ELEVATION OF AN ENDOGENOUS INHIBITOR OF NITRIC-OXIDE SYNTHASE IN DIABETIC RAT SERUM

AIM: To study the endogenous inhibitor of NO synthase N-G;N-G-dimethyl -arginine (DMA) in the diabetic rat serum. METHODS: In streptozocin-in duced diabetic rats, the serum DMA level and endothelium-dependent vas orelaxation to acetylcholine (ACh) were determined. RESULTS: The serum DMA concentration was increased in the diabetic rats compared with th eir age-matched controls (5.4 +/- 1.0 vs 0.7 +/- 0.3 mu mol . L-1, P < 0.01). The serum malondialdehyde (MDA) level was also increased in th e diabetic rats compared with controls (2.5 +/- 0.3 vs 1.5 +/- 0.1 mu mol . L-1, P < 0.01). Vasodilator response to ACh was impaired in diab etic thoracic aortas, which was improved by preincubation with L-argin ine 1 mmol . L-1. CONCLUSION: Hyperglycemia elevated the endogenous DM A content, which contributed to attenuated endothelium-dependent vasor elaxation in streptozocin-induced diabetic rats.