Altered active but not passive properties of mesenteric resistance arteries from the vitamin E‐deprived rat

We tested the hypothesis that lowering antioxidant protection through dietary vitamin E deprivation would alter active and passive mechanical properties in resistance arteries of the rat. Specifically, we hypothesized that vascular tone in isolated mesenteric arteries of the vitamin E‐deprived rats would be altered due to impaired endothelial influences of nitric oxide and/or prostaglandins. Lumen diameter and wall thickness were measured in pressurized arteries (≈amp;250 μm diameter) from control ( n =9) and vitamin E deprived ( n =9) Sprague‐Dawley female rats by use of a dimension analysing system. Treatment with a cyclo‐oxygenase inhibitor (meclofenamate) did not affect the basal vascular tone in either group. Treatment with a nitric oxide synthase inhibitor (N G ‐methyl‐ L ‐arginine) caused a significant increase in basal tone only in the vitamin E‐deprived rats (% tone: 6.2±1.1 vs 1.2±0.3%; P <0.05). When tone was induced to 25% of the initial diameter with phenylephrine, treatment with the nitric oxide synthase inhibitor resulted in a greater potentiated tone in the vitamin E‐deprived rats compared to the controls (26.5±2.7 vs 16.4±3.4%; P <0.05); suggesting a greater nitric oxide affect in the vessels from the vitamin E‐deprived rats. Meclofenamate treatment in the induced tone arteries significantly relaxed (−17.4±4.0%; P <0.05) only the arteries from the vitamin E‐deprived rats, indicating that a vasoconstrictor was modifying tone. The passive characteristics of distensibility and stress‐strain relationship were not different between the two groups of rats. In summary, vitamin E deprivation in the rat enhanced the modulation of vascular tone by both the nitric oxide and cyclo‐oxygenase pathways but did not alter passive characteristics of mesenteric arteries.British Journal of Pharmacology (1998) 123 , 275–280; doi: 10.1038/sj.bjp.0701639