DEFICIENCY AND TOXICITY OF SELENIUM ALTER THE ACETYLCHOLINE STIMULATED CONTRACTION OF ISOLATED RABBIT ILEUM

It is generally maintained that combined deficiency of selenium (Se) a nd vitamin E leads to several diseases in humans as well as to the tis sue damage resulting from toxicity. The abnormalities rised from its d eficiency can be reversed by the administration of various forms of Se . However, there is a narrow margin between therapeutic and toxic dose s. The present study was designed to investigate and compare the effec ts of dietary Se and vitamin E on the contractility of ileal smooth mu scle. Young rabbits of both genders were fed with either a standardize d Se and vitamin E adequate diet, a Se and vitamin E deficient diet or a Se rich diet. Deficiency or excess of Se was verified by direct met hods (blood Se and glutathione peroxidase analyses) while the acetylch oline-induced contraction amplitude of both experimental group were me asured as depressed with respect to the control group (p < 0.05); thes e depressed amplitudes were also observed when we replaced the bath Ty rode calcium content with 2-fold calcium. Moreover, the mean amplitude of acetylcholine-induced contraction of ileum preparations in both ex perimental and control groups was in the same range when we replaced b ath solution with calcium-free Tyrode solution. Our results can demons trate the oxidative effects on smooth muscle contractility increased w ith Se deficiency or excess in diet, and its relationship with calcium . Although it has been pointed out that Se is a highly toxic agent and caution has to be taken, this can be an overriding objection against supplementation of the diet with low doses of Se.