Tissue and concentration-dependent effects of sodium selenite on muscle contraction |
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Authors: | B Turan E Koç Ö Hotomaroglu E Kiziltan S Yildirim E Demirel |
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Institution: | (1) Department of Biophysics, Faculty of Medicine, University of Ankara, Ankara, Turkey;(2) Department of Physiology, Faculty of Medicine, University of Ankara, Ankara, Turkey;(3) Department of Pharmacology, Faculty of Medicine, University of Ankara, Ankara, Turkey |
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Abstract: | In this study, we demonstrated that sodium selenite with high doses (≥ 10-3 M) were potent in inducing a contracture type effect on heart and smooth muscles. Selenite (Se), at a concentration of 10-3
M, caused a contracture effect in heart preparations. Also, low Se concentrations did not have any significant effect. Although
low concentrations of Se (≥ 10-5 M) had a biphasic effects on acetylcholine (ACh) induced and spontaneous ileum contractions, 10-3
M selenite enhanced once more a contracture effect similar to that of the heart preparations. Replacing Ca2+ concentration of the bathing solution by twofold Ca2+ or Ca2+-free did not change the effects of selenite (10-5
M) on contractility of ileum preparations. In vascular smooth muscle, low concentration of selenite (<10-4) had no significant effects on KC1, and phenylephrine-induced contractions and acethylcholineinduced endothelium-dependent
relaxations of isolated rabbit aorta. However, the contractions induced by phenylephrine and the relaxations induced by acetylcholine
in rabbit aorta were depressed significantly by high concentration of selenite (10-3
M). The results obtained by selenite exposure from these three different types of tissue preparations first suggest that the
high concentration of selenite exposure induces some alterations in the functions of muscles and endothelium in a tissue and
dose-dependent manner. Second, this observed irreversible type of dysfunction of tissues induced by l0-3
M selenite is not directly dependent on the Ca2+ entrance into the cytosol, but might be induced by the increase of intracellular Ca2+ with the disturbance of Ca2+ regulation. |
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Keywords: | Sodium selenite heart atrium aorta phenylephrine ileum contractility |
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