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Interpretive Summary: Equine enterocytes actively oxidize L-glutamine, but do not synthesize L-citrulline or L-arginine from L-glutamine or L-proline in vitro

By: Rafael E. Martinez, Jessica L. Leatherwood, Amanda N. Bradbery, Brittany L. Silvers, Jennifer Fridley, Carolyn E. Arnold, Erin A. Posey, Wenliang He, Fuller W. Bazer, and Guoyao Wu

The amino acid arginine (Arg) is a precursor for the synthesis of multiple biological molecules including nitric oxide, polyamines, and creatine that are involved in cell proliferation, cellular remodeling, dilation of blood vessels, and phosphocreatine production for a readily available source of energy. Multipurpose capabilities of Arg have increased the interest in its effects in other species and must be evaluated in the horse. Levels of Arg are deficient in the milk of mammals such as humans, cows, sheep, and pigs, but their neonates are capable of synthesizing citrulline and Arg from glutamine and proline in the small intestine. High concentrations of Arg in milk have been observed in the horse, warranting investigation in case that the foal cannot synthesize Arg to support growth and thus rely on milk as the sole source of Arg. To date, no research has determined the endogenous production of Arg in horses to support metabolic and physiological processes; therefore, our experiment quantifies the synthesis of Arg in enterocytes of the small intestine of neonatal, adult, and aged horses. Data collected from this study serve as the necessary f irst step to determine the Arg requirement in the horse that has over-reaching implications to improve the growth, performance, reproductive efficiency, and to enhance longevity of the horse.

Read the full article on the Journal of Animal Science.