Supplement Selenium Effect On Vascular Bioactive Substances In Rats Under The Hypoxia Condition

Objective Selenium is one of the indispensable nutrients for human beings. It plays important roles in cardiovascular system, lipid metabolism and cellular function. It has protective effects on cardiovascular system through antioxidant effect. Vascular bioactive substances significantly influence vasoconstriction and vasodilation. The plasma levels of vascular bioactive substances could be the assessment parameters of therapeutic effect in cardiovascular diseases and also be one of the monitoring indirect indicators of vascular status under the hypoxia environment. Qinghai province is located in the Qinghai Tibet Plateau, hypoxia significantly influences individuals’ health of the local citizens. The effects of selenium on vasoactive substances have not been reported. The aim of the study was to analyze the effects of selenium on releasing of vasoactive substances and vasomotor function and to explore the potential mechanism of selenium on cardiovascular system protection under the condition of hypoxia.Methods Total of 100 adult male SD rats were randomly divided into 6 groups, normal control and hypoxia control groups(10 rats per group) and four hypoxia with selenium supplement(at different dosages of selenium) groups(20 rats per groups). Selenium methionine powder was added to the lab chow diet to make the selenium supplementation diet for the rats except the control groups. The dosage of selenium was set at 5, 10, 20, and 40 times of the dietary intake level for the four dosage groups respectively. The rats were kept under standard animal rooms with free access of food and drinks. The rats in normal control group were not given any interruption, while the rest of the rats were kept in the hypoxia environment two hours per day for four weeks(the oxygen level was 8%, which was made through a hypoxia control box). At the end of experiment, under anaesthesia, the blood of animals was drawn through cardio-puncture with EDTA as the anticoagulant and plasma was collected after centrifugation at 3000 rpm for 10 minutes. The ELISA Kits were used to quantify the plasma levels of endothelin 1(ET-1), angiotensin II(Ang-II), calcitonin gene related peptide(CGRP), and tumor necrosis factor α(TNF-α).Results Plasma levels of ANG-II and ET-1 were significantly higher in rats in hypoxia control group than that in normal control group(P<0.05, P<0.01), but significantly lower in selenium supplemented rats compared with the nonsupplemented rats under hypoxia condition, which was dose dependent(P<0.01). Plasma levels of CGRP and TNF-α were not significantly different among the six groups of rats(P>0.05). Though the plasma levels of TNF-α were tended increasing along with the dose increases of selenium in the selenium supplemented rats, the differences were not significant.Conclusions Under hypoxic condition, selenium supplementation could decrease plasma levels of ANG-II and ET-1, which implies that selenium could reduce blood vessel contract and decrease blood pressure caused by hypoxia. But selenium supplementation could increase plasma TNF-α, which might be a factor of vascular endothelial cell damage. The final outcome of selenium supplementation on the effect of cardiovascular system and the potential mechanisms under the condition of hypoxia need to be further studied.