Impaired dilation of the facialis artery in sph/sph mice in response to stimulation with acetylcholine. Facialis arteries (180-250 μm) were isolated from control (■,□) and sph/sph (▴,▵) mice as described under “Methods.” Pressurized arteries were preconstricted with the thromboxane A2 agonist U46619 (10−9-10−8 mol/L; 15-hydroxy-11α,9α-(epoxymethano)prosta-5,13-dienoic acid). Vessel dilation in response to stimulation with acetylcholine (ACh; 10−7 to 10−4 mol/L) was recorded in the absence (■,▴) and presence (□,▵) of the NO antagonist l-NAME (100 μM). Data are presented as mean (± SEM) for n = 9 vessels from n = 7 control mice, and n = 8 vessels from n = 6 sph/sph mice. Normal mice were all older than 12 weeks of age; n = 3 sph/sph mice were 7 to 10 weeks of age, and n = 3 were 13 to 18 weeks of age. No differences in vessel dilation were observed in younger versus older sph/sph mice. *P < .005, control vessel dilation without l-NAME compared with sph/sph vessel dilation without l-NAME.
