|Van Goudoever, Johannes|
|Burrin, Douglas - Doug|
Submitted to: Pediatric Research
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2005
Publication Date: 5/1/2005
Citation: Riedijk, M.A., Stoll, B., Chako, S., Sunehag, A.L., Van Goudoever, J.B., Burrin, D.G. 2005. Intestinal sulfur amino acid metabolism in neonatal piglets [abstract]. Pediatric Research. 57:1608. Interpretive Summary: Interpretive Summary not needed for this 115.
Technical Abstract: BACKGROUND: Methionine (Met) is an essential sulfur amino acid that functions as a key precursor for the synthesis of homocysteine and cysteine, via transmethylation (TM) and transsulfuration (TS), respectively. Cysteine is a semi-essential amino acid in neonates.We previously showed that significant catabolism of essential amino acids, such as lysine and leucine, occurs in the gut. A significant amount of methionine seems to be converted to cysteine in the intestine of adult humans. OBJECTIVE: Our first aim was to quantify the first-pass splanchnic metabolism of dietary methionine in the gut. Secondly we wanted to quantify the metabolic fate of methionine utilized by the portal drained viscera (PDV). DESIGN/METHODS: Four-week-old, formula fed piglets (n=16) were implanted with catheters in the carotid artery, jugular vein, portal vein, duodenum and a portal flow-probe on the portal vein. Piglets were given an intravenous (IV) and intraduodenal (ID) infusion of [1-13C]methionine and [2H3]methionine on two separate days, in a cross-over design. The diet supplied a daily intake of 0.25g methionine and 0.31g cystine per kg body weight. Plasma arterial and portal methionine concentrations were measured by HPLC and isotopic enrichments of methionine, homocysteine and 13CO2 were measured by GC-(IR)MS. RESULTS: Total net methionine utilization by the PDV was 20 ± 12% of dietary methionine intake. The PDV preferentially metabolized systemic methionine rather than dietary methionine. Intestinal TM and TS represented 25 ± 7% and 18 ± 6% of whole body methionine flux, respectively. PDV homocysteine release (TM) was 12 ± 7% of PDV methionine uptake and PDV 13CO2 release (TS) was 15 ± 9% of PDV methionine uptake. CONCLUSIONS: We conclude that no first-pass metabolism of dietary methionine occurs at this intake, but that PDV metabolism of systemic arterial methionine consumes the equivalent of 20% of the dietary intake. Our results also demonstrate that the neonatal PDV tissues are capable of TM and TS of methionine. However, this represents a relative minor contribution of whole body methionine metabolism.