Endothelium-derived hyperpolarizing factor does not contribute to the decrease in endothelium-dependent relaxation in...

Area of Science:

• Vascular biology
• Diabetic complications
• Pharmacology

Background:

• Diabetes mellitus is associated with endothelial dysfunction.
• Endothelium-dependent relaxation is often impaired in diabetic states.
• The roles of nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF) in this impairment are not fully elucidated.

Purpose of the Study:

• To investigate the contribution of EDHF to impaired endothelium-dependent relaxation in the aorta of streptozotocin-induced diabetic rats.
• To differentiate the roles of NO and EDHF in acetylcholine-induced relaxation in diabetic aortas.

Main Methods:

• Aortic rings from streptozotocin-induced diabetic and control rats were used.
• Relaxation responses to acetylcholine were measured in the presence and absence of N omega-L-nitro-arginine methylester (L-NAME) to inhibit NO.
• Relaxation responses were also assessed with tetraethylammonium chloride (TEA) to inhibit EDHF.

Main Results:

• Acetylcholine-induced relaxation was significantly reduced in diabetic rat aortas compared to controls.
• Sodium nitroprusside-induced relaxation was comparable between diabetic and control groups, indicating preserved smooth muscle function.
• Inhibition of NO (L-NAME) caused a greater rightward shift in the dose-response curve of acetylcholine in control aortas than in diabetic aortas.
• Inhibition of EDHF (TEA) caused similar rightward shifts in both control and diabetic aortas.

Conclusions:

• Endothelium-derived NO contributes to the impairment of acetylcholine-induced relaxation in diabetic rat aortas.
• EDHF does not play a significant role in the observed impairment of endothelium-dependent relaxation in this model of diabetes.