Obejctive To study the effects of high concentrations of glucose, insulin and oxidized low density lipoprotein (ox LDL) on apoptosis in cultured bovine aortic endothelial cells (ECs) Methods For qualitative determination of EC apoptosis, acridine orange (AO)/ethidium bromide (EB) staining and DNA agarose gels electrophoresis were used Cellular DNA fragmentation ELISA measured apoptosis by quantitating the fragmentation of 5 bromo 2’ deoxyuridine labeled DNA Results High concentrations of glucose (20?mmol/L, 40?mmol/L), insulin (3000?μU/ml) and ox LDL (50?μg/ml, 100?μg/ml) induced concentration and time dependent apoptosis in ECs They had a synergetic effect on EC apoptosis The combined effect of high concentration of glucose, insulin and ox LDL was greater than any two of them; the effect of two was greater than one alone Low concentration of insulin (30?μU/ml) decreased apoptosis in ECs induced by high concentrations of glucose (40? mmol/L), but no similar effect occurred with ox LDL (100?μg/ml) Conclusion High ambient glucose, insulin and ox LDL can induce excessive apoptosis in cultured ECs, and low ambient insulin can prevent EC apoptosis Excessive EC apoptosis induced by the separate or synergetic effect of hyperglycemia, hyperinsulinemia and hyperlipidemia may be one of the reasons for loss of endothelial integrity, dysfunction of the vascular endothelium and increased plasma membrane permeability, which are all involved in the development of diabetic macrovascular complications Obejctive To study the effects of high concentrations of glucose, insulin and oxidized low density lipoprotein (ox LDL) on apoptosis in cultured bovine aortic endothelial cells (ECs) Methods For qualitative determination of EC apoptosis, acridine orange (AO) / ethidium bromide ) staining and DNA agarose gels electrophoresis were used Cellular DNA fragmentation ELISA measured apoptosis by quantitating the fragmentation of 5 bromo 2 ’deoxyuridine labeled DNA Results High concentrations of glucose (20? mmol / L, 40? mmol / L) induced concentration and time dependent apoptosis in ECs They had a synergetic effect on EC apoptosis The combined effect of high concentration of glucose, insulin and ox LDL was (50 μg / ml, 100 μg / ml) greater than any two of them; the effect of two was greater than one alone Low concentration of insulin (30 μU / ml) decreased apoptosis in ECs induced by high concentrations of glucose (40? mmol / L), but n o similar effect occurred with ox LDL (100 μg / ml) Conclusion High ambient glucose, insulin and ox LDL can induce excessive apoptosis in cultured ECs, and low ambient insulin can prevent EC apoptosis induced by the separate or synergetic effect of hyperglycemia, hyperinsulinemia and hyperlipidemia may be one of the reasons for loss of endothelial integrity, dysfunction of the vascular endothelium and increased plasma membrane permeability, which are all involved in the development of diabetic macrovascular complications