FATE OF 75Se-SELENOMETHIONINE IN THE GASTROINTESTINAL TRACT OF SHEEP
A total of 30 wethers was used to study the movement of 75Se-selenomethionine in tissues and contents of various sections of the digestive tract after a single oral or intravenous dose of the selenocompound. After intravenous administration, 75Se-selenomethionine was detected in the upper part of the small intestine lumen after 3–5 h and to a lesser extent in the abomasum contents at 24 h. The highest specific activity (cpm/g of fresh tissue) in gastrointestinal tract tissue was found in the upper jejunum at 3 h postdosing. When the labeled selenocompound was given orally, the midjejunum tissue had the highest 75Se specific activity at 24 h. Supernatant and sediment fractions of gastrointestinal tract contents resulting from centrifugation at 30,000 × g were treated with 20% trichloroacetic acid. For both modes of administration, the trichloroacetic acid-soluble portion of the various gastrointestinal tract contents had higher 75Se activity in the supernatant than in the sediment. Up to 24 h, the acid-soluble part of the two centrifugal fractions was much higher for the upper part of the small intestine than for the fore-stomach contents.