[Effect of high glucose condition on the secretion of TGF beta by cultured macrovascular endothelial cells of the diabetic rat].

OBJECTIVE: This study was designed to examine the secretion of TGF-beta by cultured rat thoracic aortic endothelial cells of the diabetic rats under high gluocose condition. METHODS: First we created diabetic rat models, then the thoracic aortic endothelial cells of the diabetic rats were isolated and cultured in 10% FBS-RPMI 1640 media with various high glucose concentrations (12.5 mmol/L, 25 mmol/L or 50 mmol/L D-glucose), high glucose and TNF-alpha or high glucose and insulin for 48 hours, and the supernatant obtained from the cultured aortic endothelial cells was collected. The level of TGF-beta 1 in the supernatant was measured using a standard bioassay, which utilizes the TGF-beta 1 sensitive Mv1Lu (CLL-64) Mink lung epithelial cell line, and the production of endothelin (ET) in the supernatant was also assessed by RIA (radio immol/Lunoassay). RESULTS: Both total TGF-beta 1 (406 +/- 29 vs 189 +/- 23 pg/ml, P < 0.05) and active TGF-beta 1 (161 +/- 24 vs 39.5 +/- 8 pg/ml) secreted by the cultured aortic endothelial cells under high glucose condition (25 mmol/L) were significantly increased as compared with control. TNF-alpha could enhance the effect of high glucose on the secretion of TGF-beta 1, whereas insulin could inhibit it. With various high glucose concentrations, the levels of ET were increased. Also TNF-alpha enhanced it and insulin inhibited it. CONCLUSION: TGF-beta 1 may be involved in the development of diabetic macrovascular complication.