The effects of glucose, insulin and oxidized low density lipoprotein on apoptosis in vascular endothelial cells.
OBJECTIVE
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 microU/ml) and ox-LDL (50 micrograms/ml, 100 micrograms/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 microU/ml) decreased apoptosis in ECs induced by high concentrations of glucose (40 mmol/L), but no similar effect occurred with ox-LDL (100 micrograms/ml).


CONCLUSIONS
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.
Chai
W
W
Department of Endocrinology, First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China.
Chen
J
J
Wang
H
H
Shen
J
J
Ma
L
L
Ma
X
X
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002417:Cattle; D002478:Cells, Cultured; D053938:DNA Fragmentation; D003925:Diabetic Angiopathies / Q000209:etiology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D008077:Lipoproteins, LDL / Q000494:pharmacology*
D007328:Insulin; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; D005947:Glucose