Free Access
Reprod. Nutr. Dev.
Volume 43, Number 4, July-August 2003
Page(s) 385 - 393
Reprod. Nutr. Dev. 43 (2003) 385-393
DOI: 10.1051/rnd:2003025

Urinary selenium excretion in selenite-loaded sheep and subsequent Se dynamics in blood constituents

Klaudia Boldi Árováa, L'ubomíra Gresákováa, Stefan Faixa, Mikulás Levkutb and L'ubomír Lenga

a  Institute of Animal Physiology, Slovak Academy of Sciences, Soltésovej 4, 040 01 Kosice, Slovak Republic
b  Institute of Pathological Anatomy, University of Veterinary Medicine, Komenského 73, 041 81 Kosice, Slovak Republic

(Received 17 March 2003; accepted 25 June 2003)

Renal selenium excretion in sheep was measured during intravenous infusion of sodium selenite, and the post-infusion dynamics of Se levels in whole blood, plasma and red blood cells (RBC) were investigated for the next 5 days. The plasma Se level increased almost twenty fold with the infusion of Na 2SeO 3 (from $0.39 \pm 0.02$ to $7.83 \pm 0.33~\mu$mol $\cdot$L -1, P < 0.001) compared with the baseline value. The selenium concentration in urine ( $0.07 \pm 0.02$ vs. $18.53 \pm 2.56~\mu$mol $\cdot$L -1, P < 0.001), the amount of Se excreted ( $0.14 \pm 0.07$ vs. $21.40 \pm 2.31$ nmol $\cdot$min -1, P < 0.001) and the renal clearance of Se ( $0.19 \pm 0.03$ vs. $3.01 \pm 0.34$ mL $\cdot$min -1, P < 0.001) were found to be highly significantly elevated during selenite loading. The clearance measurements showed no changes in the urinary flow rate or in the glomerular filtration rate. During and at the end of infusion the highest Se level was attained in plasma, followed by whole blood and RBC. The plasma Se level fell rapidly within 10 min after the end of infusion, but the concentration of Se in RBC was stable up to the fourth hour, when it started to decrease too. On day 5 the Se concentrations in plasma, RBC and whole blood were found to be only slightly but still significantly higher than before the selenite infusion. The large disproportion between the infusion rate of Se (8.76  $\mu$g $\cdot$min -1) and its renal excretion rate (1.69  $\mu$g $\cdot$min -1) found in clearance measurements suggests low glomerular filtration of infused selenium, which might primarily be caused by the binding of selenite metabolites to blood constituents. The presented results confirm the low bioavailability to ruminants of Se from sodium selenite.

Key words: sheep / sodium selenite / renal function / selenium excretion

Correspondence and reprints: Klaudia Boldi Árová

© INRA, EDP Sciences 2003