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Elevation of an endogenous inhibitor of nitric oxide synthase in diabetic rat serum
Aim:
To study the endogenous inhibitor of NO synthase NG,NG-dimethyl-arginine (DMA) in the diabetic rat serum.
Methods:
In streptozocin-induced diabetic rats, the serum DMA level and endothelium-dependent vasorelaxation to acetylcholine (ACh) were determined.
Results:
The serum DMA concentration was increased in the diabetic rats compared with their age-matched controls (5.4 +/- 1.0 vs 0.7 +/- 0.3 mumol.L-1, P < 0.01). The serum malondialdehyde (MDA) level was also increased in the diabetic rats compared with controls (2.5 +/- 0.3 vs 1.5 +/- 0.1 mumol.L-1, P < 0.01). Vasodilator response to ACh was impaired in diabetic thoracic aortas, which was improved by preincubation with L-arginine 1 mmol.L-1.
Conclusion:
Hyperglycemia elevated the endogenous DMA content, which contributed to attenuated endothelium-dependent vasorelaxation in streptozocin-induced diabetic rats.