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Updated: Jun 16, 2026
En Face Detection of Nitric Oxide and Superoxide in Endothelial Layer of Intact Arteries
Published on: February 25, 2016
Decreased arteriolar tetrahydrobiopterin is linked to superoxide generation from nitric oxide synthase in mice fed
Timothy R Nurkiewicz1, Guoyao Wu, Peng Li
1Center for Cardiovascular and Respiratory Sciences, West Virginia University, School of Medicine, Morgantown, WV 26506-9105, USA.
Objective:
Impaired endothelium-dependent arteriolar dilation in mice fed high salt (HS) is due to local oxidation of nitric oxide (NO) by superoxide anion (O(2) (-)). We explored the possibility that "uncoupled" endothelial nitric oxide synthase (eNOS) is the source of this O(2) (-).
Methods:
Levels of L-arginine (L-Arg), tetrahydrobiopterin (BH(4)), and O(2) (-) (hydroethidine oxidation) were measured in spinotrapezius muscle arterioles of mice fed normal salt (0.45%, NS) or (4%, HS) diets for 4 weeks, with or without dietary L-Arg supplementation. The contribution of NO to endothelium-dependent dilation was determined from the effect of N(omega)-nitro-L-arginine methyl ester (L-NAME) on responses to acetylcholine (ACh).
Results:
Arterioles in HS mice had lower [BH(4)] and higher O(2) (-) levels than those in NS mice. ACh further increased arteriolar O(2) (-) in HS mice only. L-Arg supplementation prevented the reduction in [BH(4)] in arterioles of HS mice, and O(2) (-) was not elevated in these vessels. Compared to NS mice, arteriolar ACh responses were diminished and insensitive to L-NAME in HS mice, but not in HS mice supplemented with L-Arg.
Conclusions:
These findings suggest that eNOS uncoupling due to low [BH(4)] is responsible for O(2) (-) generation and reduced NO-dependent dilation in arterioles of mice fed a HS diet.
