence may play a role in this effect.