Objective:To investigate the effect of Amadori glycated serum albumin (AGSA) on diacylglycerol-protein kinase C (PKC) cascade in cultured retinal blood vessels of bovine. Methods: Glycated serum albumin was prepared by incubating sterile-filtered normal serum albumin for five days at 37℃ with 25mmol/L glucose in phosphated buffered saline(PBS).Albumin incubated for the same period in PBS without glucose was used as control(normal albumin

NA).Diacyglycerol level and PKC activity were determined in blood vessels incubated in media containing 10% nonglycated serum albumin (NSA) or AGSA

ant 5.5mmol/L glucose versus 20mmol/L glucose for 24 or 72 hours with or without 50 mmol/L d-α-tocopherol. Results: In blood vessels cultured for 24 hours in 5.5 mmol/L glucose

the relative ratio for diacyglycerol level in vessels supplemented with AGSA compared with the level exposed to NSA was l.76

and PKC activity in vessels supplemented with AGSA was also higher than the level exposed to NSA.The relative ratio for diacylglycerol level and PKC activity in vessels cultured in 20mmol/L glucose for 72 hours compared with that in vessels cultured in 5.5mmol/L glucose was 2.44

and 2.62 respectively.20mmol/L glucose also augmented the AGSA induced increase in diacylglycerol level and PKC activity relative to that observed in 5.5mmol/L glucose concentration.(Relative ratio of diacylglycerol level and PKC activity in cell cultured for 72 hours in 20mmol/L glucose supplemented with AGSA versus 5.5mmol/L glucose was 3.47

4.54 respectively).D-α-tocopherol can prevent activation of diacyglycerol-PKC cascade induced by high glucose and/or AGSA. Conclusion: AGSA activate diacyglycerol-PKC pathway by mechanisms that are operative under normoglycemic condition

which may contribute to the development of diabetic retinopathy.