{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,12]],"date-time":"2026-01-12T21:24:26Z","timestamp":1768253066834,"version":"3.49.0"},"reference-count":36,"publisher":"Oxford University Press (OUP)","issue":"4","license":[{"start":{"date-parts":[[2022,3,11]],"date-time":"2022-03-11T00:00:00Z","timestamp":1646956800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/journals\/pages\/open_access\/funder_policies\/chorus\/standard_publication_model"}],"funder":[{"DOI":"10.13039\/100014840","name":"American Quarter Horse Foundation","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100014840","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2022,4,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:p>In livestock species, the enterocytes of the small intestine are responsible for the synthesis of citrulline and arginine from glutamine and proline. At present, little is known about de novo synthesis of citrulline and arginine in horses. To test the hypothesis that horses of different age groups can utilize glutamine and proline for the de novo synthesis of citrulline and arginine, jejunal enterocytes from 19 horses of three different age groups: neonates (n = 4; 7.54 \u00b1 2.36 d of age), adults (n = 9; 6.4 \u00b1 0.35 yr), and aged (n = 6; 22.9 \u00b1 1.0 yr) with healthy gastrointestinal tracts were used in the present study. Enterocytes were isolated from the jejunum and incubated at 37 \u00b0C for 30 min in oxygenated (95% O2\/5% CO2) Krebs bicarbonate buffer (pH 7.4) containing 5 mM D-glucose and 0 mM, 2-mM L-[U-14C]glutamine, or 2 mM L-[U-14C]proline plus 2 mM L-glutamine. Concentrations of arginine, citrulline, and ornithine in cells plus medium were determined using high-performance liquid chromatography. Results indicate that the rate of oxidation of glutamine to CO2 was high in enterocytes from neonatal horses, but low in cells from adult and aged horses. Enterocytes from all age groups of horses did not degrade proline into CO2. Regardless of age, equine enterocytes formed ornithine from glutamine and proline, but failed to convert ornithine into citrulline and arginine. Because arginine is an essential substrate for the synthesis of not only proteins, but also nitrogenous metabolites (e.g., nitric oxide, polyamines, and creatine), our novel findings have important implications for the nutrition, performance, and health of horses.<\/jats:p>","DOI":"10.1093\/jas\/skac077","type":"journal-article","created":{"date-parts":[[2022,3,11]],"date-time":"2022-03-11T17:20:28Z","timestamp":1647019228000},"source":"Crossref","is-referenced-by-count":2,"title":["Equine enterocytes actively oxidize <scp>l<\/scp>-glutamine, but do not synthesize <scp>l<\/scp>-citrulline or <scp>l<\/scp>-arginine from <scp>l<\/scp>-glutamine or <scp>l<\/scp>-proline in vitro"],"prefix":"10.1093","volume":"100","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3873-8230","authenticated-orcid":false,"given":"Rafael E","family":"Martinez","sequence":"first","affiliation":[{"name":"Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jessica L","family":"Leatherwood","sequence":"additional","affiliation":[{"name":"Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research, College Station, TX 77843, USA"},{"name":"Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Amanda N","family":"Bradbery","sequence":"additional","affiliation":[{"name":"Department of Animal and Range Sciences, Montana State University, Bozeman, MT 59717, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2265-3857","authenticated-orcid":false,"given":"Brittany L","family":"Silvers","sequence":"additional","affiliation":[{"name":"Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jennifer","family":"Fridley","sequence":"additional","affiliation":[{"name":"Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Carolyn E","family":"Arnold","sequence":"additional","affiliation":[{"name":"Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Erin A","family":"Posey","sequence":"additional","affiliation":[{"name":"Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wenliang","family":"He","sequence":"additional","affiliation":[{"name":"Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fuller W","family":"Bazer","sequence":"additional","affiliation":[{"name":"Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guoyao","family":"Wu","sequence":"additional","affiliation":[{"name":"Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research, College Station, TX 77843, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"286","published-online":{"date-parts":[[2022,3,11]]},"reference":[{"key":"2022042011131598100_CIT0001","doi-asserted-by":"crossref","first-page":"474","DOI":"10.1186\/2193-1801-3-474","article-title":"Rapid publication-ready MS-Word tables for one-way ANOVA","volume":"3","author":"Assaad","year":"2014","journal-title":"SpringerPlus"},{"key":"2022042011131598100_CIT0002","doi-asserted-by":"crossref","first-page":"772","DOI":"10.1111\/rda.13422","article-title":"Effects of dietary l-arginine supplementation to early pregnant mares on conceptus diameter-preliminary findings","volume":"54","author":"Aurich","year":"2019","journal-title":"Reprod. 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