| Object: To compare the effects of intermittent and constant high glucose media onthe mRNA and protein expressions of VCAM-1 and ICAM-1, as well as the production of NO in cultured human umbilical endothelial cells so as to explore the pathological effects of intermittent hyperglycemia on diabetes vascular complication.Methods: Human umbilical vein endothelial cells (HUVECs) were grown toconfluence and were exposed for 7 days to 5.5 mmol/1 glucose (normal), 20 mmol/1 glucose (constant high glucose), 5.5 mmol/1 alternating with 20 mmol/1 glucose per 8hours (intermittent high glucose) and 20 mmol/1 mannitol respectively. The VCAM-1, ICAM-1 mRNA expression was determined by reverse transcript polymerase chain reaction (RT-PCR). The VCAM-1, ICAM-1 protein expression was detected by immunocytochemistry. The production of NO was measured with nitrate reduction test.Results: (1) In cultured HUVECs, exposure to constant high glucose andintermittent high glucose for 7days, caused a marked increase in the mRNA expressions of VCAM-1 and ICAM-1. Compared with cells exposed to normal glucose, the expressions of VCAM-1 mRNA were increased to 151% (p<0.01) and 212% (p<0.001) respectively, which was even more in intermittent high glucose than in constant high glucose; the expressions of ICAM-1 mRNA were increased to 173% (p<0.01) and 198% (p<0.01) respectively, which was further enhanced in intermittent high glucose (p<0.01). (2) After HUVECs were exposed to constant high glucose and intermittent high glucose for 7days, it caused a significant increase in the protein expressions of VCAM-1 and ICAM-1. Compared with cells exposed to normal glucose, the expressions of VCAM-1 protein were increased to 222% (p<0.001) and 487% (p<0.001) respectively, and the latter increased more significantly (p<0.01); the ICAM-1 protein were increased to 150% (p<0.05) and 228% (p<0.01) respectively, which was further amplified in intermittent high glucose (p<0.01).
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