EFFECTS OF CHRONIC VITAMIN-E-DEFICIENCY ON VASCULAR FUNCTION - A STUDY OF SYMPATHETIC-NERVES, SMOOTH-MUSCLE AND ENDOTHELIUM OF THE MESENTERIC ARTERIAL BED OF THE RAT

1 Male rats were deprived as weanlings of dietary vitamin E for 2, 4, 6, 10 and 12 months. Mesenteric arterial beds from these rats and from age-matched controls were isolated and perfused with Krebs solution a t a constant flow rate (5 ml min(-1)). The function of perivascular sy mpathetic nerves, smooth muscle and endothelium was assessed. 2 At 12 months vitamin E deficient rats exhibited the characteristic symptoms of vitamin E deficiency, namely poor coat condition, muscle wasting, k yphoscoliosis and impaired gait. In the isolated mesenteric arterial b ed electrical field stimulation (EFS) of perivascular nerves (4-32 Hz, 90 V, 1 ms, for 30 s) elicited frequency-dependent vasoconstrictor re sponses which were unaffected by vitamin E deficiency except at 12 mon ths, at which age responses were significantly greater than those of t he controls at 24 and 32 Hz (P < 0.01). 3 Exogenous noradrenaline (NA; 0.15-500 nmol) elicited dose-dependent vasoconstriction which was sim ilar in vitamin E-deficient and control preparations at all ages. Pota ssium chloride (0.15 mmol) also produced similar vasoconstrictor respo nses in vitamin E-deficient and control preparations at each age. 4 To ne of the preparations was raised by continuous perfusion with methoxa mine (4-70 mu M), producing similar increases in perfusion pressure in vitamin E-deficient and control preparations at each age. Endothelium -dependent dose-dependent vasodilatation to adenosine 5'-triphosphate was significantly impaired in mesenteric arterial beds from 12 month-o ld vitamin E-deficient rats compared with the controls (P < 0.05). Rel axation to acetylcholine was not significantly different at any age. 5 Endothelium-independent vasodilatation to sodium nitroprusside was si milar in vitamin E-deficient rats and age-matched controls. 6 These re sults suggest that long term (12 months) deprivation of dietary vitami n E may impair endothelial function in mesenteric arteries of the rat. Sympathetic perivascular nerve constrictor function was increased at 12 months. There were no functionally expressed changes in the vascula r smooth muscle, which appears to be more resilient to the effects of oxidative stress in vitamin E deficiency.