Excretion and Tissue Distribution of Radioactive Lysinoalanine, Nε-DL-(2-Amino-2-Carboxyethyl)-U-14C-L-Lysine (LAL) in Sprague-Dawley Rats

Abstract

Rats were fed either a control soybean protein diet or a diet containing 3,000 ppm soybean protein-bound lysinoalanine (LAL) for 4 or 6 weeks, at which time all rats were dosed by stomach tube with 14C-LAL labeled in the lysine moiety. Urinary and fecal excretion and tissue distribution were followed in one experiment at 6, 12, 18, 24, 48 and 72 hours. Excretion in urine, feces and expired air was followed in the other metabolic experiment at 2-hour intervals for 48 hours, and at 24-hour intervals for the next 7 days. Tissue samples were counted and LAL determination was made by amino acid analysis in both experiments. The group of rats fed LAL excreted slightly more LAL than the group fed the control diet. Very little LAL remained in the rat tissues after either experiment, and the largest remaining quantity of radioactivity was found as lysine. Quantitation of 14C-lysine in the original material and in the material from rat organs showed that the rat has some capacity for converting LAL to lysine. Less than 0.5% of the original 14C remained in any organ examined 9 days after dosing in the either control or LAL-fed rats. Autoradiographs of the kidneys 24 hours after dosing showed that the radioactive material had accumulated in the proximal convoluted tubules of the corticomedullary junction.

Dose‐dependent utilisation of casein‐linked lysinoalanine, N(epsilon)‐fructoselysine and N(epsilon)‐carboxymethyllysine in rats

“…This has also been demonstrated in rats to which N e -DL-(2-amino-2-carboxyethyl)-U-14 C-L-lysine was administered as a bolus dose [30].…”

“…In the present study, the intestinal microorganisms of adult rats which were welladapted to LAL-containing standard chow might efficiently degrade protein-linked LAL. Finot et al [29] and Struthers et al [30] both reported 14 CO 2 excretion after feeding 14 Clabelled LAL and hypothesised LAL oxidation by intestinal microorganisms. Sternberg and Kim [35] could even show that two intestinal microbiota, Escherichia coli and Bacillus subtilis, were able to utilise LAL as source of lysine, resulting in bacterial growth.…”

Urinary excretion of advanced glycation end products in dogs and cats

“…Finally, fourth, other routes of excretion may also play a role in elimination of AGEs in dogs and cats, for example faecal excretion, gut microbiota degradation or biodegradation in the body. A study of Delgado‐Andrade et al (2012) showed that dietary CML is excreted mainly by faecal excretion, a route which was also shown in the excretion of LAL (Struthers et al, 1980).…”

“…Intravenous injection of CML and CEL in rats showed temporary deposition in the liver (Bergmann et al, 2001). Ingestion of labelled‐LAL in rat demonstrated a long retention time in the kidney, since it remained in the kidney until 9 days after dosing but not found in other organs such as spleen, lung, liver and gut (Struthers, Brielmaier, Raymond, Dahlgren, & Hopkins, 1980). Finally, fourth, other routes of excretion may also play a role in elimination of AGEs in dogs and cats, for example faecal excretion, gut microbiota degradation or biodegradation in the body.…”

Urinary excretion of dietary Maillard reaction products in healthy adult female cats1,2

“…This result is supported by an earlier study by Bergmann et al (2001) using intravenous distribution of [ 18 F]fluorobenzoylated CML. When 14 C-radiolabeled LAL was dosed to rats by stomach tube, 61.7% was excreted within 72 h, of which 53.9% was found in urine, suggesting the kidney as the primary excretion route of elimination (Struthers et al, 1980).…”