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.