BACKGROUND: The adhesion of polymorphonuclear neutrophils (PMNs) to the coronary endothelium is an crucial step in PMN-mediated reperfusion injury. The purpose of this study was to investigate whether thiopental inhibits the postischemic coronary vascular adhesion of PMNs, and results in reduced postischemic myocardial dysfunction in isolated guinea pig hearts. METHODS: Hearts (n = 6-8/group) were isolated from male-guinea pigs and perfused with modified Krebs-Henseleit solution. After isolation, hearts were stabilized for 10 minutes, perfused for 15 minutes, allowed an ischemic period for 30 minutes, and a reperfusion period of 60 minutes (C group). In the P group, a bolus of 1x10(6) PMNs was infused 2 minutes after reperfusion, and in the T group additional thiopental was infused 5 minutes after the start of reperfusion, and PMNs were infused on 2 minutes after reperfusion. PMN adhesion (%), LVDP, LVEDP, +/-dP/dt, HR, and CF were measured pre- and postischemia. RESULTS: The addition of thiopental (25 microM) to the perfusate reduced the postischemic coronary vascular adhesion of PMNs (72.5+/-4.5% vs 40.0+/-7.4%, P < 0.05) and prevented postischemic myocardial dysfunction compared with group P (73.5+/-6.9% vs 48.4+/-3.0%, P < 0.05). CONCLUSIONS: Postischemic myocardial dysfunction is significantly more pronounced after PMN infusion. Thiopental reduced the postischemic coronary vascular adhesion of PMNs and attenuated the myocardial dysfunction, which was responsible at least in part, for the cardioprotective effect.