The effect of droxicainide was investigated in a rabbit model of myocardial ischemia and reperfusion. The rabbits were randomized to either a saline-treated control group (n=18) or a droxieainide-treated group (n=11). In the control group, the incidence of ventricular fibrillation after coronary ligation was 14/18 (77.7%) and nine died (64.3%). Ventricular fibrillation occurred in eight (72.7%) droxieainide treated rabbits, but all reverted spontaneously (P

Various studies have suggested that adrcnergic activtaion may contribute to deleterious effects on myocardial ischemia. However, very little is known about it s role during reperfusion. This study was designed to explore the relationship between endogenous norepinephrine (NE) and reperfusion injury in intact rabbits. In rabbits(n=5) 35 min of coronary occlusion without reperfusion thc myocardial NE content of the ischemic area was not significantly different from that of the non-ischemic area, nor was tissue calcium content in both areas, while, in 35 min of occlusion followed by 10 min of reperfusion group(n=5), the tissue NE was markedly reduced in reperfused area accompanying significant calcium overloading. These studies suggest that the postischemic reperfusion injury may be, in part, due to endogenous catecholamine release during reperfusion.

AIM: To study the alterations of heme oxygenase-1 mRNA in vascular smooth muscle cells(VSMC) induced by lipopolysaccharide(LPS) and the role of heme oxygenase(HO)/carbon monoxide(CO)pathway in the disorders of regulation of cardiovascular system by LPS. METHODS: LPS (final concentrations 10 mg/L,30 mg/L and 50 mg/L) was added in cultured VSMCs for 6 h respectively or 10 mg/L LPS for 9 h and 18 h. MDA content, LDH release and the rate of trypan blue uptake of VSMC were measured. HO-1 mRNA expression was examined by Northern Blot. RESULTS: VSMC HO-1 mRNA expression was increased gradually with the increasing of LPS concentration. When final concentration of LPS was 50 mg/L, the HO-1 mRNA expression of VSMC was increased by 176.7% compared with control. When LPS final concentration was 10 mg/L, the HO-1 mRNA expression increased gradually along with the culture time. When cultured for 18 h, the HO-1 mRNA expression of VSMC was increased by 195.6% compared with control. Only at LPS 50 mg/L for 6 h and 10 mg/L for 18 h, the rate of trypan blue uptake，MDA content and LDH release were significantly increased. CONCLUSION: LPS can induce the HO-1 mRNA expression of VSMC and that were dose-dependent and time-dependent. The inducible HO may play an important role in the pathogenesis of vascular system under LPS.

AIM: To study the alterations of heme oxygenase-1 mRNA in vascular smooth muscle cells(VSMC) induced by lipopolysaccharide(LPS) and the role of heme oxygenase(HO)/carbon monoxide(CO)pathway in the disorders of regulation of cardiovascular system by LPS. METHODS: LPS (final concentrations 10 mg/L,30 mg/L and 50 mg/L) was added in cultured VSMCs for 6 h respectively or 10 mg/L LPS for 9 h and 18 h. MDA content, LDH release and the rate of trypan blue uptake of VSMC were measured. HO-1 mRNA expression was examined by Northern Blot. RESULTS: VSMC HO-1 mRNA expression was increased gradually with the increasing of LPS concentration. When final concentration of LPS was 50 mg/L, the HO-1 mRNA expression of VSMC was increased by 176.7% compared with control. When LPS final concentration was 10 mg/L, the HO-1 mRNA expression increased gradually along with the culture time. When cultured for 18 h, the HO-1 mRNA expression of VSMC was increased by 195.6% compared with control. Only at LPS 50 mg/L for 6 h and 10 mg/L for 18 h, the rate of trypan blue uptake,MDA content and LDH release were significantly increased. CONCLUSION: LPS can induce the HO-1 mRNA expression of VSMC and that were dose-dependent and time-dependent. The inducible HO may play an important role in the pathogenesis of vascular system under LPS. [