Korean J Physiol Pharmacol.  2000 Jun;4(3):263-270.

Impaired endothelium-dependent relaxation is mediated by reduced production of nitric oxide in the streptozotocin-induced diabetic rats

• Park KS
• Kim CS
• Kang SW
• Park JB
• Kim KJ
• Chang SJ
• Jeon BH

Abstract

To evaluate the involvement of nitric oxide production on the endothelium-dependent relaxation in diabetes, we have measured vascular and endothelial function and nitric oxide concentration, and the expression level of endothelial nitric oxide synthase in the streptozotocin-induced diabetic rats. Diabetic rats were induced by the injection of streptozotocin (50 mg/kg i.v.) in the Sprague-Dawley rats. Vasoconstrictor responses to nonrepinephrine (NE) showed that maximal contraction to norepinephrine (10(-5) M) was significantly enhanced in the aorta of diabetic rats. Endothelium-dependent relaxation induced by acetylcholine was markedly impaired in the aorta of diabetic rats, these responses were little improved by the pretreatment with indomethacin. However, endothelium-independent relaxation induced by nitroprusside was not altered in the diabetic rats. Plasma nitrite and nitrate (NO2/3) levels in diabetic rats were significantly lower than innon-diabetic rats. Western blot analysis using a monoclonal antibody against endothelial cell nitric oxide synthase (eNOS) revealed that the protein level was lower in the aorta of diabetic rats than in non-diabetic rats. These data indicate that nitric oxide formation and eNOS expression is reduced in diabetes, and this would, in part, account for the impaired endothelium-dependent relaxation in the aorta of streptozotocin-induced diabetic rats.

MeSH Terms

Acetylcholine
Animals
Aorta
Blotting, Western
Endothelial Cells
Indomethacin
Nitric Oxide Synthase
Nitric Oxide Synthase Type III
Nitric Oxide*
Nitroprusside
Norepinephrine
Plasma
Rats*
Rats, Sprague-Dawley
Relaxation*
Streptozocin
Acetylcholine
Indomethacin
Nitric Oxide
Nitric Oxide Synthase
Nitric Oxide Synthase Type III
Nitroprusside
Norepinephrine
Streptozocin