Altered active but not passive properties of mesenteric resistance arteries from the vitamin E-deprived rat.
1 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. 2 Lumen diameter and wall thickness were measured in pressurized arteries (approximately 250 microm diameter) from control (n=9) and vitamin E deprived (n=9) Sprague-Dawley female rats by use of a dimension analysing system. 3 Treatment with a cyclo-oxygenase inhibitor (meclofenamate) did not affect the basal vascular tone in either group. Treatment with a nitric oxide synthase inhibitor (NG-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. 4 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.
Davidge
S T
ST
Perinatal Research Centre, University of Alberta, Edmonton, Canada.
Gandley
R E
RE
McLaughlin
M K
MK
D000818:Animals; D001835:Body Weight / Q000502:physiology; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000503:physiopathology; D005260:Female; D008638:Mesenteric Arteries / Q000503:physiopathology*; D009129:Muscle Tonus / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D009569:Nitric Oxide / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014655:Vascular Resistance / Q000502:physiology*; D014811:Vitamin E Deficiency / Q000503:physiopathology*
D009569:Nitric Oxide