A comparison of the metabolism of intravenously injected sodium selenite, sodium selenate, and selenomethionine in rats

Abstract

Rats were injected with Se 75 -sodium selenite, Se75-sodium selenate, and Se75-selenomethionine, and the distributions of Se75 in tissues, and in proteins isolated from plasma, liver supernatants, and kidney supernatants, were studied as a function of time.The livers of rats injected with selenite had a much greater initial Se75 concentration than those from rats receiving selenate. Kidneys of rats injected with selenite had a peak Se 75 concentration in the sample taken 1 hr after injection; this was followed by a rapid decline. Kidneys from rats injected with selenate had an almost constant Se75 level in all samples from 1 hr to 7 days. In other tissues the Se 75 activities for rats injected with selenite were similar to those for rats injected with selenate. As has been reported elsewhere the tissues retaining the highest Se 75 levels were the livers, kidneys, and adrenals.Rats injected with selenomethionine contained greater Se 75 concentrations in the pancreas than rats injected with selenite or selenate.Dialysis of plasma and liver and kidney supernatants against isotonic saline showed that at I hr after injection selenomethionine was associated with protein to a greater extent than was selenite or selenate. Disulphide-cleaving reagents (mercaptoethanol and cysteine) and urea were effective in releasing Se75 from liver, kidney, and plasma proteins from rats injected with either selenomethionine, selenite, or selenate. Se i ;, distribution patterns in liver. kidney, and plasma proteins separated by gel filtration or disc-electrophoresis were very similar for samples collected at I day, 3 days, and 7 days after injection of rats with either selenite, selenate, or selenomethionine. If, as has been rroposed, selenium from selenite or selenate is present in protein as selenotrisulphide, this finding suggests that selenomethionine may not be incorporated into protein intact.115

The metabolism of [75Se]selenomethionine in four women

“…Whether 7"e from [75Sc]selenomethionine or from [75Se]sclenite is incorporated into the same proteins is, as yet, uncertain. In rats, this seems most likely (Millar, Gardiner & Sheppard, 1973) but Burk (1974) found some differences between man and rats in the metabolism of [75Se]selenite. In our studies, the longer biological half-times for 75Se in plasma after giving [75Se]selenomethionine (Table 5 ) indicate a slower turnover in man of Se given in this chemical form.…”

Metabolism of selenite, selenomethionine and feed-incorporated selenium in lactating goats and dairy cows

“…In rat kidney, specific activity of 75 Se was highest one hour after injection of 75Se-labeled selenite or selenomethionine (Millar et al 1973). In the kidney selenium is rapidly incorporated into proteins and within a few hours after injection of selenite, selenate or selenomethionine most of selenium has been found in the protein fraction (Millar 1972, Millar et al 1973.…”

Baseline risk assessment of ground water contamination at the uranium mill tailings sites near Rifle, Colorado. Revision 1

“…At low intake levels, selenium is retained and accumulates in the reproductive organs, brain, and thymus, with only transient accumulation in other organs. Selenite-derived selenium accumulates in the liver and kidneys more rapidly than selenium derived from selenate (Millar et at., 1973). There is some indication that organically bound forms of selenium exist in a separate, more bioavailable pool than either selenite or selenate.…”